National Weather Service San Juan PR
532 AM AST Fri Feb 9 2024
.SYNOPSIS...
Issued at 522 AM AST Fri Feb 9 2024
Stable weather conditions will persist during the next several
days as a broad high pressure dominates across the Atlantic and a
drier airmass is establishing over Puerto Rico and the U.S. Virgin
Islands. Isolated shower activity cannot be ruled out of the
forecast due to shallow moisture and light winds, mainly during
the morning hours over the eastern PR. A warming trend is
anticipated from Tuesday onwards as winds will shift from the
southeast and moisture will increase from the south. Northerly
swells arriving over the next several days will further
deteriorate marine and coastal conditions for the Atlantic waters
and local passages through early next week.
&&
.SHORT TERM...Today through Sunday
Variable weather conditions prevailed during the night hours, with
isolated to moderate showers affecting northern and interior
sections of Puerto Rico as well as the local waters. Shower activity
was frequent. However, rainfall accumulations remained minimal;
according to the Radar Doppler estimates, the highest occurred
across Manati and Naguabo, with almost 3/4 of an inch. Overnight
temperatures ranged from the low to mid-70s along the coastal areas
and in the low to mid-60s across the mountain sections.
Today, a variable weather pattern is expected as a pocket of
cloudiness and shallow moisture stream across the northern coastal
areas. The shower activity will be shallow, and no significant
rainfall accumulations anticipated for the rest of the morning,
but ponding of water in low-lying areas and urban sections cannot
be ruled out. As the day progresses, a much drier airmass with
Precipitable water around 0.80 inches (GOES Satellite-derived
Imagery) will move into the region, leading to a more stable
weather pattern with some clouds and localized showers in the
afternoon across the interior and southern areas due to the wind
direction.
By Saturday into Sunday, a broad mid- to upper-level ridge across
the western Atlantic extending into the Caribbean will be the
dominant feature, resulting in a strong trade wind cap with warmer
temperatures at 500 MB and drier air aloft. A similar pattern will
be reflected at the surface, with the influence of a broad surface
high-pressure extending from the Western Atlantic into the central
Atlantic. This surface feature will induce a variation in wind
direction, persisting from the northeast early on Saturday and
veering on Sunday, becoming more easterly. According to the model
guidance, precipitable water values will drop two standard
deviations from the normal climatological values on Saturday and
slightly increase on Sunday. Given the expected weather, the islands
can expect shower activity resulting from local and diurnal effects
and available moisture. Although showers are expected, widespread
shower activity is not anticipated.
&&
.LONG TERM...Monday through Friday...
Weather models agree that a broad surface high pressure centered
over the Atlantic will continue to dominate weather conditions in
our region for the beginning of this work week. At the mid-levels,
a similar pattern is expected, with models suggesting a broad
mid-level ridge extending from the western Atlantic to the
Caribbean. As a result, winds will remain relatively light from
the northeast promoting temperatures to remain near normal to
slightly below normal on Monday across Puerto Rico and the U.S.
Virgin Islands. It is forecast that the precipitable water content
in the atmosphere will remain around 1 inch, which is below
normal, however, some isolated shower activity cannot be ruled out
from the forecast due to shallow humidity and light winds, mainly
during the morning hours over eastern PR, but under this pattern
the rain should be very limited.
At the same time, a low pressure along with its associated cold
front will be moving over the Southeastern U.S. towards the
western Atlantic which will weaken and push the high pressure over
the Atlantic towards the east. That pattern will change our wind
flow from the southeast. Therefore, from Tuesday onwards we are
anticipating a warming trend in temperatures and an increase in
tropical humidity across the forecast area. Expect temperatures to
be around 3 to 5 degrees above normal for this time of the year
and PWAT values could be ranging closer to normal; ~1.5 inches. As
a result, around Tuesday afternoon into Wednesday, we can expect
the return of a more variable weather pattern with isolated to
scattered showers gradually developing throughout the day.
By the latter part of the week, the weakening cold front will be
located well north of our region, and patches of drier air will
settle over our region. It will continue to be warmer-than-normal,
and diurnal/local effects will promote a pattern of passing rain
showers across eastern Puerto Rico and the U.S. Virgin Islands,
followed by afternoon convection primarily across the interior to
the western section of Puerto Rico with the easterly wind flow. We
will continue to monitor closely for any changes.
&&
.AVIATION...
(12Z TAFS)
Issued at 522 AM AST Fri Feb 9 2024
VFR conditions will prevail across all the TAF sites as a much
drier airmass moves into the region, limiting cloudiness and
showers. But until 09/15Z, VCSH to -RA will persist across TJSJ
and TJPS. Winds will continue from the N, increasing to 15 knots
at 09/15Z, with gusty winds and sea breeze variations. Winds will
turn more from the N-NE at 10/03Z.
&&
.MARINE...
Issued at 522 AM AST Fri Feb 9 2024
Moderate to fresh northerly wind flow will be present across the
local waters as a broad surface high pressure dominates across the
western Atlantic. Winds continue to gradually veer over the next
few days until becoming easterly by the weekend. Pulses of
northerly swells will spread across the local waters into the
weekend, creating hazardous marine and coastal conditions for the
Atlantic waters and local passages through early next week.
Therefore, Small Craft Advisories will remain in effect due to
seas building between 7 and 10 feet during the next few days.
Please refer to the latest Marine Weather Message (MWWSJU) for
additional details.
&&
.BEACH FORECAST...
Issued at 522 AM AST Fri Feb 9 2024
Pulses of long period swells will cause large breaking wave action
across west, north, and eastern beaches of Puerto Rico, Culebra,
and the northern U.S. Virgin Islands through at least early next
week. Therefore, a High Rip Current Risk and a High Surf Advisory
are in effect due to dangerous large breaking waves and life-
threatening rip currents. Please refer to the latest Coastal
Hazard Message and Surf Zone Forecast (SRFSJU) for detailed
information (CFWSJU). A larger northerly swell with longer wave
periods is expected on Sunday and Monday.