Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
353 AM AST Wed Mar 25 2026

...New SHORT TERM, LONG TERM, AVIATION, MARINE, BEACH FORECAST...

.KEY MESSAGES...
Issued at 349 AM AST Wed Mar 25 2026

* Unsettled weather across Puerto Rico today, with periods of
showers and isolated thunderstorms, particularly during the
afternoon hours, leading to localized ponding of water in
urban and low-lying areas.

* More unstable conditions expected from Thursday into Friday across
the islands, as a wetter and more dynamic pattern increases
the potential for widespread showers, thunderstorms, and
periods of moderate to heavy rainfall.

* Moderate risk of rip currents across northern and exposed
beaches, with hazardous marine conditions promoting life-
threatening currents in the surf zone.

* Variable weather conditions across the U.S. Virgin Islands,
with passing showers at times, but overall limited duration of
rainfall activity.

&&

.Short Term(Today through Friday)...
Issued at 349 AM AST Wed Mar 25 2026

A fairly active weather pattern was observed overnight, with
persistent showers from Luquillo westward into Morovis. Showers
were strong, especially around 12 AM across Corozal, Morovis,
Naranjito, and along Rio Grande and Canovanas. By 2 AM, showers
had diminished across the interior sections, but were still
spreading northward into Dorado, Toa Alta, Manati, and Vega Baja.
This increase in showers led to rises along small streams across
most of the affected municipalities. Several flood advisories and
warnings were in effect from late night into the early morning
hours. As of 3 AM, the bulk of the showers was affecting
municipalities from Manati eastward into the San Juan area.
Rainfall accumulations were significant across most of the
interior areas; radar estimates ranged from 2 to 5 inches, with
the highest amounts in Corozal, Morovis, and Naranjito, where
estimates reached 9 inches. Overnight temperatures were in the low
60s across the mountain areas, with some upper 50s due to the
persistent shower activity, while coastal areas remained in the
mid-70s.

For today, a similar weather pattern is expected, with a mid-
level closed low promoting instability and favorable conditions
for a convective pattern, leading to the development of strong
showers across the region. At the surface, winds will remain from
the east-southeast in response to a combination of a surface high
pressure extending from the Central Atlantic into the Caribbean
and an elongated surface trough. All that, and instability aloft
from a 250 MB +80 knots jet stream will result in another active
day. Therefore, residents and visitors can expect moderate to
strong showers in the northeastern sections in the morning,
followed by deep convection across the northwestern quadrant. With
the heaviest showers, urban flooding is expected along with rapid
rises in small streams across the interior and western PR.

On Thursday into Friday, the overall synoptic pattern is forecast
to transition to a more unstable and dynamically favorable regime
across Puerto Rico and the U.S. Virgin Islands, driven by a deep
upper-level trough interacting with a strengthening subtropical
jet. This interaction will result in a jet streak exceeding 100
knots across the region, enhancing upper-level divergence and
promoting large-scale ascent, which will in turn support a more
active convective pattern across the islands. Model guidance
indicates a notable cooling aloft, with 500 mb temperatures
decreasing to around -9 to -10 °C, contributing to increased
instability, while a deep layer of moisture will be present as
relative humidity values between 850 and 500 mb rise to levels
exceeding two standard deviations above climatological normals,
indicating an anomalously moist column. At the surface,
precipitable water values are expected to range between 1.75 and
1.90 inches, near the 75th percentile for this time of year,
providing sufficient moisture for widespread shower and
thunderstorm development. Overall, this combination of strong
upper-level forcing, increased instability, and abundant moisture
will support a wetter and more active weather pattern, with an
increased potential for periods of moderate to heavy rainfall,
particularly during the afternoon and evening hours, along with an
elevated risk of urban and small stream flooding in susceptible
areas.


&&

.Long Term(Saturday through Wednesday)...
Issued at 349 AM AST Wed Mar 25 2026

A mid- to upper-level low will move northeast of the northeastern
Caribbean between Saturday and Sunday. This feature will induce
trade wind perturbations that will periodically move across Puerto
Rico and the U.S. Virgin Islands, promoting passing showers,
particularly across windward areas. Expect a variable pattern
through the weekend, with a mix of sunshine and brief periods of
showery weather, mainly during the overnight and morning hours as
these disturbances advect across the region. During the afternoon
hours, local effects and sea breeze convergence will support
isolated to scattered convection, mainly across the interior and
southwestern Puerto Rico.

From Monday through midweek, a mid- to upper-level trough
interacting with an approaching frontal boundary will promote a more
unsettled, wetter pattern across Puerto Rico and the U.S. Virgin
Islands. Increasing moisture and instability will support a higher
coverage of showers and thunderstorms. Breezy to locally windy
conditions are also possible as winds strengthen behind the frontal
boundary.

Coastal conditions will deteriorate during this period. A long-
period northerly swell arriving late Monday night could produce
dangerous breaking waves and hazardous coastal conditions through at
least midweek, peaking around Tuesday.

The potential impacts for the first part of the holiday week include
urban and small-stream flooding, a limited risk of flash flooding,
isolated thunderstorms with lightning, breezy to windy conditions,
life-threatening rip currents, high surf, and possible coastal
flooding along vulnerable north- and west-facing coastlines.

&&

.AVIATION...
(06Z TAFS)
Issued at 349 AM AST Wed Mar 25 2026

Mainly VFR conditions are expected across all terminals; however,
VCSH and SHRA will persist along TJSJ until 25/15Z. Brief MVFR to
IFR conditions are anticipated across TJSJ and TJBQ from 25/16Z
to 25/21Z due to passing SHRA, with lower CIGS and reduced
VIS possible. Shower activity developing across the interior and
western mountains will result in cloud coverage affecting FL020 to
FL060. Winds will remain generally from the E to ENE at around
10–15 knots, with higher gusts near shower activity.

&&

.MARINE...
Issued at 349 AM AST Wed Mar 25 2026

A weak surface high pressure over the southwestern Atlantic will
merge with a stronger high pressure over the north central Atlantic
by the end of the workweek. This will promote light to moderate
trades for the next several days. Seas will remain at 5 feet or less
through the weekend. Late in the weekend and into early next week, a
large swell is forecast to build seas up to 10 feet across the
Atlantic waters and passages. Also, winds will increase around 20
knots due to an approaching front and stronger surface high pressure
developing over the western Atlantic.

&&

.BEACH FORECAST...
Issued at 349 AM AST Wed Mar 25 2026

A moderate risk of rip currents is expected to prevail through the
weekend across the north and east facing beaches of Puerto Rico, and
across the U.S. Virgin Islands. A moderate risk means that life-
threatening rip currents are possible in the surf zone, as rip
currents can still occur near groins, jetties, reefs, and piers. By
early next week, a large northerly swell and increasing winds will
cause large breaking waves that can lead to high surf conditions and
minor coastal flooding along the Atlantic coastlines of the
islands.

[TomballEd]

Saw 100 knot jet streak mentioned. Here in Texas that might suggest severe weather, even hail. I imagine hail is infrequent that far south but does it happen at all?