Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
438 AM AST Wed Mar 20 2024


.SYNOPSIS...
Issued at 435 AM AST Wed Mar 20 2024

Today and tomorrow, a pre-frontal trough will lead to an uptick in
shower activity across the area. Slow steering winds will contribute
to increased rainfall accumulations. As a result, a limited to
elevated flooding threat can be expected, particularly over interior
Puerto Rico. Looking ahead, a strong low-pressure system and
associated frontal boundary are forecast to impact the local islands
by early next week. However, uncertainty persists regarding the
timing, location, and eventual rainfall amounts associated with
these features.

&&

.SHORT TERM...Today through Friday...

Clear skies prevailed across Puerto Rico under a very light wind
flow. The current satellite-derived precipitable water imagery show
a dry air mass engulfing the local islands, with a moisture
gradient over the local Atlantic waters. This moisture is associated
to a cold front now over the Bahamas and Cuba, and a prefrontal
trough near eastern Hispaniola. As the day progresses, the moisture
field will approach the area, with precipitable water values
climbing to near normal values for this time of year. The low
pressure associated with the cold front will maintain the gradient
loose, hence winds will remain on the light side. In fact, the low
level steering flow is expected to be around 2 to 8 knots today.
Since skies are clear, enough sunshine is expected to warm up the
surface, with local effects kicking in, resulting in shower activity
developing over the Cordillera Central in Puerto Rico. Due to the
light winds, these showers are not expected to move much, but should
drift mostly toward the south and west. Some minor flooding cannot
be ruled out.

As the workweek ends, a ridge building over the western Atlantic
will cause the winds to shift from the northeast, and strengthen
some. On Thursday, the low level steering flow will be from the
northeast at around 8-10 knots, increasing to nearly 15 knots by
Friday. This ridge will push more moisture from the front into the
local islands. A shortwave trough is also expected to cross the
region on Thursday, so conditions aloft will allow for better
dynamics for shower generation. Regardless, on both days, showers
are expected to develop over the interior, moving toward the south
and west of Puerto Rico. The chances of rain are better on Thursday,
as some patches of drier air are expected to move over the area on
Friday, limiting the coverage of the rainfall activity.

In terms of temperatures, 925 mb values are still above normal for
today, although not as high as yesterday. Still some urban areas
along northern Puerto Rico could experience values above 102 degrees
Fahrenheit. Heat indices should be at 90-95F over the Virgin
Islands. Temperatures should cool down a little for Thursday and
Friday, but with highs still reaching the mid and upper 80s.

&&

.LONG TERM...Saturday through Wednesday...

Moisture availability from the remnants of a frontal boundary will
continue to stream across the region this weekend. Moisture levels
will be near to above climatological normals. The pressure gradient
will tighten as a strong low-pressure system exits the Eastern
Seaboard and pushes against a surface high pressure over the
northern Atlantic. This will promote breezy wind conditions from the
east-southeast. Shower activity will be mostly shallow during this
period, moving quickly due to fast-steering winds. This could
somewhat inhibit rainfall accumulations across the islands.
Nevertheless, ponding of water on roadways and in poor drainage
areas is possible.

Model guidance continues to suggest a frontal boundary approaching
the region from the northwest by late Sunday into early next week.
This front is associated with the aforementioned strong low-pressure
system. Although models have been consistent in the development of
these features, timing, and position continue to differ, not only
between models but also between each model cycle. The 20/00z GFS
model shows the upper-level features a little bit east and north of
the local islands compared to previous runs. However, the surface
low meanders over Puerto Rico and the U.S. Virgin Islands. The
20/00Z ECMWF now places these features a bit closer than before,
with both models indicating the low closest to the islands by
Wednesday. The limiting factor will be moisture availability. Models
suggest a frontal passage (FROPA) by late Tuesday. After the frontal
passage, moisture levels are expected to plummet from approximately
1.60 inches to less than 1.0 inches.

As such, uncertainty persists regarding when the frontal boundary
will be nearest, whether it will pass over the islands, and the
amount of moisture it will bring into the area. This uncertainty
arises from both the front itself and potential moisture convergence
over the area ahead/southeast of the front as it interacts with the
deep-layered low-pressure system.

In summary, stability is expected to decrease from late this weekend
into midweek of next week as the deep-layered trough and associated
frontal boundary approach from the northwest. Moisture convergence
over the region is likely to occur early next week, with the most
probable timing being late Monday into Tuesday. By Tuesday, the
frontal boundary is forecast to be near or over the islands, further
enhancing shower and thunderstorm activity. However, the full
impacts of this frontal boundary remain unclear. Shifting and slow
steering winds will influence the location of the strongest shower
activity, with the extent of wind shifts largely depending on
whether or not a frontal passage occurs. At most, a limited to
elevated flooding threat can be expected, with urban and small
stream flooding likely, and isolated flash flooding in some areas.
Landslides in the most vulnerable places cannot be ruled out.


&&

.AVIATION...
(06Z TAFS)
Issued at 435 AM AST Wed Mar 20 2024

Mainly VFR conditions expected to prevail. SHRA are expected to
develop after 17Z across the Cordillera Central, spreading toward
the south and west. This activity could reach TJPS from 17-22z,
with reduced VIS and low ceilings possible. Winds are on the light
side, out of the ENE at 10 knots or less.

&&

.MARINE...
Issued at 435 AM AST Wed Mar 20 2024

Light east to southeast winds will continue today as the surface
high pressure builds over the eastern Atlantic and a cold front
approaches the northeast Caribbean from the western Atlantic. The
cold front will induce a pre-frontal trough off to the northwest of
PR today. The frontal boundary will linger north of the region
through the second part of the work week, while the moderate to
locally fresh trade winds will push fragments of moisture over the
local waters. Another surface high pressure will build over the
western Atlantic, increasing the winds and seas during the weekend.

&&

.BEACH FORECAST...
Issued at 435 AM AST Wed Mar 20 2024

Today, winds will be calmer, resulting in a low rip current risk
across all beaches of the local islands. However, winds are expected
to increase by the end of the workweek, raising the rip current risk
to moderate once again, mostly across the northern exposed beaches
of the islands.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
355 AM AST Thu Mar 21 2024


.SYNOPSIS...
Showers are expected to develop this afternoon under a light wind
flow. This activity is expected to be focused over the interior
and southern Puerto Rico. Temperatures will be on the warm side
this weekend, with heat indices above 102 degrees possible. Then,
a frontal system is expected to bring showers and possibly
thunderstorms by late Sunday into early in the weekend. Tranquil
weather is expected Wednesday onward, but with deteriorating
marine conditions.

&&

.SHORT TERM...Today through Saturday...

A stationary front located north of Puerto Rico triggered strong
convective activity over the Atlantic waters. Satellite imagery
depicted robust outflows from this convective activity, which moved
southward toward northern Puerto Rico earlier in the night. As these
outflows interacted with the land breeze, a line of showers formed
just off the coast of San Juan. However, the line dissipated fairly
quickly, leaving only isolated showers over the area during the
night hours. Rainfall amounts between a tenth to half an inch were
recorded in isolated areas of the San Juan metropolitan coastal
area. Some activity persists over the northwestern portions of the
Atlantic waters due to this frontal system. However, for the
remainder of the morning hours, not much precipitation can be
expected, with only a few showers occurring here and there.

Satellite-derived precipitable water data indicates PWAT values in
the range of 1.6 to 1.7 inches, which exceed the 90th percentile of
the climatological normal, suggesting above-normal levels. This
moisture level is expected to persist through at least Friday as the
frontal boundary stalls just north of the region. Moisture levels
will slightly diminish to 1.5 inches on Saturday but are still
expected to remain mostly above the 75th percentile of the
climatological normal.

In terms of dynamics, the proximity of the frontal boundary will
promote some low-level instability, with 850-700 mb lapse rates
expected to remain above normal today and decrease slightly
tomorrow. However, stability at the mid- to upper levels is
anticipated to be slightly greater compared to previous days as a
weak ridge develops in the next few days. The 500 mb temperatures
are forecast to increase slightly to -5 and -4 degrees Celsius today
and tomorrow. Consequently, the 700-500 mb lapse rates are expected
to remain mostly below normal levels. This will somewhat hinder
thunderstorm activity across the area. Although thunderstorms were
not included in the forecast as most of the activity appears to be
shallow, one or two short-lived thunderstorms may still occur over
the Atlantic waters and in mountainous areas of Puerto Rico, mostly
this afternoon.

Rainfall accumulations, on the other hand, may be enhanced today due
to light northeastern steering winds promoting slow-moving showers.
Model guidance suggests shower activity initiating over the
Cordillera Central after 18z today and slowly drifting southward,
affecting Ponce and adjacent municipalities through at least 23z.
Because of the potential prolonged duration of these showers, a
limited to elevated flooding threat is possible. Therefore, urban
and small-stream flooding can be expected, with isolated flash
flooding not being ruled out.

The pressure gradient over the local area will tighten as a strong
low-pressure system exiting the Eastern Seaboard pushes against a
surface high-pressure system over the northern Atlantic.
Consequently, winds will shift more easterly and speeds will
increase through Saturday. Although moisture levels are not expected
to fluctuate much for the rest of the forecast period, faster
steering winds will reduce rainfall accumulations during afternoon
convective activity. Therefore, the weather pattern will become
breezy with a limited threat of flooding, if any, in the presence of
shower activity across the area.

&&

.LONG TERM...Sunday through Thursday...

As a cold front approaches from the west, winds from the surface
up to 750 mb are expected to shift from the southeast. This will
result in very warm or hot temperatures across the region, with
heat indices likely above 102 degrees for many areas in northern
and western Puerto Rico, and above 90 degrees elsewhere in low-
elevated areas. Moisture associated with the front will increase
on Sunday night and early in the workweek, with values above
normal for this time of year. As the frontal system approaches,
instability will also increase, thus widespread showers and
isolated thunderstorms are anticipated. The risk for urban and
small stream flooding will be elevated. It is worth mentioning
that, even with some difference in timing and coverage, the global
models agree in the generally wet pattern for early next week.

After the frontal system moves, the winds will shift from the
northwest, bringing a cooler and drier air mass across the
islands. Conditions will begin to dry out on Tuesday, although
with some lingering showers, and even additional shower
development over southeastern Puerto Rico and near Saint Croix.
It should be enjoyable on Wednesday and Thursday, with lot of
sunshine and temperatures in the low 80s in the afternoon hours.
Regardless, small and shallow pocket of moisture may still linger
around, so a few showers cannot be ruled out during this period.


&&

.AVIATION...
(06Z TAFS)

Mainly VFR conditions expected across most terminals. Winds will
remain lgt and vrbl til 21/13z, then increase up to 12 kt and shift
more ENE aft 21/14z, with sea breeze variations. Mtn obs psbl aft
21/18z with MVFR for TJPS through 21/22z as SHRA moves towards the
terminal. PROB30 group added for TJPS as brief IFR/LIFR cannot be
ruled out during this period.

&&

.MARINE...
Light easterly winds will continue as a cold front lingers north of
the area today. A surface high pressure building over the western
Atlantic will yield moderate to locally fresh east- northeast winds
starting Thursday night, and thus, causing deteriorating marine
conditions during the weekend. These winds will push fragments of
moisture over the local waters.


&&

.BEACH FORECAST...
The rip current risk is currently moderate for north-central
Puerto Rico, but all north-facing beaches in Puerto Rico and the
U.S. Virgin Islands will see this risk increase by tonight and
stretching into the weekend. Breaking waves should be around 5
feet in this areas. The risk will remain low for the beaches
in the Caribbean Sea.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
440 AM AST Fri Mar 22 2024


.SYNOPSIS...
Showers are expected to develop this afternoon across the interior
and southwestern Puerto Rico, where an elevated risk of flooding
exist. The weekend will be hot and breezy, but a cold front will
bring wetter conditions on Monday and Tuesday, with cooler
temperatures and drier conditions after that. A northerly swell is
expected to arrive on Tuesday, deteriorating marine and beach
conditions

&&

.SHORT TERM...Today through Sunday...

