379
FXCA62 TJSJ 241831
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
231 PM AST Fri Apr 24 2026

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

.KEY MESSAGES...
Updated at 225 PM AST Fri Apr 24 2026

* The arrival of northeasterly swell pulses will keep the risk of
  life-threatening rip currents moderate to high along these
  beaches from the weekend into early next week.

* Afternoon convection will maintain a limited flooding risk each
  day across Puerto Rico, with the risk becoming elevated from
  Sunday into early next week.

* The PR and USVI regions are expected to experience warmer-
  than-normal temperatures starting around Sunday, with heat
  indices reaching or exceeding 100F.

&&

.Short Term(This evening through Sunday)...
Issued at 225 PM AST Fri Apr 24 2026

In general, the US Virgin Islands and Puerto Rico observed little
or no rain, with mostly clear skies this morning. However, by
noon, showers affected St Croix and eastern PR, where periods of
moderate to locally heavy rain formed. Maximum temperatures ranged
from the mid-80s to the low-90s at coastal sites and from the
upper-70s to mid-80s at mountain sites. The winds calm to light
and variable under the influence of sea breeze variations.

This afternoon, under a southerly wind flow, showers will
continue to move across St Croix and the southern sections of PR
at times. Additionally, we cannot rule out showers developing
across the mountains and surrounding slopes, where a limited risk
of flooding rains remains. Across the northern U.S. Virgin
Islands, generally calm conditions are expected, with some showers
brushing the islands or forming downwind of them. We cannot rule
out showers tonight and overnight as the southerly winds advect
additional moisture to the southern and eastern portions of PR and
the USVI.

Model guidance shows instability increasing as a mid to upper-
level trough moved over the region from the west. However,
available moisture is near or below normal on Saturday, but it
might increase by Sunday, as model guidance now indicates. The
weak steering wind flow will maintain a limited risk of flooding
on Saturday. Under the aforementioned weather pattern, the best
chance of strong thunderstorms is on Sunday as moisture and
instability increase, when the flooding rain risk is elevated.
Still, the limiting factor observed includes a somewhat drier air
mass at mid levels, which could inhibit widespread activity, even
though available moisture will increase at lower levels.

The southeasterly flow will bring warmer-than-normal temperatures
and increased heating on Sunday. This will lead to an active
afternoon convection cycle, with showers developing in the
interior and moving north, potentially resulting in isolated
thunderstorms. Higher moisture levels and stronger heating will
enhance rainfall efficiency, raising the chance of locally heavy
rain and a slight risk of excessive rainfall.

&&

.Long Term(Monday through next Thursday)...
Issued at 225 PM AST Fri Apr 24 2026

A strengthening high-pressure system over the central Atlantic will
maintain a consistent south-southeasterly wind flow across the
region. Simultaneously, a deepening upper-level trough will create
unstable conditions aloft. This pattern will bring abundant moisture
from the Caribbean into the islands, significantly increasing the
potential for showers and thunderstorms.

A gradual increase in moisture is expected from Monday through
Wednesday, with precipitable water values reaching up to 2.25
inches; the bulk of this moisture is anticipated to arrive by
Tuesday afternoon. Consequently, shower activity is anticipated
during the morning hours across the U.S. Virgin Islands and eastern
Puerto Rico. By the afternoon, the combination of daytime heating,
local effects, and abundant moisture will likely trigger moderate to
heavy rainfall across the interior and western portions of Puerto
Rico. While temperatures at 500 mb will remain near seasonal
averages (between -7 to -8C), there is sufficient atmospheric
dynamics to support thunderstorm activity.

As winds prevail from the south-southeast, temperatures at the 925
mb level will rise well above climatological norms from Monday
through the latter part of the week. Maximum surface temperatures
are expected to range from the upper 80s to low 90s in coastal and
urban areas, and the low to mid-80s in higher elevations. Due to
high humidity values and southerly flow, heat indices will likely
surpass 100F daily. Residents and visitors are strongly encouraged
to prioritize hydration and limit prolonged sun exposure to stay
safe during this period of excessive heat.

&&

.AVIATION...
(18Z TAFS)
Issued at 225 PM AST Fri Apr 24 2026

VFR are expctd to persist across TAF sites, with -SHRA/+SHRA
bringing VCSH through 24/23z. -SHRA will continue for ISX, reducing
CIGs/VIS, and may briefly bring MVFR conds. AMDs will be issued if
required. Winds will once again weaken and become VRB over PR sites,
while USVI sites will remain light from the SE around 10 kt. Winds
will gradually increase btwn 5 - 12 kt by 25/12-14z.

&&

.MARINE...
Issued at 225 PM AST Fri Apr 24 2026

A weak frontal boundary meandering just north of the region will
continue to weaken and transition into a trough as it lingers near
the northeast Caribbean region and lifts north of it. At the same
time, a surface high over the southwestern Atlantic shifts east
into the central Atlantic. This pattern will maintain light east-
southeast to southeast winds today, followed by a brief increase
and a veering to a more southerly flow into early Saturday before
easing again through the weekend. Pulses of northeasterly swell
will move across the Atlantic Waters and Caribbean Passages during
the weekend and early next week.

&&

.BEACH FORECAST...
Issued at 225 PM AST Fri Apr 24 2026

Beachgoers, there is a moderate risk of life-threatening rip
currents along the north-facing beaches from Rincon to Fajardo, as
well as on the northern beaches in Culebra, Vieques, St. Croix,
St. Thomas, St. John, and adjacent islands. These conditions will
last through much of the forecast. However, the arrival of
occasional pulses of northeasterly swell will promote a
moderate/high chance of rip currents along these locations. We
encourage active monitoring of beach conditions for additional
updates.

The risk of rip currents will be low in the south-facing beaches
of Puerto Rico and the U.S. Virgin Islands.

In addition, beachgoers should remain alert for afternoon
thunderstorms, particularly across western Puerto Rico. These
storms may produce gusty winds and frequent lightning.

&&

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

$$

MORNING CREW...CAM/MNG
EVENING CREW...DS/GRS

NWS SJU Office Area Forecast Discussion