558
FXCA62 TJSJ 191807
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
207 PM AST Wed Nov 19 2025

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

.KEY MESSAGES...
Issued at 206 PM AST Wed Nov 19 2025

* Life-threatening rip currents are expected along the north and
  east-facing beaches in Puerto Rico, Culebra, and St. Croix
  through Thursday afternoon.

* A surface trough moving across the region is resulting in
  showers across eastern into the interior of Puerto Rico and
  afternoon convection over portions of western Puerto Rico.

* Passing showers across the U.S. Virgin islands and its vicinity
  and eastern Puerto Rico are expected during the overnight
  hours.

* Drier air and cooler temperatures are anticipated from tomorrow
  into the weekend.

&&

.Short Term(This evening through Friday)...
Issued at 206 PM AST Wed Nov 19 2025

A surface trough, now mainly west of the islands, promoted afternoon
shower and t-storm activity over the region. Under easterly steering
winds, the highest radar estimated accumulations (1.5 in to around 2
inches) were observed mainly over interior to western PR, downwind
of Vieques, and over western metro area to north-central PR.
Satelite derived precipitable water (PWAT) values show around 1.75
to around 2 inches over the islands. The bulk of moisture associated
with the surface trough remained over the Caribbean Sea with PWAT
values above 2 inches. Maximum temperatures ranged from the mid-80s
to the upper 80s and/or low 90s along coastal and lower elevation
areas of the islands. Winds are forecast to back and become more
northeasterly later today, steering current showers and t-storms
towards the SW quadrant of Puerto Rico. A surface high over the
Atlantic and an induced surface trough from an upper-level trough
north of the islands will maintain northeasterly steering flow
through the rest of the period. By early tomorrow, this steering
flow will move the more humid air mass, with 1.8 to 2 inches of
PWAT, southward and away from the local islands. As gradually drier
air filters in, PWAT values are forecast to continue a decreasing
trend for the rest of the period. On Thursday, current model
guidance has PWAT values ranging from 1.5 to 1.7 inches and on
Friday, PWAT values are forecast at 1.1 to 1.4 inches. A patch of
even drier air, with PWAT values around 0.9 to an inch, is forecast
to approach the northern waters late Friday and reach the islands to
start the long term period. Although this drying trend is forecast,
the above mentioned mid to upper trough will approach the islands
tomorrow and Friday, eroding the current mid-level ridge, promoting
instability and resulting in 500 mb temperatures at slightly below
normal to normal values. Afternoon convective showers (with possible
isolated t-sotrms) can develop across interior to southwestern PR
under northeasterly flow, and advective showers will move over
northeastern coastal areas during the morning and night hours. 925
mb temperatures are forecast at low-end normal to below normal
values during the period.

&&

.Long Term(Saturday through Wednesday)...
Issued at 333 AM AST Wed Nov 19 2025

Confidence remains high for the upcoming weekend forecast, with
variability for the first part of the workweek. A surface high
pressure building over the western Atlantic will promote
northeasterly winds through most of the period. Saturday is
anticipated to be the driest day of the long- term, as a cold,
drier airmass filters into the region. From the latest model
solutions, Precipitable Water (PWAT) values should drop below
normal (1.0 - 1.2 inches), with some members suggesting values
below the 25th percentile (below 1.0 inch). In terms of
instability, with the presence of a mid-level ridge lingering
through the period, thunderstorm activity will likely remain
limited. Additionally, the Galvez- Davison Index (GDI) keeps
suggesting a potential for isolated shallow convection. As
mentioned in the previous discussion, patches of moisture are
still likely to arrive by early Monday, with PWAT values expected
to increase but remain below climatological normal (likely between
1.2 and 1.4 inches, with a low chance of reaching 1.6 inches).
The most likely scenario remains, with showers moving into
windward sections of the local islands each night into the
morning, with afternoon convection over the mountain ranges into
southwestern Puerto Rico. Under this weather pattern, rainfall
accumulations may not necessarily bring significant flood and
lightning potential.

As mentioned in previous discussions, the fall in temperatures is
expected to continue, with 925 mb temperatures remaining below
climatological normal, with Saturday being the coolest day of the
period. Once again, the heat threat will remain low for the rest of
the forecast period.

&&

.AVIATION...
(18Z TAFS)
Issued at 206 PM AST Wed Nov 19 2025

VFR conds are present across all TAF sites. Intermittent MVFR
conds possible over the next hours due to VCTS or TSRA with
reduced vis and lower cigs across TJBQ, TJSJ and TJPS, then will
decrease aft 19/22-23Z but may linger near TJSJ and USVI terminals
overnight. Winds will remain from the E at around 10 to 12 kts.
Lighter winds overnight, increasing near 10 kts aft 20/14Z. Winds
from the NE anticipated for Thursday.

&&

.MARINE...
Issued at 206 PM AST Wed Nov 19 2025

A surface trough will continue to bring a few showers and isolated
thunderstorms across the local waters and passages this afternoon
and tonight. Moderate easterly winds will gradually shift more
from the northeast tonight as a surface trough moves east of the
Leeward Islands. Winds will prevail from the northeast through
the weekend. Pulses of north-northeasterly swells will continue to
spread across the Atlantic waters and local passages through
Thursday afternoon.

&&

.BEACH FORECAST...
Issued at 206 PM AST Wed Nov 19 2025

Based on buoy observations, the high rip current risk was
extended through Thursday afternoon, as another pulse of a north-
northeasterly swell is expected to arrive tonight and peak around
Thursday morning. This will promote hazardous conditions for
beachgoers along northern and eastern beaches of Puerto Rico,
Culebra, and St. Croix in the U.S. Virgin Islands. Then, as that
pulse continues to fade, beach conditions will improve by late
Thursday night, with a moderate risk of rip currents prevailing
across the northern and eastern beaches of PR, Vieques, Culebra,
and the U.S. Virgin Islands. Nevertheless, beachgoers are
encouraged to swim near a lifeguard as life- threatening rip
currents are possible along the surf zone. For location-specific
information, visit weather.gov/beach/sju.

Aside from rip currents, beachgoers should be also aware of other
potential hazards such as lightning and gusty winds due to shower
and thunderstorm activity this afternoon and tomorrow that may
move over coastal areas. If thunder roars, go indoors!

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk through Thursday afternoon for PRZ001-002-
     005-008-012.

VI...High Rip Current Risk through Thursday afternoon for VIZ002.

AM...None.
&&

$$

SHORT TERM...MRR
LONG TERM...MNG
AVIATION...YZR