Fairly calm conditions prevailed during the night, with only a few
very isolated showers observed across windward coastal areas. A
similar weather pattern is anticipated for the remainder of the
morning.

Today, a surface high-pressure system north of the Atlantic will
gradually shift eastward, inducing more east-northeast winds across
the region. Concurrently, a robust low-pressure system forming over
the Carolinas will slowly progress eastward, moving towards the
Atlantic waters and exerting pressure against the aforementioned
high-pressure system. This interaction will result in a tightening
pressure gradient over the northern Caribbean, thereby increasing
wind speeds as well. Moisture levels at low to mid-levels will
remain above normal throughout the day, as remnants of a frontal
boundary continue to enhance moisture convergence over the local
area. Marginal instability will persist, with 700-500 mb lapse rates
gradually increasing to normal levels as the day progresses.
Consequently, we can anticipate a similar afternoon to yesterday,
with showers and very isolated thunderstorms developing as diurnal
heating combines with marginal instability across Puerto Rico.

The notable difference today will be the distribution of
precipitation, as east-northeast winds will drive showers primarily
over the interior and southwestern regions of Puerto Rico.
Additionally, due to faster steering winds, showers will move more
swiftly than in previous days. Nonetheless, areas affected by these
showers and thunderstorms should remain vigilant, as urban and small-
stream flooding could still occur.

For the remainder of the short-term forecast, the potent deep-
layered low-pressure system and its associated frontal boundary will
gradually approach our forecast area. While recent model cycles
indicate a slightly more northerly track for the low, our weather
conditions will still be closely tied to the evolution of these
features. Winds are anticipated to shift more towards the east-
southeast by Saturday and then become southerly by Sunday. At the
925 mb level, temperatures are forecast to surge above the 99th
percentile, significantly surpassing the climatological normals for
this time of year. This could potentially result in record-breaking
temperatures if cloud coverage doesn't disrupt the diurnal heating
pattern.

Moisture levels are forecast to remain above normal on Saturday and
near normal on Sunday, with dynamics expected to be marginal and
possibly increasing by Sunday. On Saturday, anticipate some
afternoon showers, primarily over interior and northwestern Puerto
Rico. However, Sunday's weather conditions will heavily depend on
the track of the low-pressure system. According to model guidance,
shower and thunderstorm activity on Sunday is likely to be clustered
over the Atlantic waters. With a southerly flow in place, it appears
that the northern half of Puerto Rico and the northern US Virgin
Islands will be most affected. Nevertheless, there is a possibility
that the majority of the activity will remain over the waters.
Regardless, anticipate shower and possible thunderstorm activity
affecting northern Puerto Rico in the afternoon, possibly shifting
to windward coastal areas of the islands during the evening hours.
Stay tuned as this event unfolds, possibly impacting the local
islands through early next week.

&&

.LONG TERM...Monday through Friday...

The workweek should begin on a wet note, as a cold front
approaches the local islands from the west. The system appears to
preserve definitions all the way up into the mid-levels of the
atmosphere, so conditions should be favorable for periods of heavy
rain and isolated thunderstorms on Monday and Tuesday. First, on
Monday, the areas that should begin to receive the greatest
amounts of rain will be the north and west of Puerto Rico, but
the moisture field will eventually move into the southern half of
Puerto Rico, reaching the Virgin Islands late Monday or early
Tuesday. The global models agree on this frontal passage early in
the week, although the ECMWF is a little faster, ending most of
the rain by late Monday.

Moving into the middle of the week, columnar moisture decreases,
with precipitable water values likely dropping below 1.0 inch, and
a trade wind cap inversion developing around 850 mb. Therefore,
the potential for showers will decrease considerably, and will be
limited to small patches occasionally reaching the islands. The
wind flow will remain from the northwest for most of the week, and
fairly light. Temperatures will be a little cooler too during this
period, but with highs still reaching the mid-80s.



&&

.AVIATION...
(06Z TAFS)

Mainly VFR conditions expected across the local terminals. Winds
will continue from the E below 10 kts through 22/13z, increasing to
up to 15 kts and shifting more ENE aft 22/14z, with higher gusts and
sea breeze variations. Passing SHRA could affect TJSJ/TISX/TIST
after 23/00z, resulting in VCSH.

&&

.MARINE...
A surface high pressure building over the western Atlantic will
yield moderate to locally fresh easterly winds, causing
marine conditions to deteriorate during the weekend. These winds
will push fragments of moisture from a frontal boundary north of the
islands into the local waters. Marine conditions are expected to
deteriorate further on Tuesday as a long-period northerly swell
arrives.

&&

.BEACH FORECAST...
Breezy conditions are expected in the beach areas, especially in
the afternoon hours. The risk of rip currents is now moderate for
the north-facing beaches in Puerto Rico and the U.S. Virgin
Islands.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
342 AM AST Sat Mar 23 2024

.SYNOPSIS...

Hot and breezy conditions are expected today across much of the
region. Afternoon convection is possible across portions of
western Puerto Rico, with limited rainfall accumulations. A cold
front is forecast to approach the local area by the beginning of
the workweek, enhancing the potential for showers through Tuesday.
A northerly swell is expected to arrive by early next week,
deteriorating marine and coastal conditions until the end of the
week.


&&

.SHORT TERM...Today through Monday...

Lines of showers were observed during the night hours across the
local islands. These showers stayed mostly over the open waters,
although some accumulations were registered over southeastern Puerto
Rico. The most recent satellite imagery also shows an area of
enhanced moisture associated with an old frontal boundary that is
stationary north of the islands.

The low pressure system that is currently affecting Florida, in the
United States will eventually move into the western Atlantic, while
a surface high pressure moves eastward into the eastern Atlantic.
These system will maintain the pressure gradient tight today and
Sunday, with speeds at 15 to 25 mph. As the low pressure approaches,
the winds will shift from the southeast today, and from the south on
Sunday and Monday. Temperatures at 925 mb will increase as well,
with above normal values today, and even higher on Sunday.
Therefore, hot conditions will prevail, with heat indices above 102
degrees in coastal and urban areas, especially in north and west of
Puerto Rico. The users are urged to stay hydrated and to take breaks
often from the strong heat and sunshine.

In terms of rains, some showers may reach the islands from the
Caribbean waters, while additional activity could develop across
northwestern Puerto Rico. Since the winds are enhanced,
accumulations are not expected to be significant, and afternoon
convection should move quickly over the Atlantic waters.

On Monday, a cold front associated with the aforementioned low
pressure system will reach the islands. Conditions should be
favorable enough (although not impressive) for periods of strong
showers and isolated thunderstorms. The risk for urban and small
stream flooding will be elevated, early in the day for Puerto Rico,
and in the evening for the U.S. Virgin Islands. There is some
uncertainty in the timing of the rain activity, but in general, the
global models agree in this feature crossing the area of
responsibility.

Finally, temperatures on Monday are a little tricky. The environment
will remain favorable for hot conditions, but if cloudiness arrives
early in the day, then maximum temperatures will stay milder.


&&

.LONG TERM...Tuesday through Saturday...

Moisture associated to a passing cold front will promote wet
conditions across the islands on Tuesday until early Wednesday.
Periods of moderate to locally heavy rain are expected mainly across
southeastern Puerto Rico and the U.S. Virgin Islands during the
afternoon hours. As the cold front moves away from the local area, a
drier and stable airmass will filter into the region. This will
promote mainly fair weather conditions with limited shower activity
through at least the end of the workweek. The Precipitable Water
content Analysis (PWAT) suggest a drop of precipitable water values
between 0.60 to 0.85 inches. Therefore, no significant precipitation
is expected throughout much of the period. The wind flow will
prevail from the northwest for the most part of the workweek. By the
end of the long-term period a weak cold front is forecast to
approach the islands from the northwest, increasing the potential
for showers. However, significant accumulations are not expected
with the frontal passage. Overall, daytime temperatures will be
cooler in during the long-term period due to the prevailing
northwest winds. Nonetheless, high temperatures will reach the
mid- 80s along the coastal and urban portions of the islands with
heat indices reaching the low to mid 90s.

&&

.AVIATION...
(06Z TAFS)

Mainly VFR conditions expected to prevail through the forecast
period. SHRA will be moving across the local waters, approaching the
terminals at times, but impact to operations are expected to be
limited. However, after 17Z, stronger SHRA should develop near TJBQ,
with periods of reduced VIS and low ceilings. Winds will be shifting
from the ESE at 15-18 kts, and stronger gusts.

&&

.MARINE...

A surface high pressure building over the Western Atlantic will
promote moderate to locally fresh easterly winds. As this system
spreads into the central Atlantic and a surface low pressure and
associated frontal boundary approaches the region from the northwest,
winds will weaken and become more southerly by Sunday into early
next week. A long-dominant dominant period northerly swell will
arrive by Tuesday, promoting hazardous seas through at least
Thursday.

&&

.BEACH FORECAST...

Breezy conditions are expected in the beach areas, promoting a
moderate risk of life-threatening rip currents from the northwest
to northeastern beaches of Puerto Rico, Culebra, Vieques and the
U.S. Virgin Islands.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
355 AM AST Sun Mar 24 2024

.SYNOPSIS...

A cold front is forecast to approach the local islands by the
beginning of the workweek, with an increased potential of periods
of strong showers. Therefore, urban and small stream flooding are
possible across the region. A northerly swell is forecast to
arrive by early this week, and gradually deteriorating marine and
coastal conditions. Warm temperatures are expected today with heat
indices reaching the low 100s mainly across northern and western
Puerto Rico.

&&

.SHORT TERM...Today through Tuesday...

High clouds were observed in satellite imagery during the night
hours. Some light and isolated showers were observed as well, mainly
affecting southeastern and the eastern interior regions of Puerto
Rico, but accumulations were minimal.

The main story in the short-term period of the forecast is twofold.
A strong low pressure now east of The Carolinas and Georgia will
continue to move toward the northeast. While the center of this
system will not impact the islands, the associated cold front will.
The interaction between the low pressure and a surface high pressure
over the Central Atlantic maintains the gradient tight and the wind
flow from the southeast at around 15 knots today. These winds will
begin to shift more from the south today, and from the southwest
this evening. As the frontal system approaches, the gradient will
relax, resulting in lighter winds.

The first story for today: the southerly wind flow will stretch into
the mid-levels of the atmosphere, and temperatures at 925 mb will be
well above average. Therefore, it will be hot today, with highs in
the 90s and heat indices above 102 degrees, mainly for northern and
western Puerto Rico. In terms of rains, a few showers will reach
southern Puerto Rico and the Virgin Islands during the day, while
additional activity may develop over northwestern Puerto Rico this
afternoon. These rains are not expected to be too strong.

The second story will unfold mostly on Monday, and it's related to
the rain associated with the cold front. The global and high
resolution guidance indicate that this feature should begin to cross
the islands very late on Sunday or early Monday, with an increased
likelihood of periods of strong showers. The Galvez-Davison Index
also indicate the potential for isolated thunderstorms, as this
feature moves through. So far, accumulations should be moderate to
locally heavy, with an elevated risk of urban and small stream
flooding across Puerto Rico, and a limited risk for the Virgin
Islands.

Lastly, on Tuesday, conditions will gradually improve as dry air
filters in from the northwest. The circulation of the low pressure
will also maintain the winds from the northwest at 10 mph or less.
With this drier conditions, temperatures will not be as hot, but
with highs still in the low and mid-80s at urban and low-elevated
areas.

&&

.LONG TERM...Wednesday through Sunday...

