137
FXCA62 TJSJ 040706
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
306 AM AST Sat Oct 4 2025

.KEY MESSAGES...

* A strong, long-period northerly swell will continue to produce
  hazardous marine and beach conditions across the islands through
  at least early next week. A Coastal Flood Advisory, Small Craft
  Advisories, Rip Current Statements, and High Surf Advisories
  remain in effect.

* Showers and thunderstorm activity is expected this afternoon
  over portions of central and northwestern Puerto Rico, enhancing
  the flooding and lightning threat across the area. If thunder
  roars, stay indoors.

* Across the U.S. Virgin Islands, passing showers will move
  occasionally over the region through the afternoon hours.

&&

.SHORT TERM...Today through Monday...

Conditions were mostly tranquil during the night hours. Some showers
manage to form in the vicinity of the Virgin Islands and eastern
Puerto Rico, but accumulation over land was very little. Skies were
mostly clear.

The trade winds are still weak, with a steering flow now shifting
from the southeast and at 4 to 8 kts. The winds will increase just a
bit on Sunday and Monday, but still around 8 to 11 kts. At the upper
levels, an upper level low will maintain some instability in the
area, and this feature will linger into early in the workweek.
Moisture is a little below normal today, but it is expected to
increase toward more normal values on Sunday, and even a little more
on Monday due to an approaching tropical wave. In general, the
pattern will favor afternoon showers along the Cordillera Central
and western Puerto Rico today and Monday. Showers could also stream
from El Yunque toward the San Juan metro area. The risk of flooding
will be elevated with a medium chance of these areas experiencing
urban and small stream flooding. Some lightning strikes will be
possible too. In the Virgin Islands, as well as some sections of
eastern Puerto Rico, passing showers will be on the increase by late
Sunday and Monday. While flooding is not really anticipated, ponding
of water and wet roads can still be expected.

.LONG TERM...Tuesday through Saturday...

The forecast period starts with a wet and unstable pattern due to
the influence of an upper-level low over the region. By Tuesday, the
convergence of this low with an approaching weak tropical wave is
expected to enhance the potential of convective activity,
specifically showers and thunderstorms, across the U.S. Virgin
Islands and Puerto Rico. High atmospheric moisture will sustain the
showers and thunderstorm activity through Tuesday evening, with
PWAT content near-to-above-normal (2.00 to 2.25 inches). A
noticeable change is anticipated for Wednesday, as a departing
upper-level low allows drier air to move in, causing PWAT values
to fall to the 1.50 to 1.75 inch range. Looking ahead to Thursday,
local conditions will become dependent on the evolution of a
tropical wave currently near the coast of Africa.

Regarding the potential system, the National Hurricane Center (NHC)
has given this wave a medium formation chance (50%) over the next 7
days. Although the latest model guidance indicate increasing
moisture by the weekend, the system`s eventual trajectory and
intensity remain highly uncertain. All residents and visitors must
continue to track the progress of this system as it moves westwards
over the Atlantic Ocean.

&&

.AVIATION...
(06Z TAFS)

Mainly VFR conditions expected to prevail through the forecast
period. After 17-19Z, SHRA and TSRA are expected to develop along
the Cordillera Central. These showers should reach the PR terminals,
causing periods of reduced VIS and low ceilings. VCSH are expected
for VI terminals, but impacts to operations are expected to be
minimal. Winds are light, out of the E to ESE at 2-8 kts.

&&

.MARINE...

A col near the region will promote a light to gentle variable wind
flow across the islands for the next few days. A long-period north
to northwesterly swell will spread across the local Atlantic waters
and passages through early next week, deteriorating marine and
coastal conditions through early next week. A tropical wave will
approach the region by Monday, increasing the frequency of
showers.

&&

.BEACH FORECAST...

A strong, long-period northerly swell will continue to produce
hazardous beach conditions through at least Monday night along the
Atlantic exposed beaches, including from western to northeastern
Puerto Rico, Culebra, Vieques, and the U.S. Virgin Islands. As a
result, there is a high risk of life-threatening rip currents in
the aforementioned areas.

A Coastal Flood Advisory is in effect for all the Atlantic exposed
beaches of the islands through Saturday evening. In addition, a
High Surf Advisory is in effect for these areas through Monday
morning. Please refer to our Coastal Hazard Message (CFWSJU) for
additional details. Residents and visitors are urged to monitor
the beach forecast and follow the beach flag warning system.
Beachgoers, do not risk your life, it`s better to stay out of the
water throughout the upcoming weekend!

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Coastal Flood Advisory until 6 PM AST this evening for PRZ001-
     002-005-008.

     High Rip Current Risk through Tuesday afternoon for PRZ001-002-
     005-008-010-012-013.

     High Surf Advisory until 6 AM AST Monday for PRZ001-002-005-008-
     010-012.

     High Rip Current Risk through this afternoon for PRZ011.

VI...High Rip Current Risk through Tuesday afternoon for VIZ001.

     High Surf Advisory until 6 AM AST Monday for VIZ001.

     High Rip Current Risk from 6 AM AST this morning through Tuesday
     afternoon for VIZ002.

AM...Small Craft Advisory until 6 PM AST Monday for AMZ711-712-716-
     723-741-742.

     Small Craft Advisory until midnight AST tonight for AMZ745.

&&

$$

ERG/GRS