635
FXCA62 TJSJ 161810
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
210 PM AST Sun Nov 16 2025

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

.KEY MESSAGES...
Issued at 210 PM AST Sun Nov 16 2025

* Cloudiness is inhibiting afternoon convection, but a slight
  chance of locally heavy showers across north-central to
  northwest Puerto Rico prevails this afternoon. Mainly fair
  weather overnight.

* More frequent showers and isolated thunderstorms are likely late
  Monday into Tuesday across the U.S. Virgin Islands and eastern
  Puerto Rico.

* Slow-moving showers and isolated thunderstorms will increase
  the flooding and lightning risk from the interior to western
  portions of Puerto Rico Monday afternoon.

* The risk of rip currents will likely increase to high along the
  north and east facing beaches of Puerto Rico and portions of the
  U.S. Virgin Islands from around Monday through Wednesday.

&&

.Short Term(This evening through Tuesday)...
Issued at 210 PM AST Sun Nov 16 2025

Satellite and Doppler radar imagery show scattered to numerous
showers moving inland from the Mona Passage into western Puerto
Rico early in the morning, spreading further inland over the
interior and north PR around noon. Meanwhile, GOES-East imagery
indicated a dense cloud layer spreading across most of Puerto
Rico and the northern US Virgin Islands in the morning, covering
the rest of the islands by around noon. At the same time, St.
Croix mainly experienced sunny skies, but cloudiness began to
increase around noon. The US Virgin Islands and eastern PR enjoyed
calm weather with plenty of sunshine and pleasant temperatures.
Maximum temperatures in PR coastal sites and the USVI ranged
around the mid-80s, with some locations on eastern St. Croix
reaching the upper 80s, while mountains and valleys reached values
around the low 80s. The winds had a southerly component but were
generally calm to light and variable, with fluctuations due to sea
breezes.

This afternoon and into the evening, the fading frontal boundary
and a pre-frontal trough to the north, along with very weak
steering winds, will sustain a slight to moderate chance of slow-
moving showers. Meanwhile, an upper-level trough will continue to
create a relatively unstable atmosphere. Cloud cover will limit
the amount of heating across the islands, making it challenging to
initiate the afternoon convection. Additionally, instability will
slowly decrease overnight; thus, we will update the chance of
strong convection to slight to moderate due to the amount of cloud
cover, which is hindering its formation. Moisture levels remain
near normal, but the weak steering wind flow supports a high
probability of slow storm motion, which increases the likelihood
of prolonged rain activity over the same place; most likely over
the PR`s western half. Currently, this activity is light to
moderate, but there is still a slight chance that periods with
localized heavy rain may form. Conditions have a moderate chance
of improving late tonight as slightly more stable air moves in.

The east to east-southeast winds will return as a surface high
pressure builds over the Central Atlantic, while a more zonal flow
develops at mid-levels, favoring slightly drier air aloft. This
setup supports a low to moderate chance of showers and thunderstorms,
with the greatest coverage expected during the afternoon across
the central interior and northwestern Puerto Rico. Although Monday
night carries a low chance of additional development, an approaching
surface trough will bring an increase in moisture late Monday
night into Tuesday morning. This moisture increment will create
the best chance for occasional showers, first near St. Croix and
Vieques, then across the northern USVI, Culebra, and eastern PR.
Then, we expect a low to moderate chance of afternoon showers and
thunderstorms, primarily focused in the central interior and
extending west-southwest into Puerto Rico.

Regarding local temperatures, they will continue to be slightly
above normal, but heat impacts remain unlikely, and a cooling
trend is likely on the horizon.

&&

.Long Term(Wednesday through Sunday)...
Issued at 334 AM AST Sun Nov 16 2025

No major changes were introduced to the long-term forecast, as
weather conditions are expected to gradually improve over the
period. A polar trough should deepen sufficiently into the tropics,
cooling mid-level temperatures (between -8 and -9 degrees Celsius)
and increasing stability aloft. Additionally, the latest model
guidance suggest that the remnants of a frontal boundary should move
across the region by Wednesday, increasing moisture content.
Although the deterministic guidance of the GFS and ECMWF suggests
that Precipitable Water values will remain seasonal (1.6 - 1.8
inches), showers and isolated thunderstorms should increase flooding
and lightning potential, particularly over portions of interior and
southwestern Puerto Rico. Rainfall accumulations will likely promote
ponding of water over roadways, urban and poorly drained areas, with
isolated urban and flooding risk. By Friday, a surface high-pressure
system should build over the western Atlantic and mainly promote
winds with a northerly component. Additionally, winds are very
likely to increase,  promoting locally breezy conditions mainly over
the coastal areas of the islands. For the upcoming weekend, patches
of moisture will move occasionally across the islands, with mostly
passing showers across the local waters and passages, moving over
windward sections in the morning hours and afternoon convection over
interior and southern portions of Puerto Rico.

From the latest deterministic guidance, both GFS and ECMWF suggest a
tendency of 925 mb temperatures to decrease during the period.
Although ECMWF is warmer, both model solutions suggest temperatures
below climatological normal (below 20 degrees Celsius). Given the
expected weather conditions and temperatures, the heat risk will
remain low during the period.

&&

.AVIATION...
(18Z TAFS)
Issued at 200 PM AST Sun Nov 16 2025

A cloud layer will result in BKN-OVC CIGs btwn FL025-FL060 across
PR/USVI, persisting for the rest of this afternoon into the evening.
Cloudiness will slowly dissipate overnight into tomorrow. -SHRA/SHRA
will remain possible across portions of the islands, affecting JBQ
and briefly the rest of the terminals thru at least 16/23z.
SHRA/TSRA will return tomorrow, briefly affecting IST/ISX, JSJ/JBQ
from 17/15-17/23 UTC. We expect Light/VRB winds from the S-SSW and
with sea breeze, returning from the E-ESE tomorrow after 17/13z.

&&

.MARINE...
Issued at 200 PM AST Sun Nov 16 2025

A fading frontal boundary and a pre-frontal trough to the north
will continue to support a light south to southeasterly wind flow
through Monday. As these features dissipate, a surface high pressure
system will begin to dominate across the central Atlantic, promoting
moderate easterly winds from Monday night onward. Additionally,
pulses of a north to northeasterly swell will spread across the
local Atlantic waters and passages during the first half of the
week, increasing wave heights to around 4 to 5 feet. A second
surface frontal boundary will approach north of the region around
midweek, promoting moderate winds to shift more from the northeast
at the end of the forecast period. Daily showers and isolated
thunderstorms could generate locally hazardous conditions for
small craft.

&&

.BEACH FORECAST...
Issued at 200 PM AST Sun Nov 16 2025

A moderate risk of rip currents will continue this evening, mainly
along north and east-facing beaches of Puerto Rico, Culebra, and
the U.S. Virgin Islands. Beachgoers are encouraged to use caution
and swim near a lifeguard, as a moderate risk means life threatening
rip currents are possible. Beaches along western and southern
Puerto Rico and Vieques will maintain a low risk.

Beginning tomorrow, Monday, pulses of a north-northeasterly swell
are expected to deteriorate beach conditions. As a result, a moderate
to high risk of life-threatening rip currents is anticipated for
north- exposed beaches through at least Wednesday. For more information
specific to your location, visit weather.gov/beach/sju.

Additionally, afternoon thunderstorms may bring lightning and gusty
winds. Beachgoers should stay weather-aware for sudden changes in
weather conditions and seek shelter immediately if they hear
thunder.

&&

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

$$

SHORT TERM/AVIATION...CAM
LONG TERM...MNG
MARINE/BEACH FORECAST...YZR