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938
FXCA62 TJSJ 290657
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
257 AM AST Thu Oct 29 2026

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

.KEY MESSAGES...
Issued at 227 AM AST Thu Oct 29 2026

* Another round of showers is expected this afternoon for the
  interior and western Puerto Rico, and portions of the San Juan
  metro area. Urban and small stream flooding may develop.

* Hot conditions will continue for Puerto Rico and the Virgin
  Islands. Users should look for shade and stay hydrated.

* Exceptionally high tides will continue today, with potential
  coastal flooding for vulnerable areas. The period of high tide
  is around noon.

* Unsettled weather conditions may develop on Saturday and Sunday.
  Users should stay tuned for further updates today and tomorrow.

&&

.Short Term(Today through Saturday)...
Issued at 227 AM AST Thu Oct 29 2026

A few showers moved into the vicinity of the Virgin Islands and
eastern Puerto Rico during the early morning hours. Otherwise,
skies were mostly clear, except across western Puerto Rico.
Temperatures cooled down to the low 80s in the Virgin Islands, the
upper 70s or low 80s across coastal areas in Puerto Rico, and into
the 60s for the Cordillera Central.

A low pressure area at the upper levels is currently located just
to the southeast of Puerto Rico, while high pressure at all levels
just to northeast of the islands maintain a southeasterly wind
flow. The steering flow will stay from this direction, at speeds
of 9 to 12 knots through at least Saturday. In the most recent
satellite-derived precipitable water imagery, plenty of moisture
is still evident over Hispaniola. Some of this moisture is still
reaching the local islands, with a slot of drier air just east of
the Lesser Antilles. Today, decent lapse rates, above normal
moisture and diurnal heating should trigger another round of
showers and thunderstorms for the interior and west of Puerto
Rico. Lines of showers could also reach the San Juan metropolitan
area. In these areas, the risk of urban and small stream flooding
will be medium, while frequent lightning is also anticipated.
Additional showers may also reach the Virgin Islands and eastern
Puerto Rico, where flooding is not a concern at this time.Tomorrow,
that slot of dry air will move in, limiting the potential for
rain activity.

There could be some changes in the forecast for Saturday,
especially late in the day. A deepening trough over the western
Caribbean will pull moisture into the region. Conditions aloft
could be favorable for an increase in showers and thunderstorms,
especially late in the day and in the nighttime. The confidence in
the forecast for this period is low at this time, since there are
some discrepancies in the global models regarding this rain
event. The users should stay tuned for any changes introduced in
the forecast.

Temperatures will remain warmer than normal, with a level of heat
that primarily affects individuals extremely sensitive, especially
when outdoors without effective cooling or adequate hydration.


&&

.Long Term(Sunday through Thursday)...
Issued at 227 AM AST Thu Oct 29 2026

Current model guidance suggests a humid pattern throughout the long
term period, favoring unsettled weather conditions and an increased
potential for rainfall. Precipitable water (PWAT) values are
expected to remain at or above 2 inches beginning Sunday, above
normal values based on November climatology (75th percentile).
Meanwhile, relative humidity in the 850 to 700 mb layer is expected
to remain near seasonal levels, while relative humidity in the 700
to 500 mb layer is forecast to remain above normal.

At the surface, high pressure over the Atlantic will promote
easterly to northeasterly winds at the start of the period,
gradually becoming southeasterly to southerly early next week.
Aloft, an upper level trough is expected to remain primarily west of
the region through the beginning of the period. However, some
uncertainty remains, as current model guidance suggests that the
trough will gradually move away from the region early next week. The
upper-level trough, along with embedded shortwave troughs, will
support mid-level temperatures near -6C through at least Monday,
potentially favoring cloud development and deeper convection
across the region. From Tuesday onward, guidance indicates a
gradual warming of mid-level temperatures, which could become
less favorable for deeper convection. By midweek, winds are
expected to become very light, potentially resulting in slow
moving showers and increasing the risk of localized flooding.
However, confidence in the overall rainfall coverage and intensity
remains limited, as upper level dynamics may become less
favorable. Afternoon convection will also depend on cloud cover
and the amount of daytime heating.

Overall, showers are expected during the overnight and morning hours
each day, particularly across the U.S. Virgin Islands and eastern to
southeastern Puerto Rico. During the afternoon, convection is
expected to develop across the interior, western, and northwestern
portions of Puerto Rico, with localized showers and streamers also
developing downwind of El Yunque and across the local islands on
most days. Periods of heavy rainfall could lead to urban and small
stream flooding. In addition, thunderstorms may produce frequent
lightning and gusty winds. Continue to monitor the forecast for
updates as model guidance becomes more consistent.

At this time, upper level dynamics appear more favorable for
enhanced convection on Sunday, at the beginning of the period. Later
in the week a mid-level ridge could help inhibit development. But
lighter winds could favor localized rainfall accumulation due to the
slow movement of showers. Nevertheless, cloud cover will remain an
important factor in determining the extent and intensity of
afternoon convection. Forecast uncertainty remains, as global models
continue to show some disagreement regarding the evolution of the
upper level pattern.&&

.AVIATION...
(06Z TAFS)
Issued at 227 AM AST Thu Oct 29 2026

SHRA and TSRA expected this afternoon (17-22Z) for the Cordillera
Central, and the vicinity of TJBQ and TJSJ. Periods of reduced
VIS and low ceilings can be expected. Passing SHRA expected for
the vicinity of USVI, but with little to no impact for terminals.
Winds will persist from SE at 9-12 kts, with stronger gusts and
sea breeze variations from 14-22Z.

&&

.MARINE...
Issued at 227 AM AST Thu Oct 29 2026

A surface high-pressure system over the central Atlantic will
maintain moderate  east to southeasterly winds across the regional
waters over the next few days. The long-period northerly swell that
has been affecting the local waters, will continue to gradually
subside today. Scattered showers and isolated t-storms will
continue to affect areas of the local waters and passages,
particularly over the waters near the northwestern quadrant of
Puerto Rico, potentially producing brief periods of reduced
visibility, locally gusty winds, and rougher seas. &&

.BEACH FORECAST...
Issued at 227 AM AST Thu Oct 29 2026

A high risk of rip currents (rip currents are likely in the surf
zone) will be in effect through 1 PM AST this afternoon along the
north-facing beaches of Puerto Rico and Culebra, becoming
moderate thereafter as the northerly swell energy continues to
decrease. Up to a moderate risk (rip currents are possible in the
surf zone) will persist across the USVI. Additionally, spring
tides, which contributed to elevated water levels during the past
few days, are expected to persist through at least tomorrow,
Friday. Consequently, even as the northerly swell subsides,
ongoing coastal effects may be heightened at high tide,
potentially resulting in localized flooding in susceptible, low-
lying shorelines. Beachgoers are strongly urged to stay out of the
water at beaches under a high risk of rip currents. Always
observe posted warning signs, flags, and guidance provided by
local authorities and lifeguards. Up to a moderate risk of rip
currents is expected to persist Friday and into the weekend.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk until 1 PM AST this afternoon for PRZ001-
     002-005-008-010-012.

VI...None.
AM...None.
&&

$$

SHORT TERM/AVIATION...ERG
LONG TERM....YZR
BEACH/MARINE...MRR

NWS SJU Office Area Forecast Discussion