After the frontal passage, a surface high pressure expanding from
the western to central Atlantic will dominate the local weather for
the first half of the long-term period. A drier and stable airmass
is forecast to filter into the local region, limiting the potential
for showers. The latest Precipitable Water content Analysis (PWAT)
suggest precipitable water values between 0.52 to 0.75 inches.
Therefore, fair weather conditions with no significant showers are
anticipated until late Friday into Saturday morning. The winds are
expected to steer from the northwest for much of the period in
response to the surface high pressure.

By early Saturday, a weak cold front is forecast to approach the
region from the northwest. The latest model guidance suggest an
increase in moisture across the region from Saturday into Sunday.
However, this cold front is expected to move relatively quick across
the region. Therefore, significant accumulations are not expected
with the frontal passage. By Sunday afternoon, weather conditions
will become fair and dry. A surface high pressure will establish
across the central Atlantic promoting northeast winds across the
local islands. With the frontal passages, daytime temperatures are
expected to remain in the mid 80s along the coastal and urban
areas of Puerto Rico and the U.S. Virgin Islands, and in the low
80s across the higher elevations. Heat indices will stay in the
low 90s across these sectors.

&&

.AVIATION...
(06Z TAFS)

Mainly VFR conditions expected to prevail through the
forecast period. Passing SHRA expected across the forecast area, but
with little to no impact to operations. Winds at FL050 will be from
the SE at 14-18 kts, shifting from the south around 18Z at 15 knots,
and then southwest in the evening while becoming lighter.

&&

.MARINE...

A surface high pressure over the western central Atlantic will
continue to move towards the east into the central Atlantic and
promoting moderate to locally fresh east to southeast winds across
the regional waters. A surface low pressure and associated frontal
boundary will approach the region from the northwest, as the high
pressure ridge spreads into the central Atlantic. Winds will then
become light and more southerly by late Sunday and into early next
week. A long dominant Dominant period northerly swell will arrive
late Tuesday, promoting hazardous seas through at least Thursday.

&&

.BEACH FORECAST...

Breezy conditions will continue today along the local beaches
promoting a moderate risk of life-threatening rip currents from
the northwest to northeastern beaches of Puerto Rico, Culebra and
the U.S. Virgin Islands. The risk will become high on Tuesday due
to the arrival of the northerly swells.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
500 AM AST Mon Mar 25 2024

...New SYNOPSIS, AVIATION, MARINE, BEACH FORECAST...

.SYNOPSIS...
Issued at 429 AM AST Mon Mar 25 2024

An active cold front will pass through the forecast area today
bringing showers and isolated to scattered thunderstorms. Drier
air will follow Tuesday and Wednesday. A second front will bring
some increase of showers on Saturday. Temperatures will cool today
through Wednesday and then gradually recover through the next
weekend.

&&

.SHORT TERM...SHORT TERM...Today through Wednesday...

Light and isolated showers were observed during the overnight hours
across the local islands. These showers were seen mainly over the
Caribbean waters. However, some of these showers reached the
southern and southeastern portions of Puerto Rico, leaving minor
accumulations. Light winds from the south southeast prevailed for
most of the night. Overnight temperatures stayed in the upper 70s to
low 80s across the coastal and urban portions of the islands, and in
the upper 60s to low 70s across the higher elevations.

A strong low pressure located between the east coast of the United
States and northwestern Bermuda will continue to move towards the
northeast. The associated cold front is forecast to approach the
local area from the northwest today, increasing the potential for
showers and thunderstorms. As the front crosses the islands,
periods of moderate to locally heavy showers are anticipated.
Therefore, there is an elevated risk for urban and small stream
flooding across the area. The latest model guidance suggest the
heaviest activity during the afternoon hours, mainly across the
northern half of Puerto Rico and the northern U.S. Virgin Islands.
At this moment, rainfall accumulations between 1.0 to 2.0 inches
are likely across these sectors.

Unstable weather conditions will continue until at least Tuesday
afternoon. Then, a gradual improvement is expected as the front
moves further southeast and out of the region and a drier airmass
filters into the islands. By Wednesday, dry and stable conditions
are anticipated with limited precipitation. The latest
Precipitable Water content Analysis (PWAT) suggests values of
0.50 to 0.80 inches, meaning this dry and stable
pattern will last until the end of the workweek. Winds will
prevail from the northwest at 5 to 10 mph. Despite the dry
conditions and northwest winds, daytime temperatures will remain
in the mid-80s across the region. Heat indices will reach the low
90s along the coastal areas.

&&

.LONG TERM...Thursday through Sunday...

The low pressure that brought the front today will actually move
southeast until it crosses 60 north Wednesday night. The resulting
north northwesterly flow will bring cooler and drier air into the
area, Tuesday and Wednesday. This airmass will be in place at the
beginning of the long term period, Thursday and Friday. Another
cold front will move into the area, to produce some showers and
possible a thunderstorm Saturday, but the airmass will only be
slightly cooler and will carry a little more moisture than the
airmass behind the cold front about to push through the area.
Nevertheless this will still limit shower activity throughout the
period.

High pressure at upper levels over the south central Caribbean on
Wednesday will lose most of its strength due a cut-off low that
formed on Monday east of North Carolina and drifted east on
Tuesday and southeast on Wednesday. By Thursday it will be about
820 miles northeast of San Juan, Puerto Rico forcing the ridge
into submission. The flattened ridge will pass through the
forecast area on Friday. Another trough at upper levels will not
pass through the area until Monday night.

&&

.AVIATION...
(06Z TAFS)

An approaching cold front and upper level trough are expected to
move across the regional waters and the local islands today. An
increase in TSRA/SHRA due to a FROPA may cause MVFR cigs across
the local terminals aft 25/14z. Afternoon TSRA/SHRA development
will result in VCTS/VCSH for TJSJ/TJBQ/TIST/TISX between
25/17-23Z. Winds will prevail from the SSW with higher gusts near
TSRA aft 25/14z. Maximum winds WSW-W 70-80 kts btwn FL360-460.

&&

.MARINE...
Issued at 429 AM AST Mon Mar 25 2024

An active cold front is moving toward the local area and will spread
through the area today and tonight with increasing showers and
active thunderstorms over the local waters. The cold front passage
will bring clearing and moderate northerly winds. The low
pressure associated with the front is generating northerly swell
that will move into the local area Tuesday and produce hazardous
seas in the Atlantic waters and the Caribbean passages. Seas will
remain hazardous through at least Thursday.

&&

.BEACH FORECAST...
Issued at 429 AM AST Mon Mar 25 2024

A moderate risk of rip currents will persist along the north coast
today. Although the risk will diminish briefly tonight, it will
return on Tuesday and then become high on Wednesday for the
beaches of Puerto Rica and the northern U.S. Virgin Islands. Beach
conditions on most coasts will continue to deteriorate through
Thursday.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
557 AM AST Tue Mar 26 2024

...New SYNOPSIS, AVIATION, MARINE, BEACH FORECAST...

.SYNOPSIS...
Issued at 523 AM AST Tue Mar 26 2024

A drier airmass with northerly flow will prevail under upper level
high pressure through at least Friday. A weak front will come
through on Saturday and Saturday night with an increased chance of
showers. Then drier air will follow again through mid week next
week.

&&

.SHORT TERM...Today through Thursday...

Calm conditions prevailed during the overnight hours across the
islands. Isolated showers were observed mainly across the open
Caribbean waters and local passages. Light and variable winds
prevailed for most of the night hours except across Saint Thomas
where winds were 15-20 mph. Temperatures were observed in the low
to mid 70s across the coastal and urban portions of the islands,
and in the mid to upper 60s across the higher elevations. These
weather conditions will continue to prevail for the rest of the
morning hours.

Now that the cold front has passed, weather conditions will
gradually improve as dry air filters into the local area. However,
moisture associated to the front may continue to produce isolated
showers across the local waters during the morning hours. As the
day progresses, the drier air will promote fair weather conditions
across much of the region. This pattern will limit the formation
of significant showers for most of the short-term period. The
latest Precipitable Water content Analysis (PWAT) shows values of
0.60 to 0.90 inches until at least Thursday.

The low pressure that carried the cold front over our local area on
Monday, is now located over the central Atlantic. This will result
in light winds from the northwest at 5 to 10 mph. A very similar
weather pattern is expected on Wednesday and Thursday as the drier
and cooler airmass persist over the islands. Overall, temperatures
are expected to range from the mid-80s across the lower elevations
to the mid-70s in the higher elevations.

&&

.LONG TERM...Friday through Monday...

The low pressure that brought the front yesterday will move
southeast until it crosses 60 north Thursday morning around 25
north. The resulting northwesterly flow will bring cooler and
drier air into the area, Tuesday through Friday. Another cold
front will move into the area Saturday and Saturday night, to
produce some showers, but the airmass will only be slightly
cooler and will carry only a little more moisture than the
airmass now in place. This will limit shower activity expected
throughout the period. This is where the GFS and the ECMWF begin
to diverge dramatically. The ECMWF warms up while the GFS
continues the cool air advection out of the western Atlantic. High
pressure at the surface holds in the western Atlantic but is
gradually eroded by a double-barreled low in the Atlantic that
crowds it back onshore in the eastern United States. This leaves
Puerto Rico in light to moderate northerly flow with limited
shower activity.

High pressure at upper levels over the south central Caribbean on
Wednesday will lose most of its strength due a cut-off low that
formed on Monday east of North Carolina and drifted east on
Tuesday and southeast on Wednesday. By Friday it will be about
900 miles northeast of San Juan, Puerto Rico forcing the ridge
into submission. The flattened ridge will pass through the
forecast area on Friday. Another trough at upper levels will
pass through the area Monday.

&&

.AVIATION...
(12Z TAFS)
Issued at 523 AM AST Tue Mar 26 2024

Mainly VFR conditions are expected to prevail across all terminals
during the next 24 hours. Remaining moisture associated to the
passage of a cold front may result in VCSH at TJSJ/TJPS/TIST/TISX
aft 26/14z. Winds will prevail from the NNW btw 10 to 15 kts aft
26/14z.

&&

.MARINE...
Issued at 523 AM AST Tue Mar 26 2024

A northerly swell is already advancing toward the area and will
with the addition of wind waves become hazardous during the next
12 hours. Conditions are expected to be improved by the weekend.

&&

.BEACH FORECAST...
Issued at 523 AM AST Tue Mar 26 2024

Although the early arrival of swell and wave action may be
somewhat delayed it is still expected to be the most significant
part of the weather story. The risk of rip currents will become
high during the next 24 hours and high surf will still develop
with breaking waves of 10 feet or more.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
400 AM AST Wed Mar 27 2024

.SYNOPSIS...

Dry and stable weather conditions are expected to prevail for the
next few days. A weak front will approach the local area from the
northwest on Saturday, increasing the potential for shower
activity. The main hazards for the next several days are marine
and coastal conditions due to the arrival of northerly swells.
Please refer to the marine and beach forecast sections for more
details.


&&

.SHORT TERM...Today through Friday...

While stable conditions are anticipated to persist over the next few
days, passing showers are possible, primarily affecting the northern
regions of Puerto Rico overnight and early morning hours.
Additionally, isolated showers may develop over southern part of
Puerto Rico during the afternoon hours. These showers are not
expected to result in significant rainfall accumulations.

Due to prevailing northerly winds temperature are forecast to be
below normal this time of the year. Overall, temperatures are
expected to range from the mid-80s across the lower elevations to
the mid-70s in the higher elevations.

&&

.LONG TERM...Saturday through Tuesday...

A cold front is forecast to move into the local area by the
beginning of the long-term period. This front will cross the islands
on Saturday morning enhancing the potential for scattered to
numerous showers across the area. However, this front will move
relatively fast and by Saturday night is expected to be out of the
forecast area. The latest Precipitable Water content Analysis is
suggesting values between 1.40 to 1.60 inches during the passing
of the front. By Sunday onwards, a dry airmass will filter into
the region promoting stable weather conditions for much of the
period. Limited or none precipitation is expected. Nonetheless,
passing showers dragged by the trade winds may be observed but
mainly over the regional waters and windward portions of the
islands. A strong surface high pressure located over the western
Atlantic will promote light to moderate winds from the northeast.
By Tuesday, a patch of moisture will approach the region from the
east, therefore, increasing the shower activity across the area.
Overall, warm temperatures will persist throughout the region.
Daytime temperatures will range from the mid to upper 80s across
the lower elevations and in the low 80s across the higher
elevations.

