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378
FXCA62 TJSJ 070816 CCA
AFDSJU

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
416 AM AST Sat Nov 7 2026

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

.KEY MESSAGES...
Issued at 331 AM AST Sat Nov 7 2026

- Slow-moving afternoon showers will elevate the threat
  for urban and small-stream flooding, localized flash flooding
  and mudslides across portions of the interior to northeastern PR
  through Sunday.

- Showery conditions expected to continue over the U.S. Virgin
  Islands today, where minor urban flooding is possible.

- There is a high risk of life threatening rip currents across the
  north-facing beaches of Puerto Rico through the weekend with a
  peak on Sunday.

- By mid-week next week a stable weather pattern is expected to
  prevail across the region.

&&

.Short Term(Today through Monday)...
Issued at 331 AM AST Sat Nov 7 2026

A weak synoptic pressure gradient will dominate the northeastern
Caribbean through the short-term period as a broad surface low
tracks across the western to central Atlantic well north of the
region. Aloft, mid-to-upper level ridging south of the region
combined with weak troughing to the northeast will maintain light
west-southwesterly flow and low vertical wind shear. In this
nearly stationary environment, low-level steering winds will
generally range from 5 to 10 knots. Meanwhile, recent satellite
imagery and regional moisture analyses show a pronounced plume of
deep tropical moisture surrounding Puerto Rico and the U.S. Virgin
Islands. Forecast soundings show precipitable water content
peaking between 2.00 and 2.25 inches through early Sunday,
exceeding the 75th percentile of climatology. This high moisture
profile, coupled with 850-700 mb relative humidity around 80
percent and high 850 mb equivalent potential temperatures, will
provide an unstable, saturated column highly favorable for
convective development.

Given the weak steering flow, convective development through
Sunday will be governed predominantly by diurnal heating, local
sea breezes, and orographic lift. High-res guidance and regional
precipitation forecasts highlight showers and thunderstorms
expanding across the interior, north, and east of PR during the
afternoon hours, while scattered showers cross the USVI and
regional waters, with a higher probability of heavy showers in and
around St. Croix. Ensemble rainfall guidance indicates 24-hour
accumulations ranging from 1 to 1.50 inches over north-central and
eastern Puerto Rico, with localized swaths exceeding 2 inches
where persistent or training convection materializes. Because of
the slow storm motion, rainfall duration over some areas will be
prolonged. Therefore, the primary weather hazards will be
localized urban and small-stream flooding, rapid rises along small
rivers, ponding of water in poorly drained urban areas, and
isolated mudslides along steep terrain.

A transition toward a drier air mass will take place on Monday as
the deepest moisture axis shifts eastward and mid-level dry air
filters into the region. Relative humidity in the 700-500 mb
layer is expected to fall near 50 percent, while precipitable
water values decrease back toward seasonal normals between 1.60
and 1.80 inches. Shower activity across the USVI will become more
isolated, while afternoon showers and thunderstorms across PR
become more localized, concentrating mainly over the interior and
eastern municipalities where sea breeze convergence focuses.

&&

.Long Term(Tuesday through Saturday)...
Issued at 331 AM AST Sat Nov 7 2026

As the low pressure north of the region moves further into the
central Atlantic and the surface high pressure builds to the NW of
the region, winds should become more S-SSE across the Islands
throughout the long-term period. Calm winds will prevail into mid-
week with conditions becoming locally breezy by Friday. The
beginning of the week will be characterized by variable conditions
as with average precipitable water (PWAT) and abundant moisture in
the low and mid levels. Low steering winds combined with local
effects, daytime heating, and sea breeze convergence will lead to
rainfall activity with a focus on the interior and northern portions
of Puerto Rico each afternoon. Shower activity from streamers and
advective showers will should also move during the morning and over
night hours across the US Virgin Islands, SE Puerto Rico and the San
Juan metro area each day as well. During the second part of the next
workweek, a mid-level ridge will move into the vicinity of the
region to the east of the islands, warming the mid-temperatures,
leading to sinking air, and stability aloft. This will act as a
limiting factor for the development of deep convective cells by the
end of the workweek. Another limiting factor for the development of
widespread convection will be the lack of available moisture in the
mid-levels.

Thus, the potential for excessive rainfall and lighting associated
risks will decrease as the week progresses. The focus of the
activity will be predominantly the interior and northern portions of
Puerto Rico during the afternoons. This level of risk may lead to
ponding of water over roadways and poorly drained areas, without
ruling out isolated urban flooding. The available moisture, above
average low tropospheric temperatures, and low surface winds will
lead to a level of heat that may affect those individuals sensitive
to heat especially when outdoors without effective cooling and/or
adequate hydration. Individuals are invited to continue monitoring
the weather conditions as they evolve.


&&

.AVIATION...
(06Z TAFS)
Issued at 331 AM AST Sat Nov 7 2026

VFR early in the fcst period, with -RA possible at TISX and mostly
VCSH across all terminals. However, by noon, sct convection
expected to develop over the eastern interior of PR and in and
around the U.S. Virgin Islands. This may cause tempo MVFR conds at
TJSJ/TISX/TIST thru 07/23z. Mostly VCTS at TJPS thru this period.
Winds will prevail from the west to southwest btw 5 and 15 kt,
with the highest wind speeds across the USVI terminals. A weak
WNW sea breeze is expected at TJSJ.

&&

.MARINE...
Issued at 331 AM AST Sat Nov 7 2026

Light to locally moderate west to southwesterly winds will dominate
the northeastern Caribbean through the weekend as a broad surface
low tracks across the western to central Atlantic, well north of the
region. A long period northeasterly swell from this low will
continue to spread across the Atlantic waters through early Monday,
with most of the swell energy expected from tonight into Sunday. This
may result in building seas of around 5 to 6 feet across the Atlantic
waters and passages. Shower and thunderstorm activity expected mainly
across the eastern waters and the Anegada Passage. Gusty winds,
reduced visibility, sudden waterspouts, and frequent lightning are
possible with this activity. Light trade winds return early in the
workweek.

&&

.BEACH FORECAST...
Issued at 331 AM AST Sat Nov 7 2026

A long-period (~11 seconds) northeasterly swell will continue to
gradually spread across the Atlantic waters, resulting in a high
risk of rip currents through the weekend, mainly affecting the
north- facing beaches of Puerto Rico and Culebra. From this
afternoon through Sunday, building seas will increase the
likelihood of life-threatening rip currents. As a result, a Rip
Current Statement is in effect from today through at least Sunday.
Across the U.S. Virgin Islands, a moderate risk of rip currents
is expected, while a low risk will prevail along the southern
beaches of Puerto Rico. Caution is always recommended as life-
threatening rip currents remain possible is the surf zones.
Additionally, isolated thunderstorms and showers may affect
beachgoers, especially during the afternoons. If you hear thunder,
seek shelter immediately.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk through Sunday afternoon for PRZ001-002-
     005-008-012.

VI...None.e SSW to WSW at 5 to 15
knots, accompanied by local sea breeze variations and higher gusts.
AM...None.
&&

$$

AVIATION/SHORT TERM...DSR
LONG TERM....RVM/MNG
MARINE/BEACH...YZR/DSR

NWS SJU Office Area Forecast Discussion