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368
FXCA62 TJSJ 011651
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
1251 PM AST Fri May 1 2026

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

.KEY MESSAGES...
Updated at 1250 PM AST Fri May 1 2026

* The flood threat will remain elevated across the mountain ranges
  and western sections of PR through this afternoon.

* Across the U.S. Virgin Islands, passing showers expected through
  the evening hours, and a drying trend during the weekend.

* Fair weather conditions expected in general through the middle
  of next week. Locally induced showers still expected over NW PR.

* Warmer-than-normal temperatures will continue through the
  weekend, with heat indices reaching or exceeding 100F across
  urban and coastal areas.

&&

.Short Term(This evening through Sunday)...
Issued at 1250 PM AST Fri May 1 2026

Variably cloudy skies were observed across the U.S. Virgin
Islands today, while mostly sunny to partly cloudy skies
prevailed across Puerto Rico. Locally induced low-level clouds and
showers were developing around noon over el Yunque area and
downwind from the U.S. Virgin Islands. For the rest of this
afternoon, showers with isolated thunderstorms are still
expected to develop along the Cordillera and western PR, where
urban and small stream flooding is expected with the heaviest
showers. High temperatures were from the upper-80s to low 90s across
the lower elevations of the islands to the upper 70s and mid-80s
across the higher elevations. Winds were from the east-southeast
up to 10 mph with higher gusts at times and sea breeze variations
across the northern and western coasts of PR.

A drying trend is expected on Saturday and Sunday. The
precipitable water content is expected to drop from 1.70 inches
today to near 1.30 inches by Sunday afternoon. This is in response
to a building mid-to upper-level ridge from the west, bringing
drier air and more stable conditions in general across the
northeastern Caribbean. However, locally induced afternoon
showers are expected to develop over northwestern PR each
afternoon.

Additionally, warm to hot conditions will persist, especially
across coastal and urban areas, where daily highs will reach the
upper 80s to low 90s, with heat indices exceeding 100F. Therefore,
stay hydrated if outdoors, and take frequent breaks in shaded or
air-conditioned areas to mitigate the risk of heat-related
illness.


&&

.Long Term(Monday through next Thursday)...
Issued at 159 AM AST Fri May 1 2026

The long-term period will be mainly dominated by generally tranquil,
near-seasonal conditions across both Puerto Rico and the U.S. Virgin
Islands. Surface high pressure over the central Atlantic will
promote east to southeast winds at 8 to 15 mph throughout the
period. Aloft, a ridging pattern will persist through Wednesday,
supporting stable conditions. As mentioned in previous discussions,
the driest period is expected from Monday through Wednesday. A
drying trend will lead to improving conditions. Model guidance has
been somewhat variable over the past few days, previously indicating
below-normal moisture content and now suggesting near-normal values.
Nevertheless, PWAT values are expected to remain lower, around 1.5
inches or less. Combined with a mid to upper-level ridge, this will
enhance atmospheric stability. Afternoon showers may still develop
due to local effects and diurnal heating; however, coverage will be
limited and activity brief. Rain chances will range from 10 to 40
percent each afternoon across northwestern Puerto Rico.

By Thursday, moisture will increase back to near-normal levels as
patches of moisture move into the region. At the same time, an upper-
level trough will begin to amplify, briefly increasing instability
and the potential for shower development. However, the latest GFS
and ECMWF runs indicate that the trough will quickly move away,
allowing ridging to reestablish itself in the mid to upper levels as
early as Friday.

At 925 mb, temperature guidance continues to indicate above-normal
values (around the 75th percentile) for this time of year. Combined
with a prevailing east to southeasterly wind flow, warm conditions
will persist throughout the forecast period. Daytime highs will
range from the upper 80s to low 90s in coastal and urban areas, and
from the upper 70s to mid-80s in higher elevations. Heat indices
will reach the upper 90s to low 100s degrees F each day. A limited
heat threat will persist across urban, coastal, and low-elevation
areas. Residents and visitors should stay hydrated and limit
prolonged sun exposure during peak heating hours.

As a result, generally sunny and warm days will prevail, with some
light, wind-driven showers overnight and during the early morning
hours in windward areas, along with limited afternoon convection
across northwestern Puerto Rico. Thursday will have the best chances
for rainfall, but overall, minimal impacts are expected.

&&

.AVIATION...
(18Z TAFS)
Issued at 1250 PM AST Fri May 1 2026

Mainly VFR conditions are expected to prevail across all
terminals. However, locally induced SHRA/TSRA over central PR
should cause mostly -RA/VCTS across the PR terminals thru at least
01/22z. The 01/12z TJSJ sounding indicated ESE winds up to 6 kt
blo FL030.

&&

.MARINE...
Issued at 1250 PM AST Fri May 1 2026

A weak surface high pressure will build northeast of the region,
over the central Atlantic, through the weekend. Meanwhile, low
pressure areas with associated frontal systems will move mainly
across the western and north of the high pressure through next
week. This pattern will promote mainly light to moderate east to
southeast trades across the local waters during the next several
days. Seas will generally range between 3 and 5 feet, and occasionally
up to 6 feet, driven by a combination of local wind waves and a
small, long-period northerly swell.

&&

.BEACH FORECAST...
Issued at 1250 PM AST Fri May 1 2026

A moderate risk of rip currents will persist across the north and
eastern beaches of the islands. A small, long-period northeasterly
swell could promote locally higher breakers at times, and
occasionally stronger rip currents are possible along the north-
facing beaches of Puerto Rico through the weekend. Beachgoers
should exercise caution through the weekend across these areas.

For additional information, visit weather.gov/beach/sju.

&&

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

$$

SHORT TERM...DS
LONG TERM....YZR
AVIATION...DS

NWS SJU Office Area Forecast Discussion