920
FXCA62 TJSJ 150729
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
329 AM AST Wed Apr 15 2026

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

.KEY MESSAGES...
Updated at 327 AM AST Wed Apr 15 2026

 * A high risk of rip currents will persist along the northern coast
   of Puerto Rico due to ongoing northerly swell activity,
   resulting in hazardous marine and coastal conditions.

 * Variable weather conditions are expected today, characterized
   by periods of sunshine and passing morning showers, followed by
   the development of afternoon convection across portions of the
   islands driven by local and diurnal effects.

 * Increasing instability from Thursday into Friday, associated
   with an amplifying upper-level trough and enhanced moisture
   availability, will promote a more active weather pattern with widespread
   afternoon convective development across Puerto Rico.

 * Southeasterly low-level winds will promote slightly above-
   normal temperatures, particularly across coastal and urban
   areas.

&&

.Short Term(Today through Friday)...
Issued at 327 AM AST Wed Apr 15 2026

A relatively tranquil weather pattern prevailed during the
overnight hours, with mostly clear skies as earlier upper-level
cloudiness and showers shifted eastward and remained over the
surrounding waters or moved out of the forecast area. As a result,
the islands experienced clear to partly cloudy conditions. Some
showers and isolated thunderstorms lingered across the
southeastern quadrant of the CWA, mainly affecting the Caribbean
waters, with the strongest activity observed around midnight.
Overnight temperatures ranged from the low to mid 70s across
coastal areas, with slightly cooler and more refreshing conditions
across the higher elevations. Winds remained light and variable
at around 5 mph or less.

An unstable and moist weather pattern is expected today across
Puerto Rico and the U.S. Virgin Islands. Atmospheric conditions
will support the development of showers and a few thunderstorms,
aided by abundant low-level moisture and the presence of a surface
trough across the region. In addition, a cut-off low aloft is
enhancing upper-level westerly winds (zonal flow), which may help
some storms become more organized and produce locally strong wind
gusts. At the low to mid levels (1000700 mb), winds will range
from the southeast to the south due to the surface trough, with
its axis over Hispaniola, and a mid-level low positioned just west
of the forecast area. This wind pattern is favorable for the
development of showers across northeastern Puerto Rico, extending
into north-central areas. Given the mostly clear conditions early
in the day, local and diurnal effects are expected to develop
early, potentially leading to convection by mid-morning across
northeastern Puerto Rico, including areas near El Yunque. Showers
will mainly affect northeastern areas during the morning,
followed by activity developing over the northwestern portions and
drifting into northwestern to north-central areas, as suggested
by high-resolution models. Therefore, there is a moderate to high
confidence that the bulk of the showers will be between 12 PM to 6
PM across northwestern sections, where the heaviest showers can
result in flooding problems in urban areas especially.

For late tonight into Thursday, conditions will become slightly
more favorable for instability as an upper-level trough amplifies
just west of the region, placing the divergent side of the system
over much of the eastern portion of the CWA. This setup will
enhance upper-level diffluence and support increased upward
motion, leading to a more favorable environment for convective
development. This pattern is expected to persist through the rest
of the period, as another cut-off low establishes over Hispaniola
and stalls, maintaining a diffluent pattern across the area.
Considering this overall setup, a wetter pattern is likely from
Thursday into Friday. Global model guidance and high-resolution
models suggest active afternoons driven by local and diurnal
effects, supported by limited early cloud cover. For Thursday, an
increase in low-level winds is forecast, as indicated by 925 mb
wind speeds, resulting in faster-moving showers that may limit
rainfall accumulations. Additionally, precipitable water values
are expected to remain around the 75th percentile on both days,
supporting periods of rainfall.