&&

.AVIATION...
(06Z TAFS)

Mainly VFR conditions are expected to prevail across all terminals
during the next 24 hours. Winds will prevail from the North btw 10
to 15 kts aft 27/12z.

&&

.MARINE...

A low-pressure system located approximately 900 miles north of our
local region will persist generating a significant northerly
swell. which commenced impacting the local waters on Tuesday
afternoon. These swells are forecasted to reach their peak between 1
to 3 PM today, gradually diminishing thereafter until Friday.
Another pulse of energy is anticipated to reach our Atlantic local
waters by Sunday,influencing them until Tuesday morning. Winds will
primarily be from the north until Tuesday, when a shift to easterly
winds is expected.

&&

.BEACH FORECAST...

A high risk of rip currents persist along the western, northern, and
eastern coast of Puerto Rico until at least Friday. Additionally, a
High Surf Advisory remains in effect for these areas through
Thursday morning. Culebra, St Thomas, St. John are also
experiencing a high risk of rip currents until at least Thursday.

In the coming days, numerous individuals will flock to our local
beaches, despite the hazardous marine conditions persisting along
the west, north and east coasts. We advise to check out the NWS
marine forecast, visiting beaches along the south side of the islands
and always choosing beaches deemed safe for swimming.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
416 AM AST Thu Mar 28 2024


.SYNOPSIS...

A ridge of high pressure extending across the southwest, along with
an area of low pressure to the north at about 600 miles, will result
in light to moderate northerly winds persisting until the end of the
week and into the weekend. Also this weather scenario will limit
shower activity across the local region until Saturday. On Saturday,
a cold front now located over the eastern U.S. and extending south
to Central America will move ESE and over the local region by
Saturday. This weather feature will increase the shower coverage
late Saturday into early Sunday.

&&

.SHORT TERM...Tonight through Friday...

Throughout the overnight hours, predominantly fair weather
conditions persisted, marked by clear skies and mainly shower free
conditions. The Doppler radar only showed a few showers over the
Caribbean waters. This prevailing pattern is expected to persist
into the afternoon, with a slight potential for isolated showers to
develop over the southern and southeastern portions of Puerto Rico.

The current weather pattern will persist until Saturday,
Characterized by limited shower activity and below normal
temperatures. Northerly winds and mostly clear skies will dominate
the region during this period. However, this weather scenario is
anticipated to shift as a cold front is forecast to move across the
area late Saturday. While models indicate that the moisture
associated to the cold front will swiftly move eastward, there is a
likelihood of increase showers and a slight chance of thunderstorms.

&&

.LONG TERM...Sunday through Wednesday...

The inherited forecast remains unchanged. The latest model guidance
continues to suggest that residual moisture associated with the
passage of the cold front will remain over the area through the
end of the weekend. From Sunday into Monday, a brief dry air mass
will filter across the region, allowing the Precipitable Water
(PW) values to drop from 1.60 to around an inch. This means that
the PW content will go from above-normal climatological levels to
around normal to slightly below-normal climatological levels for
this time of the year. On Sunday, the surface high pressure, now
located over the state of Mississippi, just behind the
aforementioned cold front, will introduce northeasterly light to
moderate winds across the area. Under this wind pattern,
occasional trade wind showers cannot be ruled out of the forecast.
By the beginning of the workweek, the cold front will stall close
to the region, allowing the northeasterly trades to bring back
additional patches of moisture associated with the frontal system
into the area. At this time, the model suggests that the PW values
will stay around an inch/slightly below normal climatological
levels.

A change in weather conditions will occur on Wednesday as a drier
airmass filters across Puerto Rico and the U.S. Virgin Islands.
From midweek onwards, expect the wind to shift and become
easterly, allowing stable and typical weather conditions to
prevail across the islands.

&&

.AVIATION...
(06Z TAFS)

VFR conditions are expected to prevail across all TAF terminals
during the next 24 hours. N-NW winds will prevail through 28/18Z .
No significant rainfall activity is expected.

&&

.MARINE...

A surface high pressure ridge extending across the southwest
Atlantic and a distant area of low pressure north of the region will
promote light to moderate northerly winds through the end of the
week into the weekend. A large northerly swell generated by the
before mentioned low pressure will continue to affect the local
Atlantic waters including all local passages. This swell event
already peak and now is slowly decreasing but dangerous and
hazardous marine conditions will prevail through the weekend.
Another pulse of energy in the form of swells will affect the same
areas early Sunday morning.

&&

.BEACH FORECAST...

On Wednesday, multiple search and rescue operations were conducted
along the northern coast of Puerto Rico due to rough seas and strong
rip currents. There were reports of five search and rescue
incidents, including one drowning at Montones beach in Isabela and
an ongoing search for a person at La Pared beach in Luquillo.
Despite the northerly swell having already peaked, hazardous and
dangerous beach conditions will persist through the upcoming
weekend, with another swell event expected to reach our local
coast on Sunday.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
355 AM AST Fri Mar 29 2024


.SYNOPSIS...

The surface high pressure stretching across the southwest Atlantic,
along with a distant diminishing area of low pressure northeast of
the region, will maintain a north to northwest winds until at least
Saturday. Also this weather scenario will limit shower activity
across the local region until Saturday morning. On Saturday, a cold
front now located over the Atlantic waters east of the continental
U.S. and extending south to Central America will move ESE and over
the local region by Saturday. This weather feature will increase the
shower coverage late Saturday through Sunday morning.Improving
weather conditions from Monday onwards.

&&

.SHORT TERM...Today through Sunday...

Throughout the overnight hours, predominantly fair weather
conditions persisted, marked by clear skies and mainly shower free
conditions. The Doppler radar only showed a few showers over the
Atlantic waters north of St Thomas. This prevailing pattern is
expected to persist into the afternoon, with a slight potential for
isolated showers to develop over the southern and southeastern
portions of Puerto Rico.

The current weather pattern will persist until Saturday,
Characterized by limited shower activity and below normal
temperatures. Northerly winds and mostly clear skies will dominate
the region during this period. However, this weather scenario is
anticipated to shift as a cold front is forecast to move across the
area late Saturday and Sunday morning. While models indicate that
the moisture associated to the cold front will swiftly move
eastward, there is a likelihood of increase showers and a slight
chance of thunderstorms. A much stable and drier airmass will move
across the region therefore limiting the shower development.

&&

.LONG TERM...Monday through Thursday...

On Monday, the surface high-pressure will continue to move
easterly from the western Atlantic, maintaining the northeasterly
winds across Puerto Rico and the U.S. Virgin Islands. The latest
model guidance shows a ridge at the mid-levels along with dry
conditions from 700 to 250 mb through at least the end of the
long-term period. A dry airmass is forecast to move across the
islands during the period. Precipitable Water models suggest
values dropping to around an inch and slightly below the two
standard deviations for this time of the year. By mid-week, expect
the winds to become easterly as the high-pressure system at the
surface continues to move close to the area. With this, expect the
return of typical weather conditions as the trade winds could
bring occasional periods of showers, particularly over the
windward sections of the islands. At this time, we anticipate
limited to no rainfall activity over Puerto Rico and the U.S.
Virgin Islands through the end of the period. Overall, mostly calm
and stable conditions will dominate the forecast areas from Monday
into Thursday.

&&

.AVIATION...
(06Z TAFS)

VFR conditions are expected to prevail across all TAF terminals
during the next 24 hours. N-NW winds will prevail through 29/18Z .
No significant rainfall activity is expected.

&&

.MARINE...

The surface high pressure stretching across the southwest Atlantic,
along with a distant diminishing area of low pressure northeast of
the region, will maintain light to moderate north to northwest winds
until at least Saturday. Although the northern swell event that
affected us for the last few days will gradually diminish by Saturday
morning, hazardous marine conditions will continue through the
weekend. Another north-northwesterly swell is forecast to reach
our local Atlantic waters starting late Saturday afternoon, posing
hazards once again. Therefore, both the general public and
mariners should closely monitor the marine conditions forecast.

&&

.BEACH FORECAST...

Despite the northerly swell will continue to subside, hazardous
beach conditions will persist through the upcoming weekend, with
another swell event expected to reach our local coast between
late saturday afternoon and Sunday morning.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
522 AM AST Sat Mar 30 2024

.SYNOPSIS...

Stable weather conditions are forecasted today as a drier airmass
dominates the CWA. By Sunday into Monday, a surge of moisture
associated with a frontal boundary extending from the western
Atlantic into the Caribbean. As a result, an increase in shower
activity is expected, mostly across northern sections in the early
morning hours, followed by afternoon showers in the interior.
Another north-northwesterly swell will filter into the region,
resulting in building seas again and hazardous coastal conditions.
There is a HIGH risk of Rip currents in effect now across all the
northern coastal areas. Beachgoers are urged to avoid the beaches
along the north coast.

&&

.SHORT TERM...Today through Monday...

Overnight, mostly calm and stable weather conditions prevailed
across Puerto Rico and the U.S. Virgin Islands. The wind flow
gradually shifted from the west-northwest to the north at around 5
mph. Temperature-wise, they were in the upper 60s to low 70s along
the coastal areas, while over the higher terrains, they stayed in
the 70s.

The latest model guidance continues to suggest that a dry airmass
will continue to dominate the forecast area through the morning
hours, resulting in mostly calm and stable conditions during that
time. Nonetheless, by the afternoon into evening hours, expect an
increase in moisture as the cold front system associated with the
low pressure off the Canadian eastern coast moves northeasterly.
Precipitable Water (PW) models show PW content reaching the normal
climatological levels for this time of the year. With the increase
in PW content, expect a change in weather conditions across the
islands by the afternoon hours. At this time, we anticipate periods
of isolation to scattered showers and possibly localized numerous
shower activities, particularly during the afternoon hours. Expect
this weather pattern to continue through the beginning of the
workweek.

A gradual improvement in weather conditions will be seen from Monday
onwards.

&&

.LONG TERM...Tuesday through Saturday...

The long-term forecast remains on track. By Tuesday, an existing
upper-level trough will continue to move southward out of the
forecast area at the upper levels, leaving the region under a more
stable weather pattern with a mid to upper-level ridge in place.
As a result, the weather pattern will be dominated mainly by the
surface features.

From Tuesday into Wednesday, a building surface high pressure
will be the dominant feature across the local region. This surface
ridge will be centered over the western Atlantic and extend into
the Central Atlantic, resulting in east-northeast winds across the
CWA. Embedded in this wind pattern, fragmented moisture from the
previous frontal boundary will move again over the region,
inducing some isolated showers across southwestern areas in the
afternoon. The surface pattern will change as the broad surface
high pressure extends over the Central Atlantic, resulting in
veering winds, becoming more from the east-southeast. With this,
the islands can expect a warmer trend by mid-week, followed by an
increase in tropical moisture across the region. Temperatures
could range from the mid to upper 80s to the lower 90s, and heat
indices near 100-102 Fahrenheit degrees.

A deteriorating trend pattern in terms of the Probability of rain
is forecast from Thursday onwards. According to the recent model
guidance, the surface pattern will lead the approach of a broad
pulse of tropical moisture with a PWAT of 1.70 inches. As a
result, an increase in shower activity is forecast by the end of
the period.

&&

.AVIATION...
(06Z TAFS) Issued at 517 AM AST Sat Mar 30 2024

VFR conditions will prevail across all terminals. N-NE winds will
prevail through 30/23Z. After 30/14Z, winds will increase from 8 to
14 knots. No significant rainfall activity is expected. However, an
increase in shower activity is foreseen after 30/18Z as the frontal
boundary approaches the region.

