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105
FXCA62 TJSJ 220705
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
305 AM AST Sun Mar 22 2026

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

.KEY MESSAGES...
Issued at 300 AM AST Sun Mar 22 2026

 * A more unsettled weather pattern is forecast for today into
   Monday with the arrival of a frontal boundary and an induced
   surface trough. There is an elevated flood risk today across
   the eastern interior, where urban and low-lying areas are
   expected to flood, along with rapid rises in small streams.

 * There is a limited lightning threat across the area as the
trough and the frontal boundary pass across the CWA.

 * There is a high risk of rip current across the northern
   coastal areas from Mayagez to Fajardo, and a small craft
   advisory across the offshore Atlantic waters.

 * A more variable weather pattern is forecast from Tuesday
   onwards when surface winds return from the east-northeast.

 * A low to moderate risk of rip currents exists across the
  coastal waters of Puerto Rico and the U.S. Virgin Islands.

&&

.Short Term(Today through Tuesday)...
Issued at 300 AM AST Sun Mar 22 2026

Deteriorated weather conditions persist across Puerto Rico during
the night and into the early hours on Sunday with the arrival of
the frontal boundary and the associated pre-frontal trough.
Satellite imagery showed a significant increase in cloud coverage
from west to east. Shower activity, on the other hand, remained
mostly over the local waters as shown by the Doppler Radar. The
peak of the showers affected the exposed Atlantic offshore waters
and, at 2 AM, moved near the coastal Atlantic waters, reaching the
west, north-central, and southeastern coastal areas. Overnight
temperatures were in the low 60s across the mountains and in the
mid 70s across the coastal areas.


Conditions will continue to deteriorate as the day evolves,
mainly due to the arrival of the deep moisture field from the
frontal system, with precipitable water values up to 2 inches, as
shown in satellite-derived imagery. This cloudiness and moisture
will continue to spread into the forecast area, enhancing the
potential for showers and isolated thunderstorms. Although the
more unstable areas of the upper-level trough remain moving well
to the north, influence from the deep system reflected at the
surface will enhance unstable weather pattern with +2 standard
deviation in RH % values between 850 to 500 MB and colder air
temperatures at 500 MB from -7 to -8 degrees This pattern will
enhance well- structured convection all day, especially across the
local waters in the morning and along land areas during the day.
An interesting wind pattern will also be present. At the surface,
calm to light winds will mostly come from the north-northeast, but
at 700 MB, more westerly winds will prevail. Given the expected 0
to 3 km wind pattern, the slow-moving showers will focus in the
interior, then drift to the eastern interior and the northeastern
quadrant. Therefore, the eastern interior will be the most
affected area, with a moderate risk of flooding, including urban
flooding in low- lying areas and rapid rises along small streams.
Rainfall accumulations will depend entirely on the movement of the
showers, and they could range from 1 to 2 inches, with higher
amounts in some areas.

On Monday, as the upper-level trough and the surface frontal
boundary move farther eastward, a transition to a more localized,
showery pattern is forecast. At the surface, patches of deep
moisture will hold along the eastern part of the CWA, between the
Culebra and Vieques municipalities and the U.S. Virgin Islands.
This moisture, along with local effects, will allow some pesky
passing showers to move in and out of the coastal areas of the
aforementioned locations. Additionally, surface winds will remain
from the north-northeast at 850 MB and from the west at 700 MB,
drifting the showers mostly across eastern PR and the coastal
waters. On Tuesday, surface winds veer from the east in response
to a surface high-pressure system establishing across the central
Atlantic and extending into the Caribbean. Moisture trapped in the
local region will continue to lead to cloudy skies and variable
weather.


&&

.Long Term(Wednesday through Sunday)...
Issued at 300 AM AST Sun Mar 22 2026

Moisture is expected to increase by mid-week as model guidance
indicates precipitable water (PW) values rising to between 1.50 and
2.00 inches, near the 75th percentile for this time of year and
therefore above normal. A weak mid- to upper-level trough moving
through the region, along with a weak surface perturbation, will
promote increasing cloud cover and frequent periods of showers.
Temperatures at 500 mb are forecast to be near 7 degrees C,
suggesting a moderate potential for instability. This could support
occasional heavier showers, although widespread organized convection
is not anticipated. The enhanced cloud cover will limit daytime
heating, keeping high temperatures near typical seasonal values for
March. Winds should remain generally light to moderate, with locally
higher speeds possible in and near shower activity. These unsettled
conditions are expected to persist through the end of the work week.

By the weekend, a gradual transition toward a drier airmass is
anticipated to filter across the islands, leading to decreasing
shower coverage and clear to partly cloudy skies. Despite the drying
trend, temperatures should remain relatively comfortable and
consistent with March.
&&

.AVIATION...
(06Z TAFS)
Issued at 300 AM AST Sun Mar 22 2026

Some MVFR to IFR conditions are expected across the PR TAF sites
due to the arrival of a frontal boundary. Winds will remain VRB
until 22/14Z, then peaking up to 10 knots from the N-NE and at 3
KM from the W. SHRA to TSRA will enhance BKN to OVC ceiling
affecting the FL020, FL030 & FL050, and with a reduction of VIS
with the strongest showers expected from 22/15Z to 22/21Z. Higher
gusts through the day are expected, mostly near the strongest
TSRA and SHRA.

&&

.MARINE...
Issued at 300 AM AST Sun Mar 22 2026

A frontal boundary approaching the region will bring unsettled
marine conditions today, with showers and the potential of
thunderstorms increasing across the local waters. A long-period
northerly swell will build hazardous seas across the Atlantic
waters. Behind the boundary, moderate to locally fresh northerly
winds will result in choppy seas, particularly across the Mona
Passage and offshore Atlantic waters. A surface high pressure
building from the western to central Atlantic will promote
northeasterly winds early this week, with increasing wind speeds
and seas by midweek.

&&

.BEACH FORECAST...
Issued at 300 AM AST Sun Mar 22 2026

Life-threatening rip currents will likely form along the north-
facing beaches of PR (from Rincon to Fajardo), with a moderate risk
of rip currents across Culebra and the US Virgin Islands. Beachgoers
should remain cautious, stay near lifeguards, and avoid entering the
water if unsure of conditions.Lower risk conditions are expected
along the more protected southern beaches, though caution is
still advised.

In addition, increasing moisture and instability associated with an
approaching frontal boundary will promote showers throughout the day
and possibly extend to Monday. Localized impacts, such as reduced
visibility and brief gusty winds, may occur near showers, creating
sudden hazardous conditions for beachgoers. There is a limited
thunderstorm risk, but any storms that develop could produce
lightning, posing a danger to those in or near the water. If
thunderstorms approach, seek shelter immediately.For additional
information and location-specific rip current details, please
visit: weather.gov/beach/sju

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk from 6 AM AST this morning through late
     tonight for PRZ001-002-005-008-010.

VI...None.
AM...Small Craft Advisory from 6 AM this morning to 6 AM AST Monday
     for AMZ711.

&&

$$

SHORT TERM & AVIATION...LIS
LONG TERM....MMC
MARINE & BEACH FORECAST...CAM

NWS SJU Office Area Forecast Discussion