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471
FXCA62 TJSJ 291810
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
210 PM AST Sat Aug 29 2026

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

.KEY MESSAGES...
Issued at 156 PM AST Sat Aug 29 2026

- The Heat Advisory remains in effect through 5 PM AST. A brief
  relief is expected Sunday into Monday before hazardous heat
  returns around midweek.

- Unsettled and windier conditions are expected tonight into
  Monday as moisture associated with the remnants of Tropical
  Storm Dolly move across the region. Lingering moisture may
  continue into Tuesday.

- The main hazards will be urban flooding, lightning, and gusty
  winds, especially tonight into Monday. The potential for
  isolated flash flooding is lower but cannot be ruled out.
  Rainfall amounts and the location of the highest totals remain
  uncertain.

- Marine and coastal conditions will become hazardous Sunday into
  Monday as winds and seas build. Small Craft Advisory is in
  effect for the offshore Atlantic waters and Anegada Passage. A
  high rip current risk statement will be in effect by Sunday.

&&

.Short Term(This evening through Monday)...
Issued at 156 PM AST Sat Aug 29 2026

Relatively calm and hot conditions prevailed across Puerto Rico and
the U.S. Virgin Islands today, with partly cloudy skies and only
a few showers, mainly across eastern Puerto Rico. East winds
remained around 6 to 18 mph with occasional higher gusts. High
temperatures reached the upper 80s to lower 90s across coastal and
urban areas, and despite the cloud cover, heat indices exceeded
100 degrees in the most heat-vulnerable areas. A transition to
wetter and more unsettled weather is expected tonight as a broad
tropical wave, associated with the remnants of Dolly, approaches
the islands.

Tonight into Sunday, moisture will increase from east to west, with
showers and thunderstorms becoming more frequent first across the
U.S. Virgin Islands, then over eastern Puerto Rico and then
spreading across the rest of Puerto Rico. Deepening tropical
moisture will support periods of heavy rainfall and squally
weather. The main hazards will be urban and poor-drainage
flooding, lightning, and gusty winds. A limited flooding risk is
expected across the U.S. Virgin Islands tonight, expanding into
Puerto Rico on Sunday, with the potential for an elevated
excessive rainfall risk where repeated rounds of heavy rainfall
occur. Ponding of water on roads and flooding of poorly drained
and urban areas could make travel hazardous, while stronger
showers and thunderstorms may produce brief strong wind gusts and
frequent lightning.

Unsettled conditions will continue Sunday night through Monday as
deep tropical moisture remains across the region. Additional
rounds of showers and thunderstorms could increase runoff and
flooding impacts, particularly where heavier rainfall repeatedly
affects the same areas. Although the rainfall should provide some
relief to ongoing dry conditions, it is not expected to end the
drought. Increased clouds and rainfall will also provide temporary
relief from the recent heat. Those with outdoor or travel plans
Sunday and Monday should be prepared for rapidly changing
conditions and monitor forecast updates, particularly regarding
the timing and location of the heaviest rainfall.

&&

.Long Term(Tuesday through next Friday)...
Issued at 156 PM AST Sat Aug 29 2026

Deep tropical moisture trailing from the previous tropical wave (the
remnants of Tropical Storm Dolly) will remain in place across the
forecast area on Tuesday, with GFS model guidance indicating
precipitable water (PWAT) values near the 75th percentile for this
time of year. At the surface, a weak disturbance (previous dolly)
positioned west of the region over Hispaniola will maintain a south-
southeasterly wind flow across the local islands. Under this
pattern, an unstable, wet weather pattern will prevail, favoring
some widespread showers with isolated thunderstorms across eastern
Puerto Rico, including the San Juan metro area in the morning hours
followed by afternoon showers along the interior west and
northwestern sections. By Wednesday, low-level winds will shift from
the east-southeast as surface high pressure anchors over the western
Atlantic and another extends across the Central Atlantic. This
configuration will bring a more variable moisture regime as pockets
of deep moisture alternate with drier air patches, resulting in hot
and warm conditions with heat indices that could reach 111 degrees
across coastal and urban sections. Although conditions will not be
favorable for morning advective showers, localized afternoon
convective development is expected over interior and western Puerto
Rico.

According to the model guidance today, Thursday is forecast to be
the driest day of the long-term period as a drier air mass filters
into the region, suppressing, in some way, widespread cloud
development and keeping maximum temperatures elevated across coastal
areas. On Friday, the surface high over the Central Atlantic will
extend further south, enhancing easterly trade winds that will push
occasional patches of trade wind moisture across the regional
waters. By late Friday into Saturday, global model guidance suggests
an increase in moisture associated with another tropical wave
approaching the local area. In response to the strengthening surface
high pressure over the Central Atlantic, low-level winds will veer
slightly to the east-southeast, pulling this deeper moisture field
across the CWA. This pattern will increase the potential for
organized shower and thunderstorm activity heading into the weekend,
with localized urban and small-stream flooding risks returning to
the forecast area.

&&

.AVIATION...
(18Z TAFS)
Issued at 156 PM AST Sat Aug 29 2026

Mainly VFR conditions expected early in the forecast period. VCSH
developing across W PR through 29/22Z. E winds at 15 to 20 kts
turning E to ENE and decreasing 8 to 12 kt overnight. ENE to NE
winds at 15-20 knots after 30/13Z. VCTS/SHRA increasing across the
USVI terminals after 29/23Z and PR terminals after 30/12Z as
a tropical wave moves into the region.

&&

.MARINE...
Issued at 156 PM AST Sat Aug 29 2026

The remnants of Tropical Storm Dolly, now a strong tropical wave,
are expected to move across the local area from tonight through
late Sunday. Squally weather, strong gusts, occasional lightning
and hazardous seas are expected across most waters. A small craft
advisory was issued for the Atlantic waters and the Anegada
Passage starting on Sunday.

&&

.BEACH FORECAST...
Issued at 156 PM AST Sat Aug 29 2026

The increase in winds and swells associated with the remnant of
Tropical Storm Dolly will allow the high rip current risk to
return across the northern, eastern and southeastern coastal areas
of PR as well as Vieques, Culebra and the US Virgin Islands.
Beachgoers are urged to remain out of the water due to the
expected strong currents and rough surf along unprotected
coastlines. In addition, thunderstorms with cloud-to- ground
lightning and gusty winds are expected during this period across
all islands and coastal waters.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Heat Advisory until 5 PM AST this afternoon for PRZ001>005-007-
     008-010>013.

     High Rip Current Risk from Sunday morning through Monday
     afternoon for PRZ001>003-005-008-012-013.

VI...Heat Advisory until 5 PM AST this afternoon for VIZ001-002.

     High Rip Current Risk from Sunday morning through Monday
     afternoon for VIZ001-002.

AM...Small Craft Advisory from 6 AM Sunday to noon AST Monday for
     AMZ711.

     Small Craft Advisory from 6 AM Sunday to 6 AM AST Monday for
     AMZ723.

&&

$$

SHORT TERM/MARINE/BEACH FORECAST...MMC/KML
LONG TERM...LIS
AVIATION...ICP

NWS SJU Office Area Forecast Discussion