&&

.MARINE...

Another north-northwesterly swell will continue to spread across
the Atlantic waters today, reaching the local region late this
evening. This will mostly result in building seas up to 8 feet
across the offshore Atlantic waters and nearly 7 feet across the
nearshore Atlantic waters and the Mona Passage. Therefore, several
small craft advisories are in effect, and small craft operators
are urged to exercise caution. Hazardous marine conditions will
persist for the rest of the weekend and into the next workweek. A
pulse of moisture associated with a frontal boundary will enhance
shower activity and gusty winds over the exposed waters.


&&

.BEACH FORECAST...
Hazardous coastal conditions are forecast to persist across the
northern coastal areas of Puerto Rico today. Due to large breaking
waves up to 7 feet in height, a high risk of rip currents
statement is in effect. The risk will remain in place and spread
to other areas by Sunday when the northerly swell's big pulse
moves in and spreads over the Atlantic waters. Beachgoers,
residents, and visitors are urged to avoid the northern coastal
areas. The risk of rip currents across the southern coastal areas
will remain low to moderate.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
515 AM AST Sun Mar 31 2024

.SYNOPSIS...

Increasing moisture is expected today and with chance of shower
and isolated thunderstorms. This activity is forecast to
affect the northern coastal areas in the morning and southwestern
sections of PR in the afternoon. Weather conditions will improve
by midweek as a dry airmass filters inland. The hazardous marine
and coastal conditions will remain through next week.

&&

.SHORT TERM...Today through Tuesday...

Variable weather conditions prevailed over the night hours across
the region. In the early morning hours, radar imagery at Punta
Salinas showed shower activity affecting the northern coastal areas,
moving inland into some central sections. Shower activity also
affected regions across the San Juan Metro area, but so far,
rainfall accumulations have been minimal. Overnight temperatures
were in the mid to upper 70s across the coastal areas and in the mid-
60s across the mountains, with lower temperatures in some isolated
areas near the valleys.

For the rest of the period, a more unstable weather pattern with a
higher likelihood of showers is expected due to the presence of a
mid-to-upper-level trough moving eastward into the region. According
to recent global guidance, instability at the upper level increases,
and mid-level temperatures descend to -8 Fahrenheit degrees . These
unsettled weather conditions will combine with the available
moisture across the region from a cold front, extending from the
central Atlantic into the CWA. By Monday, the cold front is pushed
out by broad surface high pressure over the western Atlantic,
inducing northeasterly winds on Monday. Although instability is
present, water content values and coverage remain quite low, as
suggested by the GOES Satellite-Derived Imagery, with PWAt at 1.35
inches. Based on the actual conditions, shower activity is forecast
for today, especially in the afternoon, with the diurnal heating . A
few isolated thunderstorms can develop with the strongest showers.

A shift to a more easterly wind pattern is forecast by Tuesday as
the broad surface high pressure moves further into the Central
Atlantic. Similar weather features will be in place, and enough low-
level humidity will be present for another round of showers,
especially in the late morning into the afternoon, with the bulk of
the showers over the central interior. Given the expected weather
conditions, residents and visitors could expect minor and urban
flooding, especially in poor drainage areas across the western and
western interior areas.

&&

.LONG TERM...Wednesday through Sunday...

On Wednesday, a surface high-pressure system will dominate the
forecast area, allowing the east-northeast winds to promote
seasonal weather conditions. This weather feature will allow
showers embedded in the trade winds to filter across Puerto Rico
and the U.S. Virgin Islands from time to time. At this time, the
model suggests fragments of moisture from the previous frontal
boundary brought back into the area by prevailing wind flow. In
the morning, expect showers to filter along the northeastern
coastal areas of PR and the USVI, and by the afternoon hours, they
will move/ develop over the southwestern sections of Puerto Rico.

From late mid-week into Thursday, the previously mentioned high
pressure will extend over the Central Atlantic, resulting in veering
winds, becoming more from the east-southeast. Therefore, the
islands are foreseen to experience a warmer trend followed by an
increase in tropical moisture across the region. At this time, we
are forecasting temperatures to range in the upper 70s to 80s
along the higher terrains and in the mid to upper 80s and
localized areas along the coast reaching the lower 90s. With this
weather pattern, the citizens and visitors of the islands could
experience heat indices around 100 - 102 degrees Fahrenheit.

We anticipate a change in weather conditions by the early hours of
Friday into the weekend. The latest precipitable water (PW) model
suggests the PW content reaching around normal climatological
levels for this time of the year, meaning an increase in shower
activity. As the east-southeasterly winds prevail, a broad pulse
of tropical moisture will continue to filter the region.

&&

.AVIATION...
(06Z TAFS)

VFR conditions will persist for all the TAF sites during the period.
SHRA and TSRA from 31/16Z might result in some brief MVFR conditions
near TJBQ, TJSJ, and TJPS with low ceilings and reduced VIS. Across
the mountains from 31/16-31/23Z, FL020 & FL030 are possible due to
the TS. Winds will continue from the N-NE, increasing by 31/15Z up
to 15 knots with gusty wind. Surface winds will increase even more
from 01/00Z.

&&

.MARINE...

A north-northwesterly swell will continue to reach the local
Atlantic waters today, resulting in seas building between 7 to 8
feet. Northeasterly winds will become moderate to locally fresh,
through at least early this upcoming workweek, as a surface high
builds across the western Atlantic. With increasing winds and swell,
rough and hazardous seas will affect the Atlantic waters and the
local passages through at least Monday, and several Small Craft
Advisories are in effect. An approaching frontal boundary will sink
southwards and increase the potential for shower and isolated
thunderstorm development over the local waters today. Both the
general public and mariners should closely monitor the forecast
marine conditions.

&&

.BEACH FORECAST...

Hazardous coastal conditions are forecast to persist across the
western, northern, and eastern coastal areas of Puerto Rico
through late Monday night. For that reason, a high risk of rip
current remains in effect for those areas through late Monday
night. This hazardous conditions will spread across the beaches of
Culebra, St. Thomas, and St. John by tonight. Beachgoers,
residents, and visitors are urged to avoid the western, northern,
and eastern coastal areas. The risk of rip currents across the
southern coastal areas of Puerto Rico will remain low to moderate.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
539 AM AST Mon Apr 1 2024

SYNOPSIS...

A north-northwesterly swell is promoting hazardous marine and
coastal conditions. A High Surf Advisory is in effect for the
northern coastline of Puerto Rico, from Rincon to Fajardo,
Culebra, and St. Thomas through at this afternoon. A High Risk of
Rip Currents is in effect through at least tomorrow night, for
the aforementioned areas. This swell is promoting seas between 6
and 8 feet across the Atlantic Waters and Caribbean Passages
where several Small Craft Advisories are in effect through at
least tomorrow morning.

Variable to showery weather will continue today as moisture
fragments from a past frontal boundary continue to filter in,
steered by northeasterly winds. Environmental conditions are
expected to become more favorable for the formation of showers and
possibly isolated thunderstorms today. A warming trend is
anticipated for the latter part of the week as winds turn from the
southeast.

&&

SHORT TERM...Today through Wednesday...

An overnight radar and satellite imagery analysis indicated
persistent passing shower activity affecting northern Puerto Rico.
In the last 6 hours, surface observing stations have reported up to
a quarter of an inch in isolated areas. Variable cloudy skies
prevailed in other areas, including the US Virgin Islands, with some
clearing observed at times. Given these conditions, as reported by
official sites, overnight temperatures ranged from 62 degrees in
higher elevations to 78 degrees across lower elevations. Winds were
generally northeasterly at 10-15 mph with higher gusts across
northern and eastern Puerto Rico and the local islands, but light to
calm and variable elsewhere.

According to the latest model guidance, significant fluctuations in
moisture levels are anticipated throughout the short-term forecast.
Following a brief period of decreased moisture earlier today,
precipitable water values are projected to reach approximately 1.4
inches, which is within typical seasonal levels, later this
afternoon. In the meantime, environmental conditions are expected to
become more favorable for the formation of showers and possibly
isolated thunderstorms due to a mid- to upper-level trough moving
eastward across the region, with mid-level temperatures descending
between -8 and - 9 degrees Fahrenheit. Given these conditions,
there is a likelihood of limited risk of excessive rainfall,
particularly leading to ponding of water on roads and poorly drained
areas. Localized urban and small stream flooding may occur.
Additionally, there is a likelihood for limited wind risk impacts,
driven by increasing east to northeasterly winds associated with a
broad high pressure system spreading across the western Atlantic.
Sustained wind speeds are expected to peak in the 15-20 mph range,
with higher gusts primarily affecting coastal areas and the local
islands.

The forecast for Tuesday suggests a similar weather pattern,
featuring normal moisture levels and marginally conducive
environmental conditions for shower development. Stable and calm
weather conditions will likely return on Wednesday, with a drier-
than-normal airmass, influenced by the flow generated by the
aforementioned high pressure system, displaces the remnants of the
cold front from the area. Simultaneously, the mid-to-upper level
trough will shift away, leading to rapidly increasing mid-level
temperatures. Consequently, the likelihood of shower activity is
expected to diminish, with decreasing probabilities and coverage
anticipated for Tuesday and Wednesday. In this anticipated
scenario, typical seasonal temperatures are forecasted for today and
Tuesday, followed by a slight warming trend on Wednesday as winds
shift to a more southeasterly direction.

&&

LONG TERM...Thursday through Monday...

A broad high pressure, now building over the west and central Atlantic,
will continue to extend further to the central Atlantic, resulting
in veering winds, becoming more from the east-southeast from the
beginning of the long-term period through the weekend. Consequently,
expect a warming trend across the islands and an increase in
tropical moisture. Currently, we are forecasting temperatures to
range in the upper 70s to 80s along the higher terrains and in the
mid to upper 80s and localized areas along the coast, reaching
the lower 90s. With this weather pattern, the citizens and
visitors of the islands could experience heat indices around 100 -
102 degrees Fahrenheit, mainly during the end of the week. The
latest precipitable water (PW) model suggests the PW content
reaching around normal climatological levels for this time of the
year, meaning an increase in shower activity. This will drive a
pattern of passing windward showers across eastern Puerto Rico and
the USVI, followed by afternoon convection mainly across the
interior to the western section of PR. Still, accumulations should
not be too significant as the upper level will remain stable with
dry air and an upper-level ridge in place. By early next week,
additional moisture from an approaching cold front should merge
with the present moisture and support better rain chances.

&&

AVIATION...

VFR conditions will persist for all the TAF sites during the period.
SHRA and TSRA from 01/16Z might result in brief MVFR conditions near
TJSJ and TJPS with low ceilings and reduced VIS. Winds will continue
from the N-NE AT 10-15 kts, increasing to 15-20 kts with gusty winds
after 01/12Z.

&&

MARINE...

A north-northwesterly swell is promoting seas between 6 and 8 feet
across the Atlantic Waters and Caribbean Passages through early
Tuesday. A surface high pressure building from the western to central
Atlantic will promote moderate to locally fresh northeasterly winds
through at least Monday. Frontal moisture remnants interacting
with an upper level trough will maintain the potential for shower
development across the regional waters today. Both the general
public and mariners should closely monitor the forecast marine
conditions.

&&

BEACH FORECAST...

A High Surf Advisory for the northern coastline of Puerto Rico,
from Rincon to Fajardo, and Culebra have been extended through
this afternoon due to breaking waves up to 11 feet. In addition,
St Thomas and St John were added. A High Risk of Rip Currents is
in effect through at least late tomorrow night, for the aforementioned
beaches as well as for the northern USVI. Beachgoers, residents,
and visitors are urged to avoid the western, northern, and eastern
coastal areas. The risk of rip currents across the southern
coastal areas of Puerto Rico will remain low to moderate.

