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653
FXCA62 TJSJ 101424 AAA
AFDSJU

Area Forecast Discussion...UPDATED
National Weather Service San Juan PR
1024 AM AST Tue Mar 10 2026

...New AVIATION, FIRE WEATHER...

.KEY MESSAGES...
Issued at 1015 AM AST Tue Mar 10 2026

* Fresh to strong winds will continue to result in choppy to rough
  seas across the region through Wednesday.

* Breezy to locally windy conditions will continue across Puerto
  Rico and the U.S. Virgin Islands through Wednesday. Unsecured
  and outdoor objects may blow around.

* Frequent passing trade wind showers are expected to move over
  the region today, maintaining a limited flood threat.

* Across the U.S. Virgin Islands, quick passing trade wind
  showers will move at times, with a drying trend expected by the
  end of the week.

&&

.Short Term(This afternoon through Thursday)...
Issued at 1015 AM AST Tue Mar 10 2026

Overnight, scattered showers moved across the northern and eastern
coasts of Puerto Rico, Culebra, Vieques, and the U.S. Virgin
Islands, leaving minimal rainfall accumulations. Low temperatures
remained in the low to mid-70s across lower elevations and reached
the mid-60s in the mountains. Winds prevailed from the east at 5 to
10 mph, with gusts up to 20 mph, particularly over the U.S. Virgin
Islands and Vieques.

Today, weather conditions will remain similar to previous days, with
frequent passing showers across the region during the morning,
followed by afternoon showers over the interior and western portions
of Puerto Rico. A surface high-pressure system migrating from the
central to the eastern Atlantic will gradually weaken the pressure
gradient over the next few days. Consequently, a decrease in wind
speed is expected from Wednesday through the end of the period. At
the upper levels, a deepening trough will enhance instability aloft
before gradually weakening on Thursday as it moves eastward.

Regarding moisture, a drier air patch is expected to move across the
islands today, with precipitable water (PWAT) values reaching up to
1.40 inches. However, wetter conditions will return by early
Wednesday as another moisture patch reaches the region, increasing
PWAT values to 1.70 inches. The 500 mb temperatures will remain cool
through Thursday, ranging from -9C to -11C, further supporting the
potential for a few thunderstorms. Seasonal temperatures will
persist as 925 mb levels remain within normal climatological values.
Highs will stay in the mid-80s across lower elevations and range
from the upper 70s to low 80s in the mountains.


&&

.Long Term(Friday through next Tuesday)...
Issued at 1015 AM AST Tue Mar 10 2026

Unstable weather conditions will persist across the local islands
for the first part of the long-term forecast. At the upper levels, a
strong jet stream exceeding 100 mph will continue to generate
divergence aloft, resulting in favorable conditions for vertical
development of showers and thunderstorms. Combined with this upper-
level feature, recent model guidance suggests decent amounts of
moisture in the lower levels, with precipitable water values
slightly reaching climatological normals of 1.20 to 1.50 inches.
This pattern will drive the appropriate conditions for afternoon
convection, especially across the interior and northeastern
sections, as well as the southwest quadrant due to a wind shift more
toward the east-northeast. From Saturday onward, a broad surface
high pressure will shift further east into the western Atlantic,
reducing the pressure gradient and allowing the islands to
experience moderate easterly winds of 10 to 15 mph, with gusty
conditions near the coastal areas and in the vicinity of showers.
For much of Saturday, slightly drier air will dominate, limiting
shower chances across the region. However, on Sunday, increased
moisture from the east will filter into the region, enhancing
convective chances once again. As a result, Saturday looks to be the
day with the least rainfall potential, while Sunday shapes up as the
wettest day of the weekend. Upper-level instability will persist
through Saturday into Sunday, continuing to support shower and
thunderstorm development during the afternoon hours.

For Monday into Tuesday, stable conditions will dominate at the
upper levels, characterized by a mostly zonal flow and warmer
temperatures at 500 mb, effectively suppressing deep convective
development across the region. The lack of upper-level support,
combined with a more stable atmospheric profile, will limit the
vertical development of showers throughout the day. As a result,
mostly sunny skies are expected across coastal and nearshore areas,
with good periods of sunshine throughout the day. Although the
overall pattern will remain stable, the afternoon diurnal heating
peak will still be sufficient to trigger isolated convective showers
across the interior sections. Rainfall amounts associated with these
afternoon showers are expected to remain light to moderate, with no
significant flooding concerns anticipated at this time. Temperatures
will trend warmer under the influence of a stable, mostly sunny
pattern, with coastal highs expected to reach the upper 80s to near
90 degrees.

&&

.AVIATION...
(12Z TAFS)
Issued at 1015 AM AST Tue Mar 10 2026

Mainly VFR conditions are expected to prevail across all terminals
through the forecast period. However, quick trade wind SHRA will
move at times across the area terminals, causing brief MVFR cigs.
The 10/12z TJSJ sounding indicated east winds up to 28 knots blo
FL050.

&&

.MARINE...
Issued at 1015 AM AST Tue Mar 10 2026

Seas will remain up to 7 feet across the offshore waters due to
steady moderate to fresh easterly winds resulting from a broad
surface high pressure extending across the Central Atlantic.
Therefore, Small craft advisories will remain in effect for all
the exposed waters and local passages until tonight. In nearshore
and coastal waters, seas will remain 5 to 6 feet, resulting in
choppy marine conditions. Surface winds will remain from the east
between 15-20 knots with gusty winds. Small craft operators are
urged to exercise caution and check the latest marine forecasts
before venturing into the local waters. Improving marine
conditions are forecast from Wednesday into the second part of the
workweek.


&&

.BEACH FORECAST...
Issued at 1015 AM AST Tue Mar 10 2026

A broad surface high pressure will continue to result in moderate
to locally fresh easterly winds across the region. As a result,
wind-driven seas are forecast for most of the offshore Atlantic
waters, with seas up to 7 feet. Along the coastal areas, choppy
seas are expected, ranging between 5 to 6 feet and winds up to 20
knots, with gusty conditions during the day due to temperature
variations. Therefore, a moderate risk of rip currents is expected
to prevail across all exposed coastlines today through the rest
of the week, including the northern, western, southern, and
southeastern beaches of Puerto Rico, as well as Culebra and the
U.S. Virgin Islands. Beachgoers are urged to exercise caution and
remain alert to changing surf conditions. For more detailed
information, visit: www.weather.gov/sju/marine.

&&

.FIRE WEATHER...
Issued at 1015 AM AST Tue Mar 10 2026

The KBDI remains above critical fire weather thresholds in Cabo
Rojo (669) and below thresholds in Guanica (519) and Camp
Santiago (383). Breezy to windy easterly winds will continue
between 14 to 19 mph with higher gusts up to 30 mph. Today, RH
values will drop near and below critical levels at times as a
patch of drier air filters into the area by mid-morning. Passing
showers will continue to move across the area from time to time;
however, drying soils, lower humidity later in the day and and
strong winds will maintain a moderate fire danger risk today. From
Wednesday onwards, winds are expected to become more light to
moderate and RH are expected increase due to the arrival of a
surge of moisture. At this time an RFD will not be issued. We
urge partners to continue monitoring updates during the morning
for a possible elevated fire danger risk if conditions warrant.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
AM...Small Craft Advisory until noon AST Wednesday for AMZ711.

     Small Craft Advisory until noon AST today for AMZ723-733-741.

&&

$$

SHORT TERM/FIRE WEATHER...GRS
LONG TERM...LIS
AVIATION...DSR

NWS SJU Office Area Forecast Discussion