457
FXCA62 TJSJ 300706
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
306 AM AST Sun Aug 30 2026

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

.KEY MESSAGES...
Issued at 306 AM AST Sun Aug 30 2026

- An unsettled, wetter, and windier pattern is expected today
  into Monday as a strong tropical wave (Dolly`s remnants) moves
  across the region.

- The main weather hazards will be urban flooding, lightning, and
  gusty winds, starting early this morning across the U.S. Virgin
  Islands and gradually extending into Puerto Rico today and
  Monday. The potential for isolated flash flooding is lower but
  cannot be ruled out.

- Hazardous marine and coastal conditions are expected to develop
  today as winds and seas build. Small Craft Advisory and Rip
  Current Statement are in effect from this morning through at
  least Monday afternoon.

- Lingering moisture may bring additional showers into Tuesday,
  but heat is expected to return by Tuesday and remain the primary
  threat through the rest of the week.

&&

.Short Term(Today through Tuesday)...
Issued at 306 AM AST Sun Aug 30 2026

Radar and satellite imagery indicate partly cloudy skies across
the region, with passing showers dominating the overnight hours
this Sunday. Showers have been streaming inland from the
surrounding waters into northern and eastern sectors of Puerto
Rico. These showers have been quick-moving, with radar estimates
indicating maximum accumulations ranging from 0.10 to 0.25 inches
between midnight and 2 AM. Surface observations indicate northeast
winds of 10 to 15 mph, with occasional higher gusts. Overnight
temperatures across coastal and lower elevations of Puerto Rico
and the USVI have remained on the warm side, generally in the low
to mid 80s, while temperatures in higher elevations have ranged
from the upper 60s to mid 70s.

Looking at satellite-derived precipitable water data, the leading
edge of the moisture field associated with the approaching strong
tropical wave, Dollys remnants, is already over the Leeward
Islands and beginning to produce rainfall and lightning activity
near St. Croix. Latest model guidance suggests that moisture will
continue to increase from east to west throughout the day, with
showers and thunderstorms becoming more frequent first across the
U.S. Virgin Islands, then eastern Puerto Rico, and eventually
spreading across the remainder of Puerto Rico. Moisture is also
expected to increase through the mid to upper levels of the
atmosphere. Latest data indicate that relative humidity values in
the 700-500 mb & 850-700 mb layers will increase from below-normal
levels to a much more humid scenario, reaching two standard
deviations above normal and the 75th percentile, respectively.
Precipitable water values are expected to exceed 2 inches today
and remain above normal through the rest of the forecast period,
placing them within the above-normal range for this time of year
based on climatological data and maintaining an unstable weather
pattern.

As the strong tropical wave moves across the region today, winds
remain from the northeast before gradually shifting to the
southeast this afternoon and tonight, which will slightly shift
the focus of rainfall. Today, the greatest rainfall activity is
expected across eastern, interior, and southern areas, then across
interior and northwestern portions of Puerto Rico on Monday.

The main weather-related hazards that people could expect today
are urban and poor-drainage flooding, lightning, and gusty winds.
A limited flooding risk is expected across the U.S. Virgin Islands
today and Monday; meanwhile, an elevated flooding risk is
expected across most of Puerto Rico today and across the interior
and western areas of Puerto Rico on Monday. To put that in
context, an elevated risk means flooding in urban areas, roads,
small streams, and washes. There is a low chance of isolated flash
floods, but they cannot be ruled out. Unsettled conditions will
continue tonight through Monday as deep tropical moisture remains
across the region, with the same hazards continuing.

By Tuesday, the axis of the tropical wave is expected to be over
Hispaniola or slightly west, but trailing and remnant moisture
will remain across our region. Precipitable water values are
expected to remain above average, and combined with local effects
and diurnal heating, this will favor isolated morning showers
across eastern Puerto Rico, followed by afternoon showers and
thunderstorms across the interior and western sections. At the
same time, the potential for less cloud cover, southeast winds,
and temperatures at 925 mb around the 75th percentile will support
a return of hotter conditions on Tuesday. The combination of
available moisture and increasing heat will likely result in the
return of heat-related impacts, and heat-related products may
once again become necessary. At this time, we are highlighting a
significant heat threat returning on Tuesday.

Overall, periods of squally weather, particularly today and Monday,
will bring moderate to locally heavy rainfall in the short term.
If rainfall materializes as expected, it should provide some relief
from the ongoing drought conditions, although it is not expected
to end the drought. Lingering moisture will support additional showers
on Tuesday, however, warmer to hotter conditions are likely to return.