Rip currents that can sweep even the best swimmers away from shore
into deeper water where it becomes difficult to return to safety.
High waves that can wash over jetties and sweep people and pets
onto jagged rocks. Rough surf may also knock you down. Minor
beach erosion and localized coastal flooding may occur due to high
surf.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
511 AM AST Tue Apr 2 2024

.SYNOPSIS...

Variable weather conditions are expected to continue today, the
rain in the southwest could be strong enough to cause some ponding
of water in roadways. Stable and calm weather conditions on Wednesday
with the arrival of a drier air mass. A warming trend is anticipated
for the latter part of the week as wind flow turns from the southeast
and low-level tropical moisture increases across the region.

&&

.SHORT TERM...Today through Thursday...

Passing showers have been moving across eastern and northern Puerto
Rico, and in the waters around the U.S. Virgin Islands during the
night hours. Recent infrared and precipitable water-derived
satellite imagery show that some clouds will continue to stream
across the area this morning. However, this patch of moisture is
shallow, and only stretch to around 700 mb, since a ridge and dry
will begin to dominate up to the mid-levels. The high resolution
models show moderate rainfall accumulations reaching eastern Puerto
Rico and the Virgin Islands during the day today, with stronger
showers firing up in the southwest this afternoon. The rain in the
southwest could be strong enough to cause some ponding of water in
roadways. The high pressure will maintain breezy conditions too,
with a steering flow around 15-20 knots at the surface.

By the middle of the week, conditions will dry out as the ridge
holds, and a trade wind cap inversion develops around 750 mb.
Moisture will be below normal, and temperatures at 500 mb will be
warmer than normal, so rainfall activity will be very limited.

The forecast becomes more interesting on Thursday. As a cold front
leaves the eastern coast of the United States, it will push the high
pressure eastward. The trade winds will slow down considerably and
shift from the south all the way into the mid-levels of the
atmosphere. In response, 925 mb temperatures will climb over two
standard deviation above the climate normals. Additionally, some
moisture will jump from the Caribbean Sea into the region,
increasing moisture levels a little. In simple words, these factors
will result in hot conditions, with temperatures reaching the low
90s and heat indices above 100 degrees for urban and coastal areas.
The probability of precipitation is also expected to increase, with
showers moving across southern Puerto Rico and around the U.S.V.I.

&&

.LONG TERM...Friday through Tuesday...

According to the latest model guidance, broad surface high
pressure should be over the central Atlantic on Friday, promoting
southeasterly winds across Puerto Rico and the U.S. Virgin Islands
through the weekend. That pattern will increase tropical moisture
across our CWA. The latest precipitable water (PWAT) model suggests
that the PWAT content will reach above-normal climatological
levels starting Friday. That will drive a pattern of passing
windward showers across eastern Puerto Rico and the USVI, followed
by afternoon convection mainly across the interior to the western
section of PR through the weekend. At the mid-levels, high
pressure will dominate at the end of the week, helping to suppress
the shower's development. As a result, we are not expecting
significant accumulations each day, but we will keep monitoring
the guidance for any updates. At the same time, this weather
pattern will promote a warming trend across the region. Currently,
we forecast temperatures to range from the upper 70s to upper 80s
along higher terrain and into the low 80s and localized areas
along the coast, reaching into the lower 90s. With this weather
pattern, citizens and visitors could experience heat indices
between 100 and 102 degrees Fahrenheit, especially on Friday and
Saturday.

On Sunday, winds should be very light across the region ahead of
an approaching cold front. By early next week, winds should turn
from the east-northeast as the aforementioned frontal boundary
approaches to the north of the forecast area and another surface
high pressure builds over the western Atlantic. That will bring
additional moisture, increasing the chance of scattered showers
across the local area at the beginning of the work week.

&&

.AVIATION...
(06Z TAFS)

VFR conditions will persist for all the TAF sites during the period.
SHRA and TSRA from 31/16Z might result in some brief MVFR conditions
near TJBQ, TJSJ, and TJPS with low ceilings and reduced VIS. Across
the mountains from 31/16-31/23Z, FL020 & FL030 are possible due to
the TS. Winds will continue from the N-NE, increasing by 31/15Z up
to 15 knots with gusty wind. Surface winds will increase even more
from 01/00Z.

&&

.MARINE...
Issued at 503 AM AST Tue Apr 2 2024

A slowing fading northerly swell will continue to promote seas
between 6 and 8 feet across the Atlantic Waters and Caribbean
Passages through this morning. A surface high pressure building
across the west and central Atlantic will maintain light to
moderate east winds through the next several days. Residual
moisture will maintain the potential for shower development across
the regional waters today.

&&

.BEACH FORECAST...
Issued at 503 AM AST Tue Apr 2 2024

Beachgoers, residents, and visitors, a High Risk of Rip Currents
is in effect through this afternoon for the northern coastline of
Puerto Rico from Aguadilla to Fajardo, Culebra, St. Thomas and St.
John. The risk of rip currents across the southern coastal areas
of Puerto Rico will remain low to moderate.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
512 AM AST Wed Apr 3 2024

.SYNOPSIS...

More stable and calm weather conditions are forecast today and
Thursday with the arrival of a drier air mass, however, strong
heating should aid in the development of showers activity over
northwestern Puerto Rico. A warming trend is anticipated for the
latter part of the week as wind flow turns from the southeast and
moisture increases, along with better chances for showers. Expect
improving marine conditions during the next several days with
seas remaining at 5 feet or below.

&&

.SHORT TERM...Today through Friday...

A patch of clouds moved across the islands during the night hours.
Some showers reached eastern and northern Puerto Rico, and the
surrounding of the Virgin Islands. These rains were not too strong,
but left wet roads in these areas.

A surface high pressure continues to migrate eastward just north of
the islands. This feature will maintain the trade winds from the
east today, at speeds of 15 to 20 mph. At the mid levels, a ridge
will hold, with a very dry air mass above 850-750 mb. This means
that the area of moisture will remain trapped in the lower levels of
the atmosphere. As the day progresses, precipitable water values
will continue to fall below the climatological value, hence the
frequency of showers will decrease. However, strong heating should
aid in the development of additional, stronger, activity over
northwestern Puerto Rico.

On Thursday, as the high continues to migrates toward the east, the
wind flow will begin to shift from the southeast at the surface, and
more from the south or southwest at the mid-levels. A trade wind cap
inversion will develop around 850 mb, so Thursday should be the
driest day of this period. Moisture will lift from the south on
Friday, increasing the frequency of showers. However, the main
effect of southerly winds will be temperatures much higher than
normal, with maximum values reaching the low 90s, and heat indices
above 102 degrees across most urban and coastal areas. The upper
dynamics will not work against shower development, but low level
moisture and heating should be enough to fire up showers across the
Cordillera Central. Additionally, with winds out the southeast at
the surface, and out of the southwest a little higher in the
atmosphere, these showers should move toward northwestern and the
northern half of Puerto Rico in the afternoon hours.

&&

.LONG TERM...Saturday through Wednesday...

For the beginning of the long-term forecast, model guidance is
suggesting the high pressure at the surface should be located
towards the east of the Atlantic, promoting prevailing
southeasterly winds across Puerto Rico and the U.S. Virgin Islands
through the weekend. That pattern will bring an increase in
tropical moisture content across our CWA. The latest precipitable
water (PWAT) model suggests that the PWAT content will remain
above normal climatological levels during the weekend. At the mid-
levels, high pressure will dominate, helping to suppress the
shower's development. However, diurnal heating and local effects
will drive a pattern of passing windward showers across eastern
Puerto Rico and the USVI, followed by afternoon convection mainly
across the interior to the western section of PR through the
weekend.

The warming trend will continue through the weekend across the
region, which is the main concern. Currently, the forecast is
showing temperatures ranging from the upper 70s to upper 80s along
higher terrain and into the low 80s and localized areas along the
coast, reaching into the lower 90s. At this time, Saturday seems
to be the day with the highest heat indices mainly in the metro
area, with values between 102 to 106 degrees F.

On Sunday, a frontal boundary; currently over the Southeastern
U.S., is forecast to be near Hispanola. By early next week, winds
should increase and turn from the east-northeast as the
aforementioned frontal boundary approaches from the north and
another broad surface high pressure builds over the western
Atlantic and drives the wind flow. Additional moisture will merge,
increasing the chance of scattered showers across the local area
at the beginning of the work week.

&&

.AVIATION...
(TAFs 06z)

Mainly VFR conditions expected today. Passing SHRA will continue
across the Caribbean and Atlantic waters, but impacts to operations
are expected to be minimal. After 18Z, additional SHRA expected to
develop near TJBQ, with brief periods of reduced VIS and low ceiling
possible. Winds will be from the ESE at 14-18kts, gusting up to 25
kts from 14-22Z. Winds will slow down after 22Z.

&&

.MARINE...

Small craft operators should exercise caution across northern
coastal waters of Puerto Rico today due moderate to locally fresh
easterly winds. Later today and continuing through the weekend,
expect favorable conditions for small craft, with seas remaining at
5 feet or below. A surface high pressure moving eastward across the
Atlantic will promote gentle to moderate easterly winds through the
end of the week. Winds are forecast to weaken and become more
southeasterly over the weekend. Isolated to scattered showers will
be possible across the local waters, mainly by the end of the week.

&&

.BEACH FORECAST...

A High Risk of Rip Currents remains in effect for the northern
coastline of Puerto Rico; from Aguadilla to Fajardo, and Culebra
through late tonight. The risk should remain moderate the rest of
the forecast period, but we will continue to closely monitor the
conditions for any update. For more information and details about
the latest forecast please refer to the Surf Zone Forecast
(SRFSJU), and the Coastal Hazard Message product (CFWSJU).

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
513 AM AST Thu Apr 4 2024

.SYNOPSIS...

An abnormally warmer trend will prevail the rest of the week;
thus, expect maximum temperatures near the low 90s in urban and
coastal areas, with heat index values surpassing 100 degrees
Fahrenheit each afternoon. A frontal boundary will reach the
islands by the end of the weekend into next week, promoting an
increase in the available moisture and a possible relief to the
warmer pattern. If the model guidance is correct, we may see
moisture erosion by mid-next week and below normal temperatures as
the remnants of the front sink southward near the Northeast
Caribbean.

Beachgoers, although marine conditions are improving, the risk of
rip currents along the Atlantic coastlines will be predominantly
moderate; we urge you to exercise caution.

&&

.SHORT TERM...Today through Saturday...

Calm weather conditions prevailed during the overnight hours across
the islands. The Doppler radar only showed a few showers over the
eastern sector of Puerto Rico and the local northern waters.
Temperatures were observed in the low to mid-70s across the coastal
and urban portions of the islands and in the mid to upper 60s across
the higher elevations.

A surface high pressure continues to dominate the weather pattern
across the region while migrating into the eastern Atlantic. This
feature will aid in shifting winds from the southeast at the
surface. Based on the latest model guidance, PWAT values are
expected to decrease today to around 1 inch, which is below normal
according to climatology. However, diurnal heating and local effects
may result in some afternoon showers across the northwest sector of
Puerto Rico. Given that stable conditions and drier air are holding
in the mid-levels, no significant rainfall accumulations are
expected today, and should be the driest day of this period.

By Friday into the weekend, the southeasterly winds will cause an
increase in moisture content across the islands, resulting in a
better chance for showers. That will drive a pattern of passing
windward showers across eastern Puerto Rico and the USVI, followed
by afternoon convection mainly across the interior to the western
section of PR. However, the main weather effect of the wind flow and
moisture will be warmer-than-normal temperatures for this time of
the year; starting today and prevailing through the weekend, with
maximum values reaching the lower 90s and heat indices above 102
degrees across most urban and coastal areas. Some coastal areas may
reach the mid-90s. We encourage residents and visitors to remain
informed with the latest forecast, limit sun exposure for long
periods, wear sunscreen and stay hydrated through the weekend.

