730
FXCA62 TJSJ 220838
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
438 AM AST Wed Oct 22 2025

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

.KEY MESSAGES...

 * For today, showers and thunderstorms will lead to flooding in
   urban areas, roads, small streams, and washes across southern
   municipalities, as well as some eastern and western areas.

 * High uncertainty remains in the upcoming forecast due to
   differing solutions among global model guidance regarding
   Melissas trajectory.

 * A fading northerly swell will continue to produce hazardous marine
   conditions across the offshore Atlantic waters and local
   passages, along with hazardous coastal conditions featuring
   large breaking waves and dangerous rip currents.

 * For the U.S. Virgin Islands, a variable weather pattern will
   persist, with brief passing showers potentially causing minor
   flooding in low-lying urban areas.

&&

.SHORT TERM...Today through Friday...
Issued at 412 AM AST Wed Oct 22 2025

Cloudy skies prevailed across the islands during the early morning
hours. Showers and isolated thunderstorms developed between the
eastern waters of Puerto Rico and the U.S. Virgin Islands. The
Doppler radar estimated up to 0.25 inches across the eastern
interior to just over an inch in eastern PR. Across the USVI,
accumulations were less than 0.10 inches. Minimum temperatures
ranged from the upper-70s to low 80s across the lower elevations of
the islands, and from the mid-60s to mid-70s across the higher
elevations of Puerto Rico. The wind was from the east to southeast
at 8 to 16 mph with gusts between 26 and 33 mph observed with the
showers.

Tropical Storm Melissa, located over the central Caribbean Sea, will
continue to promote higher moisture content over the Caribbean Sea
during the next few days, while moderate east to southeasterly
trades prevail across the area under the influence of TS Melissa and
from a weak surface high pressure building from the central
Atlantic. Embedded in this flow, higher amounts of precipitable
water content will move from the tropical Atlantic into the eastern
Caribbean, maintaining an overall wet pattern through the short-term
period. The general rainfall forecast over the next three days
remains the same, with total accumulations of 2 to 4 inches across
the CWA. Global and hi-res model guidance continues to suggest the
highest potential for rainfall along the southern and eastern half
of PR, particularly from Thursday through Friday. For the USVI,  an
advective weather pattern will persist, but as fast-moving showers
are expected, the total rainfall accumulations should remain under
the lower end of the forecast.

Overall, periods of heavy rainfall with localized flooding and gusty
winds can be expected across the islands through the short-term
period. There is no significant change to the temperature forecast,
as cloudy skies should limit the heat-related impacts during the
day, while minimum temperatures remain a few degrees higher than
usual.

&&

.LONG TERM...Saturday through Wednesday...
Issued at 412 AM AST Wed Oct 22 2025

High uncertainty persists in the long-term period across the
islands. Global guidance models have not shown significant changes
in their solutions from Saturday through the upcoming workweek due
to the proximity of what is now Tropical Storm Melissa. The GFS
guidance continues to indicate that the tropical system will move
northward into Hispaniola, keeping the islands under deep-layer
moisture with precipitable water values between 2.0 and 2.3
inches. This pattern in the GFS model will also favor a weak
pressure gradient and veering winds from 03 km, allowing mostly
southerly winds on Saturday into Sunday, shifting more toward the
west-southwest on Monday through Wednesday across the islands. In
contrast, the European model (ECMWF) suggests Tropical  Storm
Melissa moving northeastward between Jamaica and the western tip
of Haiti. This solution is quite similar to the official
trajectory from the National Hurricane Center, which keeps Melissa
moving slowly during the next several days. Similar to
yesterdays forecast, given these discrepancies, confidence in the
forecast from Saturday through Wednesday remains low to moderate.

For now, the forecast aligns with the National Hurricane Centers
outlook, calling for a variable and wet pattern with afternoon
showers and a 4080 percent chance of rain each day. The strongest
showers are expected from Saturday into Monday due to
precipitable water values ranging between 1.9 and 2.3 inches, well
above climatological normals. From Saturday into Sunday, the
southerly wind flow will push showers across the interior,
southern coastal areas, and northern sections. From Monday through
the rest of the workweek, winds could vary from south to west
depending on the final trajectory of Melissa. A more concise
forecast with low uncertainty is expected in the upcoming days as
model guidance begins to converge on a similar solution. &&

.AVIATION...
(06Z TAFS)
Issued at 412 AM AST Wed Oct 22 2025

SHRA/TSRA en route fm the Anegada Passage will cause -RA/VCTS
through the morning hours across the USVI and eastern PR terminals.
Meanwhile, outer rainbands from TS Melissa over the central
Caribbean Sea will continue to bring SHRA/TSRA across the Caribbean
waters and Mona Passage. This can lead to gusty winds around 30 kt
along the southern coast of PR, and tempo MVFR conds at times at
TJPS through the fcst period. Also, early afternoon SHRA/TSRA
expected to develop in and around TJSJ/TJBQ, which can lead to tempo
MVFR conds thru 22/20z. ESE winds at 12-16 kt with gusts up to 26 kt
and higher near SHRA/TSRA.

&&

.MARINE...
Issued at 412 AM AST Wed Oct 22 2025

A fading northerly swell will continue to result in seas up to 7
feet along the offshore Atlantic waters, and the local passages
today were small craft advisories, remaining in effect until 6 PM
AST today. At the surface, the islands will be mostly under a
moderate to locally fresh easterly wind flow today, resulting in
some areas with choppy seas during the day. Cloud coverage with
showers and thunderstorms from Tropical Storm Melissa will
continue to result in some localized hazardous marine conditions
across the Caribbean waters and the Mona Passage.

The marine forecast for the upcoming days remains highly
uncertain, mostly due to the final trajectory of Tropical Storm
Melissa.


&&

.BEACH FORECAST...
Issued at 412 AM AST Wed Oct 22 2025

Hazardous coastal conditions will persist today along the northern
and northeastern exposed beaches, including Culebra and St.
Thomas, due to large breaking waves up to 8 feet. These conditions
will maintain a life-threatening rip current risk for beachgoers.
Therefore, the High Rip Current Risk continues through 6 PM AST
for the aforementioned coastal areas. Beachgoers are urged to
remain out of these waters during the day. An improvement in
coastal conditions is forecast from Thursday into Friday; however,
coastal conditions can deteriorate again for the upcoming weekend.


&&

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

     High Rip Current Risk until 6 AM AST early this morning for
     PRZ010-011.

VI...High Rip Current Risk through this afternoon for VIZ001.

AM...Small Craft Advisory until 6 PM AST this evening for AMZ711-723-
     741.

     Small Craft Advisory until 6 AM AST early this morning for
     AMZ712-716-733.

&&

$$

SHORT TERM & AVIATION...DS
LONG TERM & MARINE....LIS

NWS SJU Office Area Forecast Discussion