326
FXCA62 TJSJ 240620
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
220 AM AST Fri Apr 24 2026

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

.KEY MESSAGES...
Updated at 215 AM AST Fri Apr 24 2026

* Pulses of northerly swell will continue into early next week, maintaining
  a moderate rip current risk along north-facing beaches of
  Puerto Rico, Culebra, Vieques, and the U.S. Virgin Islands, and
  occasionally producing locally hazardous marine conditions.

* Flooding risk remains limited overall, with locally elevated risk
  at times into early next week, mainly from slow-moving
  afternoon convection across Puerto Rico.

* A warming trend will develop through the weekend into early next week,
  with heat indices near or above 100F possible, especially in
  coastal and urban areas.

* Across the U.S. Virgin Islands, moderate rip current risk will
  persist, along with warmer conditions and periods of ponding of
  water possible early next week.

&&

.Short Term(Today through Sunday)...
Issued at 215 AM AST Fri Apr 24 2026

Tranquil conditions observed overnight will continue through the
morning hours, with mostly fair weather expected across Puerto
Rico and the U.S. Virgin Islands. A weak and evolving pattern will
persist, influenced by a fading frontal boundary just north of the
region and lingering troughing across the northeastern Caribbean.
Low-level flow will remain mainly east to southeast today,
gradually veering and supporting the onset of a warming trend.
With light to gentle winds and weak steering flow, afternoon
convection is expected to develop over the interior of Puerto Rico
due to diurnal heating and sea-breeze convergence, then expand
toward surrounding coastal areas. Activity should remain mostly
shallow to moderate, although slow-moving showers could produce
locally higher rainfall totals. An isolated thunderstorm cannot be
ruled out. A brief increase in winds is expected tonight into
early Saturday as the pressure gradient tightens slightly,
allowing for a few passing showers, mainly across windward areas.

Through the weekend, the boundary is forecast to transition into a
trough while lifting away from the region, with weak low pressure
development along this feature well to the northwest helping to
modify the regional flow. At the same time, a weak high over the
western Atlantic will drift southeastward and weaken, resulting in
a lighter pressure gradient and a more established southeasterly
to southerly wind pattern. Saturday should be somewhat drier
aloft, with subsidence and a persistent trade wind cap limiting
vertical development despite warmer conditions. By Sunday,
moisture is expected to increase and the inversion weakens,
allowing for greater cloudiness and more active afternoon
convection. Winds veering to the south to southwest may allow
activity to reach northern Puerto Rico, including the San Juan
metro area.

The primary hazard will be localized flooding from slow-moving
showers, mainly across interior and urban areas of Puerto Rico.
The risk remains limited today, decreases further on Saturday,
then increases slightly by Sunday as moisture deepens. Isolated
thunderstorms remain possible, and the warming trend will lead to
near to above normal temperatures by the end of the period.

&&

.Long Term(Monday through Friday)...
Issued at 215 AM 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...
(06Z TAFS)
Issued at 215 AM AST Fri Apr 24 2026

VFR conds will prevail at all TAF sites thru the fcst pd. Slow-
moving VCSH expected across all PR terminals btw 24/1622Z, and
across USVI terminals from late mrng onward. Winds lgt/vrb, bcmg
sea breeze dominated with speeds around 810 kt during the aftn,
then returning to lgt/vrb ovrnght.

&&

.MARINE...
Issued at 215 AM AST Fri Apr 24 2026

A weak frontal boundary meandering just north of the region will
continue to weaken and transition into a trough while lifting
away, while a surface high over the southwestern Atlantic shifts
east into the central Atlantic. This pattern will maintain light
east 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. Residual northerly swell will continue
to subside, with a small, long-period NNE swell expected to arrive
by Saturday into early next week with limited impacts. Overall,
marine conditions will gradually improve and remain below advisory
levels, although scattered showers may still produce locally
higher winds and seas.

&&

.BEACH FORECAST...
Issued at 215 AM AST Fri Apr 24 2026

A moderate risk of rip currents will persist through midweek
across the northern beaches of Puerto Rico, as well as Culebra,
Vieques, and the U.S. Virgin Islands. This means rip currents are
possible and can still be life-threatening, especially for
inexperienced swimmers. Conditions are expected to gradually
improve across the islands during the first half of next week as
the influence of long-period northerly swell diminishes.
Meanwhile, a low risk will continue along south-facing beaches.

&&

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

$$

EVE...DSR/GRS
MID...ICP

NWS SJU Office Area Forecast Discussion