.LONG TERM...Sunday through Thursday,

On Sunday, a short wave trough aloft will continue to swing
across the region, promoting somewhat unstable conditions.
Meanwhile, the approaching frontal boundary and pre-frontal trough
interacting with the surface high pressure across the eastern
Atlantic will promote a southerly wind flow and moisture pooling
near the Northeast Caribbean. This weather pattern could result in
above-normal temperatures if rain does not develop across the
region (especially in the USVI and northern sections of PR), but
afternoon convection under a weak steering southeasterly wind flow
could promote slow-moving rain activity across the interior and
mountain areas in PR.

The frontal boundary will linger near the region through
Wednesday when model guidance forecasts a FROPA, which is somewhat
atypical for this time of the year. Meanwhile, a mid-level high
pressure and an upper-level ridge will build across the Northeast
Caribbean from late Sunday night or early Monday onward, which
could make it difficult to organize deep convection. However, the
above-normal moisture content that the lingering frontal boundary
could provide would result in showery weather, especially in the
windward sections. If this solution is correct, below-normal
temperatures could result in pleasant temperatures the first part
of next week. Below-normal temperatures and moisture could
develop Wednesday through Thursday after the frontal area sinks
into the Caribbean.

&&

.AVIATION...
(06Z TAFS)

Mainly VFR conditions are expected across all TAF sites today.
After 04/17Z, VCSH are expected to develop near TJBQ. However, no
significant impacts are anticipated. Winds will prevail mainly
from the ESE with afternoon sea breeze variations at 13-16kts,
gusting up to 25 kts from 13-22Z. Winds will slow down around 22Z
into the evening.

&&

.MARINE...
A surface high pressure moving eastward from the central to eastern
Atlantic will promote gentle to moderate east to southeasterly winds
through the end of the week. A cold front near the US Eastern
Seaboard will move eastward across the Western Atlantic, approaching
the Northeast Caribbean by the end of the week and into early next
week.

Although a northerly swell will continue to affect the local
waters through through the weekend, expect favorable conditions
for small craft starting, with seas remaining at 5 feet or below.

&&

.BEACH FORECAST...
Although conditions along the north-facing beaches are improving,
we encourage all beachgoers to exercise caution across the
Atlantic Coastline, as the risk will remain moderate throughout
the period. The Caribbean Coastline and south-facing beaches have
a low risk of rip currents throughout much of the period.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
511 AM AST Fri Apr 5 2024

.SYNOPSIS...

The southeast winds will bring near-to-above-normal moisture,
promoting abnormally warmer heat indices across Puerto Rico and
the U.S. Virgin Islands. A frontal boundary extending from the
western Caribbean into the west of the Atlantic will slowly
approach the northeast Caribbean during the weekend, meandering
north of the islands Sunday and Monday and sinking southward while
promoting a showery pattern early next week. This will be
accompanied by pleasantly cooler temperatures, offering a
comfortable start to the next week.

For the safety of all beachgoers, it's crucial to exercise
caution across the Atlantic Coastline due to a moderate risk of
rip currents.

&&

.SHORT TERM...Today through Sunday...

Quiet weather conditions prevailed during the overnight hours across
the islands. Temperatures were observed in the mid to upper 70s
across the coastal and urban portions of the islands and in the mid
to upper 60s across the higher elevations. Light winds prevailed,
mainly with an easterly to southeasterly component.

Not a lot of changes were made to the short-term forecast as much
remains on track. Synoptically, the high surface pressure continues
to dominate weather conditions across the region as it migrates
further toward the eastern Atlantic. This feature will help the
winds become southeasterly at the surface and gradually increase the
moisture content across the forecast area. The latest precipitable
water models show precipitable water values around normal
climatological levels today and increasing to above normal by this
evening into the weekend. That will drive a pattern of passing
windward showers across eastern Puerto Rico and the USVI, followed
by afternoon convection mainly across the Coordillera Central to the
western section of PR from today onwards. In addition, a warming
trend will continue through Sunday. Warmer-than-normal temperatures
are anticipated for this time of the year, with maximum values
reaching the lower 90s and heat indices above 102 degrees today
across urban and coastal areas of north central and western Puerto
Rico, as well in Vieques and St Croix. Saturday should be the warmest
day of this period. We encourage residents and visitors to remain
informed with the latest forecast, limit sun exposure for long
periods, wear sunscreen, and stay hydrated throughout the weekend.
On Sunday, a short wave trough aloft will continue to swing across
the region, promoting somewhat unstable conditions.

.LONG TERM...Monday through Friday...

A frontal boundary lingering north of the islands will increase
the available moisture from near to above-normal climatological
values (based on the latest GFS solution) under a northeast-to-
north wind flow, promoting below-normal temperatures. The frontal
boundary will sink southward, crossing Puerto Rico and the U.S.
Virgin Islands Tuesday, while a surface high pressure behind the
front builds across the Central Atlantic. This surface high will
induce a northeasterly wind flow, pooling additional moisture into
the region and promoting trade wind showers on Wednesday. Under
this wind flow, the bulk of moisture should located across the
eastern Caribbean, south of PR/USVI. Additionally, pleasant below-
normal temperatures could prevail next week under this possible
weather pattern.

A mid-level high pressure will create somewhat hostile
environmental conditions next week to promote widespread deep
convection. Regardless of the mid-level high pressure, showery
weather with periods of moderate to locally heavy rain could be
anticipated if model guidance is right, especially next Tuesday.

A more typical weather pattern may evolve after the trade winds
return on Thursday. These winds promote the usual trade wind
showers during the evening and morning hours, followed by
afternoon convection due to sea breeze variations and local
effects.

&&

.AVIATION...
(06Z TAFS)

Mainly VFR conditions are expected across all terminals, with
prevailing SE winds reaching speeds of up to 10-15 knots, with some
higher gusts possible and sea breeze variations. SCT-SHRA after 14Z
may cause VCSH across TJSJ and TJBQ. However, no significant impacts
are anticipated.

&&

.MARINE...

A frontal boundary extending from the western Caribbean into the
western Atlantic and a surface high pressure located from the central
to eastern Atlantic will promote a gentle to moderate southeast wind
flow across the islands. The frontal boundary will linger north
of the islands Sunday and Monday, promoting unsettled weather
conditions, and as the remnants of the frontal boundary sink
southward winds will become north to northeast late Monday onward.
A long period northerly swell will arrive by around late Tuesday,
promoting hazardous seas.

&&

.BEACH FORECAST...

Although conditions along the north-facing beaches are improving,
we encourage all beachgoers to exercise caution across the
Atlantic Coastline, as the risk will remain moderate throughout
the period. The Caribbean Coastline and south-facing beaches have
a low risk of rip currents throughout much of the period.

Another long-period northerly swell and increasing winds may
result in hazardous coastal conditions from mid-next week onward.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
502 AM AST Sat Apr 6 2024

.SYNOPSIS...

A weak southeast wind flow and near-to-above-normal moisture will
continue to promote abnormally warmer heat indices across Puerto
Rico and the U.S. Virgin Islands. The weak steering winds combined
with local effects and sea breeze variations will result in
scattered to widespread afternoon convection across the interior
and mountain areas, spreading to the surrounding coastal areas. A
cold front slowly approaching from the west will linger north of
the islands Sunday and Monday, sinking southward while promoting a
showery pattern early next week. The cold air mass behind the
remnants of the front will result in pleasantly cooler
temperatures, offering a comfortable start to the upcoming week.

Exercise caution across the Atlantic Coastline due to the moderate
risk of rip currents for the safety of all beachgoers.

&&

.SHORT TERM...Today through Monday...

Fair overnight conditions prevailed across the islands. Reported
minimum temperatures were in the mid to upper 70s across lower
elevations of the islands and in the mid to upper 60s across higher
elevations of Puerto Rico, winds were up to light and variable.
Current satellite derived precipitable water (PWAT) values indicates
gradually increasing moisture across the islands, from 1.49 to 1.66
inches (high end of normal values for this time of the year).

At surface level, a high pressure system over the central to eastern
Atlantic will continue to move eastward and a frontal boundary will
continue to approach the the region from the west, promoting
relatively weak southeasterly winds across the islands. This
wind flow will continue transporting moisture from our south into
the islands. PWAT values will remain at normal to above normal
values through the short term period. Most available moisture
should remain below 500 mb through the period. In the mid levels,
high pressure will dominate the islands, although a weak mid- to
upper- level trough will move north of the area during the
weekend. The aforementioned frontal boundary and pre frontal
trough will continue to approach the area during the period, with
the boundary moving close to the region late in the period.
Current model guidance indicate the moisture associated with the,
by then, weak boundary persisting through the end of the short
term period, gradually moving south of the islands as steering
flow has a more northerly component on Monday.

Southerly winds and increasing moisture will promote warm to hot
temperatures today, with highs reaching around the low 90s along
coastal areas. A limited heat risk will be in effect, due to
forecasted heat indices above 102 degrees across several urban and
coastal areas. Residents and visitors should limit sun exposure for
long periods, wear sunscreen, and stay hydrated. This diurnal
heating, along with available moisture and local effects will
promote afternoon convective activity along the Cordillera, mainly
drifting northward and promoting a limited rainfall risk. Afternoon
convective activity will be present each day in the short term
period, along with showers affecting sectors of windward areas.

.LONG TERM...Tuesday through Saturday...

Still, model guidance shows the remnants of the cold front
sinking southward into the eastern Caribbean while pooling
additional near-to-above-climatological Total Precipitable Water
amounts over Puerto Rico, the U.S. Virgin Islands, and surrounding
waters. Additionally, possible breezy to locally strong trade
winds behind the front will promote moisture convergence over the
region, which may result in showery weather on Tuesday and
Wednesday. At this time, Tuesday will be the wettest day, as model
guidance still suggests the bulk of moisture moving to the south
of the area on Wednesday. We could also observe near-to-below-
normal temperatures as a somewhat cooler air mass behind the front
set over the islands.

A surface high pressure behind is forecast to build across the
Central Atlantic, promoting breezy to locally strong trade winds
in the second part of the upcoming week. Historically speaking,
under this trade wind pattern, moisture pools across the region,
which brings the arrival of frequent showers, especially across
the windward sections. Near-to-below-normal temperatures could
also prevail this part of the week.

It is important to keep in mind that regardless of the mid-level
high pressure expected to hold over the Northeast Caribbean, the
showery weather creating periods of moderate to locally heavy rain
may evolve next week.

Moisture associated with the old remnants of the cold front,
currently approaching the islands from the west, could arrive as a
trade wind perturbation, producing showery weather on Friday and
Saturday.


&&

.AVIATION...
(TAFs 06z)

Mainly VFR conditions across the terminals,
with SE winds up to 10-15 kts after 06/14Z with some possible higher
gusts and sea breeze variations. Shower activity along the
Cordillera after 06/15-16Z could promote VCSH across TJSJ and TJBQ.

&&

.MARINE...

An approaching cold front from the west and a surface high pressure
anchored off to the northeast of the Northeast Caribbean is
promoting a light southeast wind flow. The frontal boundary will
meander north of the islands Sunday and Monday, promoting unsettled
weather conditions. Expect north to northeast fresh winds and choppy
seas as the remnants of the frontal boundary north of the islands
sink southward into the Caribbean from late Monday onward. Choppy
seas and another long-period northerly swell will promote hazardous
marine conditions by mid-week.

&&

.BEACH FORECAST...

A small northerly swell and locally generated wind seas are
creating a moderate risk of rip currents along the north and east
facing beaches in Puerto Rico, Culebra and St Croix. Therefore,
we encourage all beachgoers to exercise caution across the
Atlantic Coastline.

The risk will persist moderate throughout Tuesday evening, when
combined choppy seas and a long period northerly swell will
increase the risk to high across most of the local beaches in PR
and the U.S. Virgin Islands. The Caribbean Coastline and south-
facing beaches will have a low risk of rip currents through at
least Thursday.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
517 AM AST Sun Apr 7 2024

.SYNOPSIS...

