332
FXCA62 TJSJ 291827
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
227 PM AST Sat Nov 29 2025

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

.KEY MESSAGES...
Issued at 220 PM AST Sat Nov 29 2025

* Occasional showers and isolated thunderstorms are expected this
  afternoon and evening, posing a limited risk of flooding across
  Puerto Rico and the US Virgin Islands.

* Breezy to locally windy conditions will prevail through at
  least Monday.

* The USVI and PR`s north and east-facing beaches have a moderate
  risk of life-threatening rip currents throughout the weekend.

* Pleasant temperatures will prevail across the USVI and PR
  throughout the forecast period.

* The 2025 Atlantic Hurricane Season ends tomorrow, November 30th.

&&

.Short Term(This evening through Monday)...
Issued at 220 PM AST Sat Nov 29 2025

Calm weather conditions with mostly sunny skies prevailed across
the US Virgin Islands and Puerto Rico during the morning hours.
Showers embedded in the easterlies moved over the US Virgin
Islands and the windward sections of Puerto Rico at times. Ponding
of water along roads and in poorly drained areas was observed
during this activity. Around noon, showers moved inland across the
interior and western sections of PR. This activity will continue
into the evening hours. Winds were mainly from the east at 15 to
20 mph, but locally higher near showers and thunderstorms. The St
Croix ASOS measured a wind gust of 36 mph (31 kt) this morning,
while at SJU airport, the maximum wind gust was around 28 mph (24
kt). Maximum temperatures were in the mid-80s or upper 80s along
the coast and in urban areas, and in the upper 70s or low 80s in
the mountains and valleys.

The ridge in the upper atmosphere will gradually weaken later
tonight and into Sunday evening as an upper-level trough moves in
from the west. This change is expected to increase instability,
especially on Sunday afternoon and evening. As the trough
amplifies over the Northeast Caribbean early next week, it will
create an inverted trough by Monday or Tuesday.

At the surface, the interaction between a surface high pressure
system over the central Atlantic and a cold front moving eastward
across the western Atlantic will likely support breezy to windy
trade wind conditions through at least Monday, when the surface
trough will weaken the local pressure gradient.

Given this pattern, there is a moderate (30-50%) chance of
occasional passing showers across the islands, especially over the
windward areas. This afternoon into the evening, showers are
expected to spread into the interior and western Puerto Rico, with
a moderate (40-50%) to high (60-70%) chance of rain. There is a
slight risk of flooding rains and isolated thunderstorms across
portions of the US Virgin Islands and eastern, interior, and
western Puerto Rico.

Although conditions are likely to be more unstable on Saturday
and even more by Monday, tradewind showers will continue at times,
with a moderate (30-50%) chance. These showers may extend inland
and into western Puerto Rico by the afternoon, with a moderate
(40-50%) to high (60%) chance of rain, especially across the
southwest quadrant due to the trade winds.

The atmospheric instability parameters indicate an increasing
trend in available instability over the US Virgin Islands and
Puerto Rico between Sunday and Monday, as 250 MB heights drop
below normal values (25th percentile), suggesting the presence of
an amplifying trough aloft. Additionally, 500 MB temperatures will
drop, cooling below normal, and steep lapse rates were observed
at low and mid levels, which could promote the formation of
isolated to scattered thunderstorms. Thus, if conditions
materialize, we may see isolated to scattered thunderstorms as
well as a slight to elevated risk of flooding rains late Sunday
afternoon into the evening and by Monday afternoon.

&&

.Long Term(Tuesday through next Friday)...
Issued at 530 AM AST Sat Nov 29 2025

The forecast remains on track. From Tuesday into Wednesday,
expect northeasterly winds to weaken gradually. Precipitable water
(PWAT) values show fluctuating moisture levels but, overall,
remain near normal for this time of year (1.501.75 inches). This
moisture, combined with the northeasterly flow, will support
periods of passing showers, mainly affecting windward areas.
Afternoon convection also remains possible, particularly across
interior and southwestern Puerto Rico, where brief heavy downpours
may develop.

An upper-level trough will linger over the region through
midweek, and we will need to continue monitoring its evolution to
determine whether any of its features begin to reflect at the
surface and potentially influence local weather conditions.

Drier air is still expected to filter in, with PWAT values
dropping below 1.4 inches, accompanied by continued breezy
easterly winds by the weekend. Temperatures at 925 mb are forecast
to rise to near- average values, supporting seasonal surface
temperatures. No heat- related risks are anticipated at this time.

&&

.AVIATION...
(18Z TAFS)
Issued at 220 PM AST Sat Nov 29 2025

The 29/12Z sounding showed E winds up to 22 kt thru FL050, with
latest VAD wind profile giving a similar trend, supporting continued
low-lvl E flow. Mainly VFR thru period with E flow 1020 kt and ocnl
higher gusts. Aftn SHRA/TSRA psbl mainly over interior to W PR, with
VCTS impacting mostly TJPS/TJBQ and VCSH/SHRA impacting rest of
terminals at times. Brief MVFR in heavier showers, otherwise P6SM
with SCT/BKN 025050 diminishing aft 30/00Z.

&&

.MARINE...
Issued at 220 PM AST Sat Nov 29 2025

A surface high pressure over the Central Atlantic, interacting with
a cold front moving eastward across the western Atlantic, will
promote fresh to strong trade winds this weekend into early next
week. This will result in choppy to rough seas across most offshore
waters and passages, particularly those offshore Atlantic waters. An
upper-level trough will amplify from the west over the Northeast
Caribbean from late Sunday afternoon into early next week,
inducing an inverted surface trough east of the Lesser Antilles
by Monday and closer to the local islands by Tuesday. This
atmospheric feature will increase the risk of thunderstorms
across the local waters early next week.

&&

.BEACH FORECAST...
Issued at 220 PM AST Sat Nov 29 2025

The risk of life-threatening rip currents is moderate along north-
and east-facing beaches in northwestern, eastern, and southeastern
Puerto Rico, as well as in Vieques, Culebra, and the US Virgin
Islands. This risk will continue throughout the forecast period.
In other areas, while the risk is low, dangerous rip currents can
still occur near groins, jetties, reefs, and piers.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
AM...None.
&&

$$

MORNING CREW...CAM/CVB
EVENING CREW...LIS/GRS