773
FXCA62 TJSJ 281903
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
303 PM AST Sat Mar 28 2026

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

.KEY MESSAGES...
Issued at 258 PM AST Sat Mar 28 2026

* Elevated flooding risk through the forecast period in Puerto
  Rico: Repeated showers and thunderstorms may produce rapid water
  rises in urban areas, small streams, and flood-prone locations,
  with a risk of landslides in steep terrain.

* Localized flooding in the U.S. Virgin Islands: Passing showers
  and isolated thunderstorms may cause water to pond on roads and
  in low-lying areas, creating hazardous travel conditions.

* Daily afternoon thunderstorms expected: Thunderstorm
  development each afternoon will increase the risk of localized
  flooding and lightning hazards, especially in interior and
  western areas.

* Deteriorating marine and coastal conditions midweek: A long-
  period northerly swell arriving late Monday night through at
  least Thursday will lead to hazardous surf, increased rip
  current risk, and possible Small Craft Advisory conditions.

&&

.Short Term(This evening through Monday)...
Issued at 258 PM AST Sat Mar 28 2026

During the morning hours, most of the activity remains over the
Atlantic Offshore waters. Meanwhile, by mid-morning, rainfall in
the US Virgin Islands and Puerto Rico began to increase, with
heavy rain affecting the northern USVI, where Flood Advisories
were issued, as well as across the El Yunque Mountains near
Fajardo, Ceiba, and Naguabo, and for south PR from Ponce to Sabana
Grande. The Doppler Radar detected a strong convection along the
Cordillera Central and other portions in St Croix, Vieques,
Culebra, and PR. Maximum temperatures were in the mid-80s across
urban and coastal areas, and in the upper 70s in the mountains.
Winds were mainly from the northeast at 5 to 15 mph, with sea-
breeze variations and higher gusts.

The afternoon convection will persist through this evening. With
saturated soils and elevated rivers, the flooding risk will remain
elevated in some locations in PR, especially along the Cordillera
Central and in southern PR. to pose a flooding risk during the
period. Convection will gradually diminish overnight, though
showers and isolated thunderstorms will reform across the Atlantic
Waters and Caribbean Waters near the Anegada Passage, and some of
these showers will occasionally affect the northern and eastern
windward locations of PR and the US Virgin Islands.

A drier air mass will move in over the islands around Sunday,
reducing the coverage and longevity of the convection. Regardless
of this, under a northeasterly wind flow, pockets of moisture will
arrive at times over the windward locations in PR and the USVI,
followed by afternoon convection across portions of the interior
and southwest quadrant of PR, supported by local effects, a
lingering upper-level trough, and sea breeze variations.

As winds increase around Monday, moisture pooling will increase
over the region, potentially increasing the potential for showers
and thunderstorms, especially during the afternoon.

&&

.LONG TERM...
Issued at 417 AM AST Sat Mar 28 2026

Strong low to mid level high pressure will maintain a strong
northeasterly wind flow through much of the workweek. The steering
flow is expected to be at 15 to 25 kts. At the upper level, the jet
stream will maintain speeds of nearly 80 knots. Under the low level
winds, weak disturbances will stream at times across the islands.
This will maintain the probability of precipitation on the medium
and high side. In general, showery weather will persist for most of
the Virgin Islands and eastern Puerto Rico. Then, in the afternoon,
diurnal heating will trigger showers and thunderstorm along the
interior and western Puerto Rico. Because the winds are expected to
be strong, the risk of flooding will be mostly limited. Impacts may
include hazardous driving conditions due to low visibility and
ponding of water. In the west, urban and small stream flooding could
still occur, although not widespread.

&&

.AVIATION...
(18Z TAFS)
Issued at 258 PM AST Sat Mar 28 2026

All TAF sites should experience VRB conds. Aft convection will bring
-TSRA/+TSRA across PR, with TEMPOs in JBQ, JSJ, JPS, ISX, and IST
 btwn 28/18-22z, reducing VIS and leading to MVFR conds. Winds
 will weaken and become light and VRB aft 28/22z, strengthening by
 29/12Z, expect E winds btwn 10-15 kt with higher gusts at times.

&&

.MARINE...
Issued at 258 PM AST Sat Mar 28 2026

An unstable weather pattern will persist in the region through
this evening, leading to scattered showers and isolated
thunderstorms. A surface inverted trough located north of the area
will sustain light to moderate east-northeast winds at least until
Sunday, with winds increasing to moderate to fresh by Sunday
afternoon, resulting in choppy seas. Additionally, winds will pick
up after a cold front moves toward the region from the Western
Atlantic by Monday. Furthermore, another long-period northerly
swell will create hazardous marine conditions, expected to last
until at least Thursday. These conditions may be dangerous for
small craft operators.

&&

.BEACH FORECAST...
Issued at 258 PM AST Sat Mar 28 2026

A moderate risk of rip currents is expected along north- and
east-facing beaches of Puerto Rico and the U.S. Virgin Islands,
while a low risk will persist along south-facing beaches.

Conditions are expected to worsen from Monday night through
Thursday due to the arrival of a long-period northerly swell
combined with increasing winds. This combination is likely to
create life-threatening rip currents and dangerous surf conditions
along the north-facing exposed coastlines.

Beachgoers should exercise caution and remain aware of changing
marine conditions. Always swim near a lifeguard and follow local
safety guidance.

&&

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

$$

KEY MESSAGES/SHORT TERM/MARINE/BEACH FORECAST...CAM
LONG TERM....ERG
AVIATION...MMC

NWS SJU Office Area Forecast Discussion