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923
FXCA62 TJSJ 171829
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
229 PM AST Sat Jan 17 2026

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

.KEY MESSAGES...
Issued at 1241 PM AST Sat Jan 17 2026

* Marine and beach conditions will continue to deteriorate this
  evening, resulting in hazardous seas and a high risk of rip
  currents. Small Craft and beachgoers are encouraged to exercise
  caution and follow the flag warning system respectively.

* Breezy to windy conditions could lead for unsecured items to be
  blown around, with outdoor objects potentially displaced in the
  most exposed locations.

* Trade wind passing showers will continue across the local waters
  and windward sections, resulting in slippery roads and ponding
  of water in low-lying and poor drainage areas.

&&

.Short Term(This evening through Monday)...
Issued at 1241 PM AST Sat Jan 17 2026

During the early morning hours, a pronounced wind surge moved across
the U.S. Virgin Islands and progressed westward across Puerto Rico
by mid-morning. This feature produced a brief period of isolated to
scattered showers accompanied by gusty winds. While some showers
were occasionally moderate, they were fast-moving, resulting in
minimal rainfall accumulations. Surface observations indicated gusts
in the upper 20s to low 30s mph across the smaller islands and
exposed coastal areas of Puerto Rico, with a peak wind gust of 36
mph reported at the Henry E. Rohlsen Airport.

In the wake of the wind surge, a notable intrusion of dry air has
overspread the region. GOES-19 precipitable water imagery indicates
PWAT values near 1.0 inch, well below climatological normals for
this time of year. This has resulted in clearing skies and fair
weather conditions, which are expected to persist through the
remainder of the afternoon hours. Despite improving sky conditions,
breezy to locally windy conditions will continue, particularly along
the coasts and higher elevations, as a tight pressure gradient
remains in place.

For the remainder of the short-term period, the overall forecast
remains largely unchanged. Moderate to fresh easterly trade winds
will persist tonight through Sunday, maintaining breezy to locally
windy conditions across much of the area. The prevailing dry air
mass will limit shower activity, with any passing showers remaining
brief and shallow, mainly affecting windward coastal areas during
the nighttime and early morning hours. No significant rainfall
accumulations are expected, though brief ponding in poor drainage
areas cannot be completely ruled out.

By late Sunday into early Monday, a modest increase in low-level
moisture may allow for a slight uptick in passing trade-wind
showers, particularly across eastern and northeastern Puerto Rico
and the U.S. Virgin Islands. Even so, overall conditions will remain
generally fair, with wind-related hazards continuing to be the
primary concern. Residents should remain alert for gusty winds,
especially in exposed locations, while outdoor conditions outside of
brief showers will remain favorable.

&&

.Long Term(Tuesday through next Friday)...
Issued at 415 AM AST Sat Jan 17 2026

Model guidance continues to support a transition toward a wetter
and more unsettled pattern beginning Tuesday and persisting through
at least Friday, with the most active period expected after
Wednesday. Precipitable water values are forecast to increase to
above 1.75 inches, which is in the range of  above normal values
for this time of year and indicative of a deep tropical moisture
plume over the region. This moisture, combined with persistently
high mid- level relative humidity, will favor frequent shower
activity across the islands. Low-level winds are expected to
remain generally from the east to northeast and sustained in the
17 to 20 mph range, which should help maintain adequate
ventilation while still allowing for periods of locally enhanced
rainfall where showers align with terrain or convergence zones.
Temperatures are forecast to gradually trend back toward seasonal
norms, generally near the 50th percentile for this time of year
after midweek.

Tuesday is expected to mark a gradual transition toward a wetter
pattern. While a drier air mass is forecast to remain well south of
the area, guidance suggests that low concentrations of Saharan
air particles may still intermittently filter across the region.
Despite this, sufficient low- to mid-level moisture should remain
in place to support showers, particularly during the afternoon and
evening hours.

The wettest and most unstable portion of the forecast period is
expected after Wednesday. While 500 mb temperatures are now forecast
to remain closer to normals (around -6 to -7 degrees Celsius),
the combination of anomalously high moisture and enhanced low- to
mid-level convergence will support thunderstorms. Periods of
moderate to locally heavy rainfall will be possible, with showers
capable of redeveloping and frequently filtering over the same
areas for extended durations, and with the heaviest thunderstorm
activity expected during this period. As a result, the threat for
localized flooding will increase, especially in urban and poor
drainage locations.

Overall, while shower coverage and intensity will fluctuate
through the period, the greatest concern remains after Wednesday,
when periods of heavy rainfall may lead to localized flooding,
particularly in urban and poor drainage areas. This same time
frame will also carry the highest risk for lightning associated
with embedded thunderstorm activity. Winds are expected to remain
generally from the east to northeast in the 17 to 20 mph range,
which may limit widespread flooding but still allow for locally
enhanced rainfall in favored areas. Temperatures are expected to
remain near seasonal norms, with no significant heat impacts
anticipated.

&&

.AVIATION...
(18Z TAFS)
Issued at 1241 PM AST Sat Jan 17 2026

VFR conds expected at all terminals through the fcst pd. Limited
SHRA activity due to a dry airmass, with only brief VCSH psbl mainly
across USVI and E PR terminals. No sig flight restrs anticipated.
ENE winds 1525 kt with gusts up to 30 kt will result in windy
conds, esp at exposed coastal terminals.

&&

.MARINE...
Issued at 1241 PM AST Sat Jan 17 2026

A broad surface high pressure will continue to strengthen over the
central Atlantic today, promoting fresh to locally strong
easterly winds. This, combined with the arrival of a long- period
north-northwesterly swell, will result in choppy to rough seas,
leading to hazardous marine conditions for small craft. Hence,
Small Craft Advisories remain in effect for the local Atlantic
waters and offshore Caribbean, including the Mona and Anegada
Passage through at least Monday afternoon. Small craft operators
are urged to exercise caution.

&&

.BEACH FORECAST...
Issued at 1241 PM AST Sat Jan 17 2026

No changes were introduced to the beach forecast. Currently, the
moderate risk of rip current continues across northern and eastern
beaches of Puerto Rico, including Vieques and Culebra, and St.
Croix in the U.S. Virgin Islands. Low elsewhere. Conditions are
expected to deteriorate in the evening hours as strengthening
winds and a north-northwesterly long-period swell spreads across
the local waters and passages. Hence, a Rip Current Statement
remains in effect for the north and east-facing beaches of Puerto
Rico, including Culebra, and the U.S. Virgin Islands from 6 PM AST
tonight through 6 AM AST on Monday. Residents and visitors are
urged to follow the warning flag system and to opt for beaches
with lower risk such as the western and southern beaches of Puerto
Rico.

Besides rip currents, beachgoers should exercise caution due
breezy to windy conditions across the coastal areas of the
islands. Unsecured objects may blown around, with outdoor objects
potentially displaced in the most exposed locations.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk from 6 PM AST this evening through late
     Sunday night for PRZ001-002-005-008-012.

VI...High Rip Current Risk from 6 PM AST this evening through late
     Sunday night for VIZ001-002.

AM...Small Craft Advisory until 2 PM AST Monday for AMZ711.

     Small Craft Advisory from 6 PM this evening to 6 PM AST Sunday
     for AMZ712-716-726-733-741.

     Small Craft Advisory from 6 PM this evening to 2 PM AST Monday
     for AMZ723.

&&

$$

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

NWS SJU Office Area Forecast Discussion