A Heat Advisory has been issued for sectors of northern and
western coastal and urban areas of Puerto Rico, from 10 AM to 5 PM
AST. Please refer to the latest NPWSJU & NPWSPN for more
information and precautionary/preparedness actions. A cold front
is slowly approaching from our west and will linger north of the
region before sinking southward and promoting a more showery
weather pattern through midweek. Remnants of this feature will
then increase rain chances during the next weekend. As winds turn
from the east-northeast and increase by Tuesday onwards, more
pleasant temperatures are forecast. Marine and coastal, however,
conditions will deteriorate Tuesday onwards.

&&

.SHORT TERM...Today through Tuesday...

Calm weather conditions prevailed overnight, with low temperatures
remaining warmer than usual, especially across urban and coastal
areas, regarding the mostly clear to partly cloudy skies we
observed. Shower activity increased from the Caribbean waters as the
weak southeasterly winds brought them into the region. Some showers
moved inland across the windward sections of southeast PR, St Croix,
and St Thomas, while the radar detected little or no rain elsewhere.

As the day began warmer than usual, above-normal heat indices will
likely result throughout the day, especially by mid-morning and the
afternoon, due to the combination of maximum temperatures in the low
90s and above-normal moisture content. As a result, a Heat Advisory
was issued for the coastal and urban sections of portions of PR.

A prefrontal trough near the region, associated with the approaching
frontal boundary, combined with local effects, diurnal heating, sea
breeze, and weak steering winds, will result in strong convection
across the interior and mountain areas, spreading into the
surrounding coastal regions from mid-morning into the afternoon.
Under the southeasterly winds flow, the El Yunque streamer may aid
in forming strong showers and one or two thunderstorms across the
San Juan Metropolitan area, too. Rainfall amounts, especially along
the mountain areas and interior sections and near isolated urban
areas, may range between 1 and 2 inches with isolated higher
amounts. Therefore, we may not rule out urban and small stream
flooding with the most persistent rainfall activity.

GFS guidance suggests near to above-normal Total Precipitable Water
(TPW) values over the region late tonight into Monday as the
remnants of the cold front with its prefrontal surface trough linger
north of the islands and slowly sink southward to cross into the
Caribbean. Wind will slowly shift from the north to the northeast on
Monday, ending the warm trend we have observed since the last
Thursday. Under this weather pattern, wet and unstable conditions
may extend into Monday, resulting in another round of 1 to 2
additional rainfall amounts, as the National Blend of Models
suggests. However, this time, the highest accumulations may be
observed across the southern slopes of PR and surrounding areas.
This activity may result in water ponding in poorly drained areas
and urban and small stream flooding, especially with the most
intense afternoon convection.

Below-normal temperatures may extend into Tuesday as the cold front
sinks southward, pushing the cold air mass behind the remnants of
the front over the PR and the USVI. The bulk of moisture may set
over the region between eastern PR and the USVI, where we may
observe the best chance for shower development from late Monday
night into Tuesday, when between one and two inches of additional
rain may fall.


.LONG TERM...Wednesday through Sunday...

The long term forecast remains on track. At surface level, a high
pressure system, will build across the Central Atlantic, and
gradually spread eastward. This system will promote breezy to
locally strong winds through the period, generally from the east-
northeast. By midweek, moisture related to a past frontal
boundary, should be moving south of the region, but still
maintaining normal to above normal precipitable water (PWAT)
values. Model guidance suggest a drying pattern from Thursday
morning through Friday morning. Remnants of the past frontal
boundary will then be steered by the east-northeast winds and
reach our region from the east, possibly as a trade wind
perturbation, and increase moisture (to up to above normal PWAT),
rain chances and promote variable to showery weather Friday and
throughout the weekend. Most available moisture should stay below
500 mb during the next weekend. A mid level ridge will build over
the northeast Caribbean during the period and then erode during
the weekend. East- northeast winds will promote near to below
normal temperatures as the somewhat cooler air mass behind the
front set over the islands. Additionally, breezy to locally strong
trade winds will promote moisture convergence over the region,
which may result in variable to showery weather on Wednesday.
Apart from showers affecting windward sectors, afternoon
convection should concentrate over the interior to the
southwestern quadrant of Puerto Rico during the period.

&&

.AVIATION...
(06Z TAFS)

VFR conds will prevail today across most of the terminals today.
SHRA/TSRA will likely develop ovr ctrl Mtn range of PR btwn 07/15-
23z with brief MVFR psbl w/SHRA-or isolated TSRA/Low clds,
especially near JPS/JSJ. SFC wnd lgt and vrbl thru 07/13z, then will
range btwn 5-15 kt from the SE-ESE with sea breeze variations and
higher gusts.


&&

.MARINE...

An approaching cold front from the northwest and a surface high
pressure anchored over the central Atlantic well northeast of the
region, will promote light east-southeast winds through the rest of
the weekend. An upper-level trough crossing the region along with
the frontal boundary meandering north of the islands, may cause
unsettled weather conditions mainly over portions of the local
Atlantic waters by Sunday into Monday. Expect north to northeast
fresh winds and choppy seas, as the remnants of the frontal boundary
sink southwards into the Caribbean from late Monday onwards. Fresh
to strong winds and another long-dominant period northerly swell
will promote hazardous seas by the middle of the week.

&&

.BEACH FORECAST...

There is a moderate risk of rip currents for the northern
coastline of Puerto Rico, from Rincon to Ceiba, as well as for
Culebra, western St. John and eastern St. Croix. Low risk of rip
currents for other areas. Moderate risk will throughout Tuesday
evening, when choppy seas and a long period northerly swell will
promote a high risk of rip currents across most of the local
beaches in PR and the U.S. Virgin Islands. The Caribbean Coastline
and south-facing beaches will have a low risk of rip currents
through at least Thursday.

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
503 AM AST Mon Apr 8 2024

.SYNOPSIS...

A cold front will linger north of the region and the associated
moisture will sink southward and promote a more showery weather
pattern through Tuesday with a prefrontal surface trough creating
favorable conditions for afternoon convection. Afternoon showers
and possible thunderstorms will form along the cordillera,
spreading into surrounding areas. However, this time, the
strongest afternoon activity may be observed across the southern
slopes of PR as winds slowly shift from the NE.

Although a limited heat risk is in effect today, as winds become
east- northeasterly and increase by Tuesday onwards, more pleasant
temperatures are forecast. Marine and coastal conditions will
deteriorate tomorrow onwards. By Friday and the upcoming weekend,
the remnants of the cold front will increase the chances for any
rainfall activity.

&&

.SHORT TERM...Today through Wednesday...

Calm weather conditions prevailed overnight, with another night with
low temperatures remaining warmer than usual, especially across
urban and coastal areas, regarding the mostly clear to partly cloudy
skies we observed. The Doppler Radar detected shower activity across
the local waters and some brushed PR's southeast coast, while the
radar detected little or no rain elsewhere. Winds were light and
variable overnight.

Once again, as the day begins warmer than usual with little or no
rain, above-normal heat indices, between 100 and 107 degrees
Fahrenheit, will likely return throughout the day due to the
combination of maximum temperatures in the low 90s and above-normal
moisture content (as last night's sounding reported as well as the
latest GOES-E-derived Precipitable Water).

The approaching remnants of the cold front and the induced
prefrontal surface trough will create favorable weather conditions
for today's observation of unsettled weather, especially this
afternoon and evening. Additionally, the departing short-wave trough
aloft will weaken the mid-level high. When combined with local
effects, the approaching front and prefrontal trough will allow
isolated to maybe scattered thunderstorms to form later today. The
factors mentioned above, with the weak steering winds, will favor
the formation of persistent rainfall activity over the mountains,
spreading into the surrounding areas, resulting in urban and small
stream flooding and possibly flash flooding. However, this time, the
strongest afternoon activity may be observed across the southern
slopes of PR as winds slowly shift from the NE. Rainfall amounts,
especially along the mountain areas and interior sections and near
isolated urban areas, may range between 1 and 2 inches, with
isolated higher amounts.

The pattern of near to above-normal moisture will extend through
Tuesday, as model guidance suggests. Also, winds will slowly
increase and shift from the north to northeast late this afternoon
into the evening, ending the warm trend we have observed since last
Thursday. Under this weather pattern, wet and unstable conditions
may extend into Tuesday, resulting in another round of 1.5
additional rainfall amounts, as the National Blend of Models
suggests. Eastern PR, including the SJ metropolitan area and the
U.S. Virgin Islands, may observe inclement weather late tonight into
early Tuesday morning. This activity may result in water ponding in
poorly drained areas and urban and small stream flooding, especially
across poorly drained areas.

There may be more moisture than usual on Wednesday; however, the
temperatures may be below normal. As the mid-level high pressure
builds aloft, there may be less potential for thunderstorms.
Nevertheless, the windward sections may experience some showery
weather due to moisture convergence under a breezy trade wind
pattern. We anticipate the moisture to gradually decrease by late
Wednesday, resulting in a return to the usual weather pattern by mid-
week.

.LONG TERM...Thursday through Monday...

No major changes to the long term forecast. A surface high pressure
will build into the Central Atlantic, north of the area, and
gradually spread eastward. This system will promote breezy to
locally strong east-northeast winds through the period, gradually
decreasing Sunday to Monday. To start the period, moisture related
to a past frontal boundary will be filtering away southwest of the
region, decreasing precipitable water (PWAT) values to normal and
then below normal. Model guidance suggest this drying pattern to
continue through early Friday morning, by this time remnants of
the past frontal boundary will filter in from the easy, steered by
east- northeast winds, possibly as a trade wind perturbation, and
increase moisture (to up to above normal PWAT), rain chances and
promote variable to showery weather Friday and Saturday. Model
guidance suggests only up to normal PWAT values through Monday
evening, when another patch of moisture reaches the islands. Model
guidance has backed off on the height of the available moisture,
now suggesting that most available moisture will stay below 700mb
through most of the period. This is due to a mid to upper level
ridge building over the northeast Caribbean during the period,
gradually eroding during the weekend. East- northeast winds will
promote near to below normal temperatures as a somewhat cooler air
mass sets over the islands. Apart from showers steered by breezy
to locally strong trade winds affecting windward sectors,
afternoon convection should concentrate over the interior to the
southwestern quadrant of Puerto Rico during the period.

&&

.AVIATION...
(06Z TAFS)

VFR conditions expected this morning. SHRA/isold TSRA ovr ctrl mtn
range, spreading to the rest of PR may create MVFR or even IFR
conds, especially btwn 08/15-23z. A second round of SHRA/TSRA may
affect JSJ/IST/ISX btwn 08/23-09/04z. Expect calm-light/VRB winds
thru this 08/13z, when sea breeze will kick off, increasing winds at
around 10 kts, but locally higher near SHRA/TSRA. N/NE winds will
slowly increase during the afternoon into Tuesday.

&&

.MARINE...

An approaching cold front from the northwest and a surface high
pressure anchored over the central Atlantic well northeast of the
region, will promote light east-southeast winds through today. An
upper-level trough crossing the region along with an induced surface
trough across forecast area, will increase the chance for showers
and possibly isolated thunderstorm development over portions of the
regional waters and passages until Tuesday. Expect moderate to fresh
north to northeast winds and choppy seas by late tonight, as the
remnants of the frontal boundary sink southwards into the Caribbean.
Fresh to locally strong winds and a long-dominant period northerly
swell will promote hazardous seas by midweek.

&&

.BEACH FORECAST...

There is a moderate risk of rip currents for the northern
coastline of Puerto Rico, from Rincon to Fajardo, as well as for
Culebra, northwestern St. Thomas and eastern St. Croix. Low risk
of rip currents for other areas. Moderate risk will last throughout
tomorrow evening, when choppy seas and a long period northerly
swell will promote a high risk of rip currents across most of the
local beaches in PR and the U.S. Virgin Islands through Sunday.