607
FXCA62 TJSJ 040914
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
514 AM AST Fri Apr 4 2025

.SYNOPSIS...

Windy conditions will continue today, with sustained winds
between 20 to 25 mph and wind gusts over 40 mph. A variable
weather pattern is forecast for the next workweek, with fair
weather conditions and occasional trade wind showers moving over
the windward areas during the first part of the week, and
increasing moisture content during the second part. Marine and
coastal conditions remain hazardous for small craft and beachgoers
through the weekend.


&&

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

A surface high pressure spread from the Western to the Central
Atlantic will sink southwards today, further tightening the local
pressure gradient. This will promote windy conditions today across
the islands, and a Wind Advisory remains in effect through at
least 8 PM tonight. Sustained winds of 20 to 25 mph, with
frequent gusts ranging from 35 to 45 mph are expected, and mainly
across the lower elevations. A drier air mass will move over the
region today, promoting fair weather and increasing the potential
for fire weather conditions. However, showers embedded in the
trade winds are expected to move over portions of eastern and
northern PR, as well as across the northern USVI tonight.

A TUTT-low northeast of the region will continue to promote colder
than normal 500 mb temperatures (-9/10C), increasing instability
which could promote the formation of isolated thunderstorms on
Saturday afternoon over western PR. However, the limiting factor
is the dry air mass at mid-levels, which could promote subsidence
aloft and less potential for widespread activity. Another drier
air mass is expected on Sunday, and the precipitable water content
is forecast to drop under 1 inch, well below normal values.

Life-threatening rip currents are expected to form daily at local
beaches. Residents and visitors are strongly urged to follow the
guidance of lifeguards and beach patrols. As a result, a high rip
current risk is in effect for the east and north-facing beaches of
Puerto Rico and the U.S. Virgin Islands, with occasional rip
currents also possible along the south and west coasts.

&&


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

The long-term forecast remains on track, with a variable weather
pattern ahead. The latest model guidance insists on another surface
high pressure building in the western Atlantic, promoting E-NE
winds. However, as the high pressure migrates eastward, the wind
pattern will remain from the E-SE. The first part of the workweek
will be dominated by a combination of drier air mass and patches of
moisture moving in occasionally. A mid to upper-level trough will
linger over the CWA, allowing ventilation and enhancing instability
aloft. Additionally, the 500 mb temperatures should remain between -
8 to -10 Celsius, promoting deep convection activity. However, the
limitations of moisture content may inhibit the shower and
thunderstorm activity. Expect isolated showers moving along windward
sections in the morning and over the interior to northwestern Puerto
Rico. Model guidance continues suggesting the transition to a wetter
pattern for the second part of the week. A frontal boundary and its
pre-frontal trough will approach the region by Wednesday, but the
best moisture content is expected to remain north of the local
islands. An induced low should move by the end of the workweek, with
above-normal Precipitable Water (PWAT) values ( 1.7 - 1.8 inches).
Enough moisture content could produce moderate to strong showers
across the region and increase flooding potential. Ponding of water
in roadways, urban, and poorly drained areas is very likely, along
with isolated urban and small streams flooding.

With a southeasterly flow dominating, temperatures could increase
and reach near above normal. However, this does not present a risk
of extreme heat for the CWA.

&&

.AVIATION...

(06Z TAFs)

Mainly VFR conditions are expected to prevail across all terminals
during the next 24 hours. However, trade wind SHRA en route just
east of Anegada will reach portions of the USVI and the east/northern
PR terminals later tonight. E-ENE winds at 20-25 knots, with
gusts up to 45 kt will continue through at least this evening.
Therefore, a Wind Advisory remains in effect for all PR and the
USVI.


&&

.MARINE...

A broad surface high pressure over the western Atlantic will continue
to promote fresh to locally strong east to east-northeast winds
through at least late tonight, then conditions will gradually
improve Saturday into Sunday. Rough seas will continue to build
between 6 and 9 feet, and occasionally higher, across most waters
resulting in hazardous seas through the weekend.


&&

.BEACH FORECAST...

Strong winds continue producing hazardous coastal conditions for
beachgoers. The High Rip Current Risk remains in effect through
Saturday afternoon for the northern beaches of Puerto Rico, from
Aguadilla to Fajardo, Culebra, St. Thomas, St. John, and St.
Croix. Additionally, the high risk of rip currents is now in
effect for the southeastern beaches of Puerto Rico, from Salinas
to Yabucoa, and Vieques through late tonight. The risk remains
moderate elsewhere.

Swimmers are urged to exercise caution by staying near lifeguards
or even better to stay out of the water. Rip Currents can sweep
even the best swimmers away from shore into deeper water, where it
becomes difficult to return to safety. Heed the advice of lifeguards,
beach patrol flags and signs.


&&

.FIRE WEATHER...

Strong winds up to 25 mph with gusts near 40 mph are expected to
continue today across Puerto Rico. In addition, a drier air mass
is expected to filter over the islands during the day, and the
relative humidity could drop between 35-45% across portions of
southern and western Puerto Rico early this afternoon. Given the
combination of the expected low relative humidities, dry fuels,
windy and gusty conditions, the potential for rapid fire spread is
elevated. The Fire Danger Statement issued emphasize the
heightened risk and urges extra precaution, particularly for
activities that could spark a fire, such as outdoor burning,
camping, or vehicle use in grassy areas.


&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk through Saturday afternoon for PRZ001-002-
     005-008-012.

     Wind Advisory until 8 PM AST this evening for PRZ001>013.

     High Rip Current Risk through late tonight for PRZ003-013.

VI...High Rip Current Risk through Saturday afternoon for VIZ001-002.

     Wind Advisory until 8 PM AST this evening for VIZ001-002.

AM...Small Craft Advisory until noon AST Saturday for AMZ711-712-716-
     723-726-733-741.

     Small Craft Advisory until 6 PM AST this evening for AMZ735-742.

     Small Craft Advisory until 6 AM AST early this morning for
     AMZ745.

&&

$$

DSR/MNG