&&

.Long Term(Wednesday through Sunday)...
Issued at 306 AM AST Sun Aug 30 2026

A surface high pressure system over the western Atlantic will
maintain a south-southeasterly wind flow across the area. Moisture
fields trailing from the previous tropical wave will continue to
filter across the region, with elevated precipitable water (PWAT)
values inducing shower activity along eastern Puerto Rico during the
morning hours, followed by afternoon convective development across
interior and western sectors. By Thursday, conditions will change
slightly as the surface high pressure over the western Atlantic
strengthens, inducing a more easterly wind flow across the region.
Although moisture will remain near normal seasonal values, a mid-
level ridge will continue to build across the area, suppressing
widespread deep convection and limiting overall shower coverage. On
Friday, easterly winds will persist across the forecast area as a
drier air mass filters in, resulting in lower atmospheric moisture
levels and keeping shower activity minimal throughout the day. Heat
threat will be present for the first part of the long term mostly
due to the variable conditions and the presence of moisture,
resulting in heat indices between 100 to 111 degrees.

Late Thursday into Friday, atmospheric conditions will transition as
an upper-level trough over the western Atlantic continues to sink
southward into the region, while a moisture field associated with an
approaching tropical wave moves across the CWA. This evolving regime
will promote a more unsettled and variable weather pattern, creating
favorable conditions for increased shower and thunderstorm activity
across the local islands. In addition, positive cyclonic vorticity
advection ahead of the upper trough will enhance upper-level
dynamics and regional instability across the area. According to
global model guidance, both the GFS and ECMWF are in general
agreement regarding a surface perturbation moving across the CWA;
however, key discrepancies remain regarding moisture availability.
The ECMWF suggests a shorter wet period with less moisture
persisting into Sunday, whereas the GFS maintains a much wetter
solution, keeping an extensive moisture field anchored across the
forecast area through the end of the weekend. Therefore, residents
are urged to stay tuned as the forecast evolves near the end of the
upcoming workweek. The consensus so far remains that a wet and
unstable weather pattern is expected.

&&

.AVIATION...
(06Z TAFS)
Issued at 306 AM AST Sun Aug 30 2026

A strong tropical wave, the remnants of Tropical Storm Dolly will
move across the local area today. SHRA/TSRA is expected to gradually
increase through the early morning hours across the USVI terminals,
and by midday across the E PR terminals. Tempo MVFR to IFR conds
are possible across all terminals. Mtn tops obscd and BKN/OVC cigs
btw FL025-FL150 are expected, particularly during the afternoon
and evening hrs. Winds are expected to prevail from the NE at
10-20 kt with occasionally higher gusts thru 30/13z at TISX/TIST,
and thru 30/16-18z across the PR, winds will veer SSE after through
the rest of the period.

&&

.MARINE...
Issued at 306 AM AST Sun Aug 30 2026

The remnants of Tropical Storm Dolly, now a strong tropical wave,
will move across the region through late tonight. Squally
weather, strong gusts, and hazardous seas are expected across most
waters. Small craft advisory conditions are expected mainly for
the eastern coastal waters of Puerto Rico and the U.S. Virgin
Islands, the Atlantic waters, and the Anegada Passage through
early Monday. A weak surface high pressure building over the
Azores by midweek will promote moderate trades through the
workweek. The next tropical wave is expected to reach the local
area by the end of the workweek.

&&

.BEACH FORECAST...
Issued at 306 AM AST Sun Aug 30 2026

The remnants of Tropical Storm Dolly are expected to increase
winds and easterly swells, leading to a high risk of rip currents
across the northern, eastern, and southeastern beaches of Puerto
Rico, as well as Vieques, Culebra, and the U.S. Virgin Islands.
Beachgoers and inexperienced surfers are strongly advised to stay
out of the water due to the anticipated life-threatening rip
currents and rough surf along unprotected coastlines. Additionally,
thunderstorms with cloud-to-ground lightning and gusty winds are
expected today across all islands and coastal waters.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk from 6 AM AST this morning through Monday
     afternoon for PRZ001>003-005-008-012-013.

VI...High Rip Current Risk from 6 AM AST this morning through Monday
     afternoon for VIZ001-002.

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

     Small Craft Advisory from 6 PM this evening to 6 AM AST Monday
     for AMZ712-733.

     Small Craft Advisory from noon today to 6 AM AST Monday for
     AMZ716-726.

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

&&

$$

SHORT TERM...YZR
LONG TERM...LIS
MARINE/BEACH/AVIATION...DS