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576
FXCA62 TJSJ 201757
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
157 PM AST Tue Jan 20 2026

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

.KEY MESSAGES...
Issued at 138 PM AST Tue Jan 20 2026

* Choppy to rough seas will continue to result in hazardous marine
  and coastal conditions. Small craft operators and beachgoers
  should continue to exercise caution, as Small Craft Advisories and
  High Rip Current Statements remain in effect through most of the
  workweek.

* Trade wind-driven showers will persist, moving from time to time
  and producing slippery road conditions and ponding of water in low-
  lying and poor drainage areas through this evening.

* A surface trough moving westward across the region from Wednesday
  into Friday will lead to a gradual deterioration in weather
  conditions, increasing the potential for showers and isolated
  thunderstorms.

* Breezy to windy conditions will continue, particularly on
  Wednesday, which could cause outdoor items to be blown around or
  damaged.

&&

.Short Term(This evening through Thursday)...
Issued at 138 PM AST Tue Jan 20 2026

Fast-moving showers move across the local waters and into the
islands during the morning hours, particularly over portions of the
U.S. Virgin Islands and eastern Puerto Rico. Based on WSR-88D
rainfall estimates, accumulations remain minimal, between 0.20 AND
0.30 inches, over the aforementioned areas. Breezy to windy
conditions persisted as well, with CWOP/HADS/ASOS stations
reporting wind gusts between 25 and 30 mph across coastal areas
and higher elevations, with the highest (35 mph) at the Cyril E.
King International Airport at St. Thomas and the Henry Rohlsen
International Airport in St. Croix in the U.S. Virgin Islands
early today. For the rest of the afternoon, isolated to scattered
showers are expected to move across the islands, bringing brief
periods of heavy rainfall and gusty winds, and resulting in
localized ponding of water over roadways and poorly drained areas.

This evening, conditions will briefly improve due to a drier air
mass (PWAT around 1.20 inches) filtering into the region,  reducing
the frequency of showers. Nevertheless, moisture content will
increase once again late tonight and early tomorrow, with showers
embedded in the trades moving over the local waters and passages
into windward sections. Nevertheless, accumulations should remain
minimal. This weather pattern is expected to continue throughout the
day, with shallow afternoon convection over western portions of
Puerto Rico.

Weather conditions will become wetter and marginally unstable as a
cut-off low across the Central Atlantic induces a surface trough,
expected to approach the CWA by late Wednesday night into
Thursday. From the latest model guidance, ensemble members suggest
PWAT values are likely to increase, with a medium to high chance
of exceeding climatological normal values (> 1.50 inches) for this
time of the year. In terms of deep convection, with the presence
of the upper-level low, mid- level temperatures are expected to
cool (500 mb temperatures around -7 degrees Celsius), and a jet
streak should increase wind speed aloft, with 250 mb winds around
60 kt, allowing cloud growth and ventilation. Hence, the most
likely scenario should mostly be an advective pattern throughout
the day, with scattered showers and isolated thunderstorms moving
across the local waters and passages into the U.S. Virgin Islands
and half east of Puerto Rico. Additionally, afternoon convection
is likely over western portions of Puerto Rico as well. Although
winds will likely weaken, showers and isolated thunderstorms
should bring periods of heavy rainfall and gusty winds, resulting
in ponding of water over roadways, urban, and poorly drained
areas, with minor flooding over the aforementioned areas.
Additionally, reduced visibility and lightning cannot be ruled
out. Hence, the flooding and lightning risk will remain limited.

The broad surface high pressure over the Central Atlantic continues
to strengthen, promoting breezy to windy conditions across the
Caribbean Basin. These conditions are likely to deteriorate
tomorrow, with winds likely between 25 and 30 mph and gusts up to 35
mph, affecting the U.S. Virgin Islands and exposed coastal areas of
Puerto Rico. Residents and visitors are encouraged to secure loose
items that may blow around and report wind-related damage, if any.

