835
FXCA62 TJSJ 271625
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
1225 PM AST Wed Aug 27 2025

.KEY MESSAGES...

* A Heat Advisory remains in effect through 5 PM this afternoon
  for all coastal and urban areas, as well as the valleys of the
  eastern interior of Puerto Rico. Southeasterly winds and
  increasing moisture content will increase the heat threat on
  Thursday and Friday. Extreme Heat Warnings and/or additional
  Heat Advisories are likely each day.

* For the U.S. Virgin Islands, heat advisory conditions are
  expected during the second part of the week, and passing showers
  will continue to move from time to time.

* Isolated thunderstorms are expected each afternoon over portions
  of the interior and western PR, and a slight chance downwind of
  el Yunque area into portions of San Juan and nearby counties.

* Seas will continue to subside across the regional waters during
  the next few days, and a low risk of rip currents is expected
  during the weekend across all beaches of PR and the USVI.


&&

.SHORT TERM...This afternoon through Friday...

Sunny to partly cloudy skies were observed through the morning
hours across the islands, with isolated thunderstorms developing
just before noon over portions of Toa Alta, Toa Baja, Dorado and
over Villalba and Vicinity. Across the USVI, streamers were
developing downwind of the islands, with the strongest showers
offshore of St. Croix. High temperatures were in general from the
upper 80s to low 90s across the lower elevations of the islands,
to the mid-70s and mid-80s across the higher elevations. The wind
was from the southeast between 12 and 18 mph with sea breeze
variations along the north and west coast of Puerto Rico.

For the rest of this afternoon, locally induced showers and
thunderstorms will continue to develop over the mountain ranges of
PR. As steering winds are from the east to southeast, showers will
drift along the northern and western coastal areas of PR. Locally
heavy rainfall is expected with this activity and urban and small
stream flooding is possible, as well as strong gusty winds with
the thunderstorms. Weak waterspouts cannot be ruled out between
the USVI and eastern coastal waters of PR. As clouds continue to
grow over land areas the heat indices are expected to drop a few
degrees, however, hot conditions will prevail in cloud free areas.

Increasing moisture from a weak tropical wave, currently located
just east of the Windward Islands will enhance the early morning
convection between the USVI and eastern PR, and during the
afternoon hours across most of the interior and west/northern
areas of PR on Thursday and Friday. Lighter steering winds are
expected by Friday, and slow-moving showers can lead to higher
rainfall accumulations over the same areas, increasing the flood
threat in general.

Also, the increasing moisture content with intense daytime heating
will cause heat indices to reach Extreme Heat Warning criteria on
both days, particularly before the onset of afternoon showers
across most coastal municipalities and valleys of the eastern
interior of PR. Across the USVI, similar conditions are expected
with Heat Advisory conditions likely, and approaching Extreme Heat
Warning criteria. In summary, the level of heat in Heat Advisory
conditions affects most individual sensitive to heat, and in
Extreme Heat Warning conditions the high heat indices will affect
anyone without effective cooling and/or adequate hydration.

.LONG TERM...Saturday through Tuesday...

/From Prev Disc Issued At 509 AM AST Wed Aug 27 2025/

The inherited forecast remains on track. From Saturday into early next
week, the pattern transitions back toward a more typical seasonal
weather pattern. Winds will gradually shift to a more consistent
easterly direction, carrying pockets of trade wind moisture across
the islands. Although the recent heat intensity will ease, heat
advisories remain possible throughout this period.

Moisture content is forecast to remain near climatological normals,
while only marginal instability is expected aloft. Overnight and
morning hours will favor passing trade wind showers moving in
across the U.S. Virgin Islands and the eastern half of Puerto
Rico. By the afternoon, stronger diurnal heating, sea breeze
interactions, and orographic influences will trigger additional
convection, primarily across the interior and western
municipalities of Puerto Rico. This afternoon activity could
generate brief heavy downpours, localized ponding of water, and
occasional lightning.

Through Monday and Tuesday, no significant large-scale disturbances
are anticipated, so the forecast confidence remains moderate to
high. The persistence of warm conditions and localized convective
activity will be the main themes.

Overall, the period will feature a return to a more seasonally typical
pattern of passing coastal showers at night and in the morning,
followed by scattered afternoon thunderstorms inland, with
continued but somewhat less extreme heat concerns.


&&

.AVIATION...

(18Z TAFs)

Mainly VFR conditions expected to prevail across all terminals
through the fcst period. However, tempo MVFR to brief IFR conds
are possible at TJBQ/TJSJ thru 27/22z due to locally induced
TSRA. Across the rest of the PR terminals, mostly VCTS expected
thru sunset, and VCSH throughout the period across the rest of the
local terminals of PR/USVI. Winds will continue ESE up to 16 kt
blo FL050, except in sea breezes at TJSJ/TJBQ thru 27/21z, and
bcmg light and variable at the sfc overnight.


&&

.MARINE...

Small craft operators should continue to exercise caution across
the Atlantic offshore waters and the Mona Passage due to a
lingering northerly swell promoting seas up to 6 feet across these
waters. Seas and winds will gradually subside during the next few
days. Shower and isolated thunderstorm activity could increase as
early as tonight due to an approaching weak tropical wave,
currently located east of the Lesser Antilles.


&&

.BEACH FORECAST...

A lingering northerly swell will continue to promote life-
threatening rip currents across the north, eastern, and western
beaches of PR, Culebra, St. John, and Saint Thomas through this
afternoon. Therefore, there is a High Rip Current Risk in effect
for these areas. Please refer to the latest Coastal Hazards
Message (CFWSJU) and Surf Zone Forecast (SRFSJU) for detailed
information for your area.


&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk until 6 PM AST this evening for PRZ001-002-
     005-008-010-012.

     Heat Advisory until 5 PM AST this afternoon for PRZ001>005-007-
     008-010-011.

VI...High Rip Current Risk until 6 PM AST this evening for VIZ001.

AM...None.
&&

$$

SHORT TERM...DSR
LONG TERM...MMC
AVIATION...DSR
BEACH/MARINE...DSR