278
FXCA62 TJSJ 011910
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
310 PM AST Sat Nov 1 2025

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

.KEY MESSAGES...
Issued at 257 PM AST Sat Nov 1 2025

* Weather conditions will improve by late tonight as a tropical wave
  moves west and drier, more stable air filters into the region.
  Expect limited shower activity mainly over interior and western
  Puerto Rico during the afternoons in the next few days.

* Across the U.S. Virgin Islands, weather conditions will also
  improve by this evening. Over the next few days, mainly fair
  weather is expected, with brief passing showers possible at times.

* Breezy east to east-southeast winds will persist, especially
  across coastal areas.

* A moderate risk of rip currents continues for most local
  beaches, and a Small Craft Advisory remains in effect for the
  offshore Atlantic waters through Sunday morning as rough seas
  persist.

&&

.Short Term(This evening through Monday)...
Issued at 257 PM AST Sat Nov 1 2025

Frequent heavy showers and isolated thunderstorms have affected much
of Puerto Rico and the U.S. Virgin Islands throughout the day as a
tropical wave moved across the region, producing strong wind gusts.
Earlier this morning, a 49 mph gust was recorded at Cyril E. King
Airport in St. Thomas, associated with a band of heavier showers
moving through the area. A Special Weather Statement was also issued
for portions of southern Puerto Rico (Guayanilla, Yauco, and
Penuelas) due to a line of strong showers that moved over the
region. The highest rainfall accumulations, up to around 1.5 inches,
were observed over eastern Puerto Rico, although spread over a
longer period as showers have been moving quickly but occurring
frequently. Through the remainder of the afternoon, showers and
isolated thunderstorms may still develop across interior and western
Puerto Rico.

On Sunday and Monday, model guidance shows a much more stable and
dry environment. Mid-level relative humidity values are expected to
drop below 20% by Sunday and even below 10% on Monday, coinciding
with the development of a strong inversion cap between 850700 mb.
This will significantly suppress vertical development and lead to
mostly fair weather conditions across the local islands. Only brief,
shallow showers are expected at times within patches of low-level
moisture moving across the area, mainly during the overnight and
early morning hours over windward coasts, and in the afternoon
across the interior and western Puerto Rico.

Surface winds will remain from the east-southeast at moderate
speeds, becoming more easterly by late Sunday as the Atlantic high-
pressure system strengthens north of the region. Winds at 925 mb are
expected to stay near or slightly above normal through the period,
maintaining breezy conditions, especially across coastal areas.

Overall, expect improving weather conditions tonight into Sunday,
followed by a drier and more stable pattern through Monday with
limited shower activity and seasonable temperatures.

&&

.Long Term(Tuesday through next Friday)...
Issued at 457 AM AST Sat Nov 1 2025

The long-term period appears to be dominated by variable weather
conditions. Based on the latest model guidance, the wind pattern
will be mainly influenced by a strong high pressure system over
the central Atlantic, promoting easterly winds for most of the
period. The pressure gradient will remain tight through at least
Tuesday night, as a result, breezy conditions are expected during
this time, followed by a decreasing trend on Wednesday and
Thursday.

At the mid to upper levels, a strong mid level ridge is expected
to persist and dominate most of the period, promoting stable and
drier conditions aloft. However, an upper level low moving south
of the area, over the Caribbean waters, will slightly weaken
atmospheric stability across the region and induce weak surface
troughs. According to the PWAT guidance, moisture content will
fluctuate from normal to below normal for most of the period, with
moisture mainly confined to the lower levels. This pattern will
allow patches of low level moisture to continue filtering into
Puerto Rico and the U.S. Virgin Islands. As a result, there will
be a low to medium chance (2040%) of occasional passing showers
over the windward portions of the U.S. Virgin Islands and eastern
Puerto Rico during the morning hours, followed by afternoon
convection across western Puerto Rico (5060%) driven by local
effects, available moisture, and marginal instability. At this
time, the flood risk is maintained at a limited level, primarily
for the western sectors of Puerto Rico each afternoon.
Additionally, a limited to no heat risk is likely to persist, as
indicated by a decreasing trend in the 500 mb and 925 mb
temperatures. This could support some thunderstorm development;
however, it will depend on the available moisture and the
persistence of the mid-level ridge.

&&

.AVIATION...
(18Z TAFS)
Issued at 257 PM AST Sat Nov 1 2025

Mainly VFR conds expected thru prd. However, brief MVFR/IFR conds
psbl in SHRA/TSRA with reduce VIS/CIGs as a tropical wave continues
to cross the region. Drier conditions after 02/04Z. SFC winds
ESE-SE 1218 kt with higher gusts in SHRA/TSRA, bcmg lgt/vrb aft
01/23Z, then incr to 1015 kt aft 02/13Z.

&&

.MARINE...
Issued at 257 PM AST Sat Nov 1 2025

A surface high pressure system over the central Atlantic and a
tropical wave moving across the region today will promote moderate
to locally fresh trade winds through the weekend. Additionally,
thunderstorm activity is expected across the local waters and
passages as the tropical wave moves through the region. Wind-driven,
choppy to hazardous seas are expected from this evening through early
Sunday, particularly across the offshore Atlantic waters, where a
Small Craft Advisory is in effect. Winds and seas are forecast to
improve early next workweek.

&&

.BEACH FORECAST...
Issued at 257 PM AST Sat Nov 1 2025

Breezy conditions will result in rough seas promoting a moderate
risk of rip currents for most beaches across Puerto Rico and the
U.S. Virgin Islands through the weekend.

Beachgoers should exercise caution, as life-threatening rip
currents are possible along the surf zones. Additional hazards
include showers and thunderstorms developing across coastal areas
for the rest of the afternoon. Therefore, beachgoers should
remain alert for sudden changes in weather conditions and seek
shelter immediately if thunder is heard. However, weather
conditions are expected to improve by tomorrow. Beachgoers are
encouraged to continue monitoring the beach forecast for updates
or changes. For detailed information in your area of interest,
please visit weather.gov/beach.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
AM...Small Craft Advisory from 6 PM this evening to 6 AM AST Sunday
     for AMZ711.

&&

$$

.MORNING CREW...CVB/RVT