272
FXCA62 TJSJ 161855
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
255 PM AST Fri Jan 16 2026

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

.KEY MESSAGES...
Issued at 244 PM AST Fri Jan 16 2026

* Deteriorating marine and coastal conditions are expected this
  weekend as a northerly swell combines with breezy winds, leading
  to hazardous seas and an increased risk of rip currents,
  especially along northern and northeast-facing beaches.

* A strengthening to moderate to locally breezy wind flow is
  forecast by this afternoon and will persist through the weekend.
  Secure loose outdoor objects and use caution in gusty wind
  conditions.

* Trade wind showers will continue, with a brief increase in
  rainfall activity possible during the afternoon hours, mainly
  across western Puerto Rico, resulting in wet roads and ponding in
  low-lying and poor drainage areas.

&&

.Short Term(This evening through Sunday)...
Issued at 244 PM AST Fri Jan 16 2026

Mostly fair conditions persisted across the islands, with a few
passing showers moving over portions of southeastern Puerto Rico.
Winds continue to increase across the local area, with stations
reporting maximum wind gusts between 24 and 29 mph over coastal
areas and higher elevations. The forecast for today remains on
track, with the highest chance of showers and isolated thunderstorms
in the afternoon. According to the 12z RAOB, the moisture content
remains high for this time of year, with PWAT values (1.58 inches)
exceeding the 75th percentile (1.49 inches). Although the sounding
reported 500 mb temperatures warmer than usual (around -3 degrees
Celsius), the proximity of a deep-layered trough over the
Hispaniola, diurnal heating combined with local effects, and sea
breeze convergence could be enough for breaking the inversion cap
and increasing the potential of thunderstorm activity. Hence,
isolated thunderstorms cannot be ruled out. This activity should
concentrate on portions of western Puerto Rico, and the most likely
scenario remains as ponding of water over roadways, urban, and
poorly drained areas, along with isolated minor flooding.

Variable and breezy conditions will persist in the short-term
forecast. The surface high pressure over the Central Atlantic will
strengthen, increasing the pressure gradient, and bringing breezy to
windy conditions across the islands. Hence, coastal areas and higher
elevations can expect higher wind gusts this weekend (between 26 and
38 mph). Current satellite-derived products show an area of drier
air mass (PWAT between 0.7 and 1.0 inches) over the Leeward Islands,
expected to filter into the region later tonight and limit shower
activity. Nevertheless, the frequency of showers is expected to
increase in the morning hours due to a patch of moisture moving
across the CWA. Based on HIRES models, passing showers are expected
to move across the U.S. Virgin Islands and eastern portions of
Puerto Rico, with afternoon convection still likely over portions of
western Puerto Rico. Nevertheless, rainfall accumulations in the
afternoon will at most lead to ponding of water over roadways,
urban, and poorly drained areas. In terms of lightning, the mid-
level ridge should strengthen once again and linger north of the
region, maintaining warmer than normal mid-level temperatures
(around -4 degrees Celsius) and increasing stability aloft. Hence,
the lightning risk will remain low. This weather pattern should
prevail on Sunday as well.

&&

.Long Term(Monday through next Thursday)...
Issued at 352 AM AST Fri Jan 16 2026

The latest model guidance indicates a transition toward a wetter
and more unsettled pattern beginning Monday and continuing through
much of the workweek. Precipitable water values are forecast to
increase to around 1.75 inches, which is above normal for this
time of year and supportive of additional rainfall activity,
particularly by midweek. From Monday through Wednesday, a
subtropical jet streak near 250 mb will enhance upper-level
divergence and support the development of an induced surface
trough, resulting in higher shower coverage across the forecast
area as easterly to northeasterly low-level flow becomes
established by midweek.

Tuesday may see some variability as guidance hints at a pocket of
drier air moving south of the region. At this time, it remains
unclear whether this drier air will reach the forecast area, and
its potential influence on rainfall will continue to be monitored.

Wednesday currently appears to be the wettest and most unstable day of
the long-term period. 500 mb temperatures near -7 degrees Celsius
will promote greater vertical growth of convection, increasing
instability and the potential for isolated thunderstorms,
particularly during the afternoon hours. In addition, weakening
low-level winds may allow showers to persist over the same areas
for extended periods, potentially elevating the risk of localized
flooding.

From Monday onward, 925 mb temperatures are expected to remain
above normal. When combined with the increasing moisture,
conditions may feel warmer than they actually are. While rainfall
coverage and intensity may vary at times, each afternoon carries
at least a limited flooding risk, primarily due to ponding of
water on roads and in poorly drained locations.

&&

.AVIATION...
(18Z TAFS)
Issued at 244 PM AST Fri Jan 16 2026

Mainly VFR conds are expcd across all TAF sites. Aftn cnvtn across
mountain ranges of PR will bring VCSH across all terminals through
16/22z, temporarily reducing CIGs. TSRA cannot be ruled, and AMDs
may be required for JPS and JBQ. A patch of moisture will increase
SHRA activity by 17/12z with passing showers across the TAF sites,
reducing once again CIGs and VIS. Winds from the E will slightly
weakened, btwn 8 - 10 kt, strengthening by 17/12-14z around 15 kt
and gusts up to 30 kt.

&&

.MARINE...
Issued at 244 PM AST Fri Jan 16 2026

Surface high pressure across the central Atlantic will continue to
support gentle to moderate east to southeast winds tonight. By
Saturday, model guidance continues to indicate strengthening east to
northeast winds along with the arrival of a long-period northerly
swell. This combination will result in building seas and
increasingly choppy to rough marine conditions, leading to hazardous
marine conditions across the regional waters from Saturday through
the remainder of the weekend.

&&

.BEACH FORECAST...
Issued at 244 PM AST Fri Jan 16 2026

The moderate risk of rip currents along all the northern-exposed
beaches of Puerto Rico and the U.S. Virgin Islands will remain
favorable through at least tonight. However, conditions are expected
to deteriorate beginning Saturday and persist through the weekend.

Model guidance continues to suggest a northerly swell moving into
the local waters, combining with rough seas generated by breezy
conditions. This pattern will lead to increasingly large breaking
waves and stronger nearshore currents, particularly along the north
and northeast-facing beaches of Puerto Rico, including Culebra, as
well as exposed beaches across the U.S. Virgin Islands.

As a result, a high risk of rip currents is expected to develop on
Saturday and continue through the weekend, posing hazardous
conditions for swimmers and beachgoers. Beachgoers are urged to
exercise caution, follow guidance from local authorities, and avoid
entering the water in areas under a high rip current risk.

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

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
AM...Small Craft Advisory from 2 PM Saturday to 2 PM AST Monday for
     AMZ711.

&&

$$

SHORT TERM/AVIATION...MNG
MARINE/BEACH FORECAST...CVB
LONG TERM...MMC

NWS SJU Office Area Forecast Discussion