&&

.Long Term(Friday through next Monday)...
Issued at 507 AM AST Tue Jan 20 2026

Some changes were introduced to the long-term forecast. For
Friday, surface conditions will remain unsettled as a surface
disturbance moves across the area, inducing instability and plenty
of moisture. Therefore, the forecast calls for a pattern with an
increase in the frequency of isolated to scattered showers,
especially in the morning and evening hours across eastern
sections of Puerto Rico, followed by afternoon showers along the
western interior. Model guidance suggests precipitable water
values fluctuating between 1.6 and 1.9 inches, slightly above
climatological normals. When combined with colder temperatures at
500 mb, these conditions may support the development of one or two
isolated thunderstorms with the strongest shower activity.
Although showers might result in some hazardous conditions, no
rainfall threat is forecast due to the breezy conditions resulting
in fast-moving showers across the area. Some moisture will remain
across the area from early Saturday and spread during the day;
therefore, in contrast to yesterday, Saturday looks more showery
with isolated to scattered showers.

Weather conditions will improve by late Saturday into Sunday as
the disturbance moves out of the region and a drier air mass
filters into the local islands. At the surface, a broad high-
pressure system extending across the Atlantic basin will promote
mostly easterly winds across the area. At the mid to upper levels,
subsidence will inhibit widespread shower development; however,
local effects may still support brief isolated to moderate
showers, with no flooding threat expected each day. On late Monday
into Tuesday, surface conditions will change as winds begin to
veer in response to a pre-frontal trough moving southward near
northern Hispaniola. Winds will turn more northeasterly, resulting
in a more advective pattern and slightly cooler temperatures,
particularly during the morning and nighttime hours.

&&

.AVIATION...
(18Z TAFS)
Issued at 138 PM AST Tue Jan 20 2026

VFR conds should persist across all terminals during the TAF prd,
with mainly VCSH with -SHRA for JSJ and JPS due to passing SHRA that
may reduce CIGs/VIS through 20/22z. Gsty winds from the E will
continue this aftn, btwn 25 and 30 kt, weakening by 20/22-23z except
for IST and ISX, which can expect gusts up to 22 kt during the
night. By 21/12-13z, winds will strengthen and become higher across
TAF sites, with winds btwn 20 - 22 kt and gusts btwn 30 - 32 kt.
VCSH expcd at eastern TAF sites aft 21/12-13z.

&&

.MARINE...
Issued at 138 PM AST Tue Jan 20 2026

Broad surface high pressure over the central Atlantic will
continue to influence the regional waters through the workweek.
Fresh to locally strong east winds will persist, maintaining
choppy to rough seas. Small Craft Advisories remain in effect at
least through late Wednesday night, as hazardous marine conditions
will continue for most of the regional waters. Mariners should
continue to exercise caution until seas and winds further
diminish.

&&

.BEACH FORECAST...
Issued at 138 PM AST Tue Jan 20 2026

A High Rip Current Statement remains in effect for the north- and
east-facing beaches of Puerto Rico, including Culebra, as well as
the U.S. Virgin Islands. Residents and visitors are urged to
continue following the beach warning flag system and to favor
beaches with a lower risk of rip currents, such as those along the
western and southern coasts of Puerto Rico.

In addition, breezy to locally windy conditions continue along
coastal areas, which may still result in unsecured objects being
blown around, particularly in the most exposed locations. Beachgoers
should remain cautious both in and near the water until conditions
improve further.

For localized and updated risk levels, visit weather.gov/beach/sju.

&&

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

VI...High Rip Current Risk through late tonight for VIZ001-002.

AM...Small Craft Advisory until midnight AST Wednesday night for
     AMZ711-712-716-723-726-733.

     Small Craft Advisory from 6 PM this evening to midnight AST
     Wednesday night for AMZ741.

&&

$$
SHORT TERM/AVIATION...MNG
LONG TERM...LIS
MARINE/BEACH FORECAST...CVB

NWS SJU Office Area Forecast Discussion