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302
FXCA62 TJSJ 091904
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
304 PM AST Mon Nov 9 2026

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

.KEY MESSAGES...
Issued at 304 PM AST Mon Nov 9 2026

- Ongoing shower and thunderstorm activity is increasing the
  chance for urban and small-stream flooding and frequent
  lightning and gusty wind conditions across the interior and
  north central of Puerto Rico. Landslide and flash flooding
  cannot be ruled out due to saturated soils.

- Slow moving showers induced by the islands continue to affect
  portions of the US Virgin Islands, Vieques and Culebra.

- Northeasterly swells will maintain a high rip current risk for
  the north- facing beaches of Puerto Rico and the US. Virgin and
  Culebra through Tuesday afternoon.

- Conditions are expected to become more seasonal from mid-week
  onwards with afternoon shower activity focusing on the northern
  interior and northwestern Puerto Rico during the afternoons.

&&

.Short Term(This evening through Wednesday)...
Issued at 304 PM AST Mon Nov 9 2026

The forecast remains predominantly on track. The CWA is positioned
within a col region with calm SSE winds of less than 10 knots as a
surface low-pressure system located to the NE of the US Virgin
Islands moves further into the central Atlantic. This windflow
continues to advect tropical moisture inland. Thus, the islands are
currently embedded within a pool of tropical moisture with a
relatively humid vertical profile and precipitable water (PWAT)
values above average levels for the season (1.8-2.2 inches). The
variable winds and available moisture will lead to showers and
thunderstorms across northern interior, northwestern and
northeastern Puerto Rico during the afternoon. As the conditions
linger across the region, a similar pattern is expected Tuesday with
the focus of the activity being across the northern interior of
Puerto Rico. The US Virgin Islands will continue to see calmer
conditions with scattered showers possible each day. Thus, flooding
in urban areas, roads, small streams and washes along with low
chance of isolated floods is an expected risk. Some regions within
the CWA have reported around 4 inches of rain over the past 72
hours. Given that some of the soils may be either saturated or close
to saturation landslides cannot be ruled out especially over areas
that have received frequent downpours over the last few days.
Additionally, some of these heavy showers are associated with
strong thunderstorms that could also result in areas with frequent
lightning and gusty wind conditions.

A more amenable period will begin on Wednesday, as an airmass with
reduce moisture (PWAT below 1.8 inches) begins to move across the
region. The wind will become more SE but will remain calm. Thus,
any shower and thunderstorm activity that does develop will be
primarily focused on the northern interior, and northwestern
portions of Puerto Rico.

The available moisture, low surface winds, and 925 mb temperatures
above 22 degrees Celsius, will lead to level of heat that may affect
those individuals extremely 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.

&&

.Long Term(Thursday through Monday)...
Issued at 231 AM AST Mon Nov 9 2026

The long-term forecast remains on track, with weather conditions
becoming more stable by late this weekend. A surface high pressure
building over the Central Atlantic should increase local pressure
gradient, with strengthening winds from the S-SE. The latest model
guidance suggests abundant tropical moisture moving into the region
early Thursday and Friday, with PWAT values up to 1.75 inches,
typical for this time of the year. However, moisture content should
gradually diminish as a drier air mass filters in the mid-levels on
Saturday and Sunday, limiting deep convection. In the mid and upper
levels, the nearby short-wave troughs should introduce troughiness
across the area on Thursday and Friday, with slightly cool mid-level
temperatures (around -6 C), allowing cloud growth. However, a
building ridge northeast of the CWA should dominate the weather
pattern in the weekend, warming mid-level temperatures (up to -4 and
-5 C), leading to subsidence and stability aloft. Additionally, the
Galvez-Davison Index suggest the potential for thunderstorms across
the local area mainly on Thursday and Friday, while Saturday and
Sunday should become more shallow in the afternoons. The latest
model solutions suggest a frontal boundary approaching the northern
Caribbean by Sunday, though the best area of deep convection should
remain outside the CWA. Overall, showers are likely to move during
the night and morning hours, particularly across windward sections
of the islands, followed by afternoon convection, particularly
across interior and northwestern/northern Puerto Rico. As mentioned
above, the best opportunity for deeper convection is Thursday and
Friday, with mainly ponding of water over roadways and poorly
drained areas, along with isolated urban and small stream flooding.

Under a S-SE wind flow, the latest model guidance suggest warmer
than normal 925 mb temperatures across the CWA. With the available
moisture, heat indices could easily exceed 100 F, particularly
across urban and low-lying areas of the islands during the peak
hours of the day. Therefore, the heat threat will remain limited to
elevated.

&&

.AVIATION...
(18Z TAFS)
Issued at 304 PM AST Mon Nov 9 2026

SHRA/TSRA will continue to develop across interior PR and near the
USVI through approximately 09/23Z. Mtn obsc and frequent lightning
are likely. Brief MVFR to IFR conditions are possible within this
activity due to reduced VIS and low CIGs. Surface winds will range
from 510 kt, primarily influenced by sea breezes with a weak ESE
background flow. VFR conditions are expected to prevail after 09/23Z
as convection diminishes. Another round of aft convection possible
btwn 10/16-23z, ESE winds around 10kt with sea breeze aft 10/13z.

&&

.MARINE...
Issued at 304 PM AST Mon Nov 9 2026

Energy from a NE swell will continue to maintain seas at 4-5 feet
across the northern offshore waters today as a surface low-pressure
system continues to move eastward across the Atlantic Ocean. With a
building high pressure system over the west Atlantic, the islands
are currently located in a col region with a light-to-gentle SSE
breeze that will persist until Wednesday. A moderate-to-strong SSE
breeze will prevail from Wednesday into Friday. Waves will range
between 4-5 feet across northern offshore waters and between 2-5
along the southern offshore waters. Showers and isolated
thunderstorms may produce locally higher winds and seas.

&&

.BEACH FORECAST...
Issued at 304 PM AST Mon Nov 9 2026

A northeasterly swell will continue to impact the Atlantic waters
and local passages, producing breaking waves of 5 to 7 feet along
the north-facing beaches of Puerto Rico and Culebra. This means life-
threatening rip currents are likely in the surf zones. Pulses from
this swell are likely to continue until Tuesday afternoon.

As a result, a high risk of rip currents was extended through at
least Tuesday afternoon along north-facing beaches of Puerto Rico,
local passages and Culebra. Also, a moderate risk of rip currents
persists along the north facing beaches of Vieques and the U.S.
Virgin Islands. Beachgoers should remain cautious, as rip currents
are possible. Continue to monitor the forecast for updates.

Thunderstorms pose another beach hazard, particularly during the
afternoon hours. If thunder is heard, seek shelter immediately.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk through Tuesday afternoon for PRZ001-002-
     005-008-010-012.

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

$$

KEY MESSAGES...RVM/JCP
SHORT TERM/MARINE...RVM
LONG TERM...MNG
AVIATION...CAM
BEACH...JCP

NWS SJU Office Area Forecast Discussion