&&

.Long Term(Saturday through Wednesday)...
Issued at 327 AM AST Wed Apr 15 2026

Variable conditions may persist through the weekend, with a gradual
improvement over the first part of the next workweek. Wind pattern
will mostly be dominated by a surface high pressure lingering over
the Central Atlantic, promoting winds from the E-SE. Another feature
that may influence the weather pattern in the deep-layered trough
that, according to the latest model guidance, is expected to linger
over Hispaniola. From the deterministic guidance of the GFS and
ECMWF, it seems that Saturday and Sunday will most likely be the
wettest days of the period, with PWAT values lingering between 1.8
and 2.0 inches, wet for this time of the year. Additionally, low to
mid level moisture content will remain high (above 60%), while model
sounding suggests skinny profiles. Conditions look favorable for
convection, as the influence of the trough will maintain slightly
cooler than normal mid level temperatures (around -8 degrees
Celsius) and a nearby jet with strong winds aloft (around 60 knots),
allowing cloud growth and ventilation. With the favorable side of
the trough over the CWA, divergence aloft will also increase the
chance of deeper convection, particularly over western Puerto Rico
and the U.S. Virgin Islands. Hence, for the U.S. Virgin Islands,
showers and isolated thunderstorms will likely move occasionally
throughout the day, while interior and western Puerto Rico can
expect showers and thunderstorms in the afternoon that may persist
into the evening. Due to previous rainfall activity, soil
saturation, and high river levels, the potential for flooding may
increase. Hence, the flooding threat will remain limited to elevated
for the aforementioned areas. Besides flooding, expect gusty winds
and lightning across these areas. For the rest of the areas, passing
showers may move from time to time, though a significant flooding
threat is not expected. Weather conditions will gradually improve
Monday onwards, as moisture content may decrease and the subsident
side of the trough moves over the CWA. Nevertheless, theres
uncertainty between global solutions as GFS continues with a wet
pattern (above normal PWAT) while the ECMWF on the side is moving
toward a more seasonal to drier pattern. From the latest grand
ensemble, theres variability between them (PWAT difference of half
an inch), particularly in the mid to high level moisture content. At
the moment, expect a seasonal weather pattern, with isolated showers
moving over windward sections in the morning hours, with afternoon
convection over interior and western Puerto Rico. Due to the
uncertainty, the flood threat will remain limited.

&&

.AVIATION...
(06Z TAFS)
Issued at 327 AM AST Wed Apr 15 2026

SHRA with VCTS will persist near TISX, while VFR conditions
prevail across the remaining TAF sites during the morning hours.
Winds will remain light and variable at less than 5 kt, increasing
around 15/15Z from the S-SE at 1015 kt. SHRA and isolated TSRA
are expected to impact TJBQ and TJSJ from 15/18Z onward, resulting
in reduced CIGS and VIS, with ceilings lowering to FL020FL050.

&&

.MARINE...
Issued at 327 AM AST Wed Apr 15 2026

A surface high pressure system over the eastern to central Atlantic,
interacting with a stationary frontal boundary north of the region,
will promote light to gentle winds tonight. Pulses of northerly
swell spreading across the Atlantic waters will continue to maintain
seas up to 6 feet across exposed areas, where small craft should
exercise caution over the next several days. Showers and strong
thunderstorms will continue across the local waters due to the
presence of a frontal system and a trough, creating locally
hazardous marine conditions through this afternoon. Winds are
expected to become gentle to moderate from the east to east-
southeast today through the weekend.

&&

.BEACH FORECAST...
Issued at 327 AM AST Wed Apr 15 2026

A High Rip Current Risk is in effect for the northern exposed
beaches of Puerto Rico and Culebra through this afternoon due to the
arrival of pulses of a weak northerly swell. Beachgoers are urged to
heed the advice of lifeguards, as well as beach patrol flags and
posted signs. Elsewhere, a low to moderate risk of rip currents will
persists. Increasing winds from midweek onward could lead to a
moderate risk of rip currents persisting along north-exposed beaches
through at least next Saturday. Residents and visitors are
encouraged to exercise caution, especially along exposed coasts. For
more specific area details, refer to weather.gov/beach/sju.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk through this afternoon for PRZ001-002-005-
     008-010-012.

VI...None.
AM...None.
&&

$$

SHORT TERM...LIS
LONG TERM....ICP
AVIATION...LIS

NWS SJU Office Area Forecast Discussion