160
FXCA62 TJSJ 131857
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
257 PM AST Thu Nov 13 2025

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

.KEY MESSAGES...
Issued at 249 PM AST Thu Nov 13 2025

* Dangerous coastal conditions through Friday due to hazardous
  breaking waves and life-threatening rip currents along the
  north-facing beaches of Puerto Rico and the northern US Virgin
  Islands.

* The US Virgin Islands can expect occasional showers each day,
  followed by afternoon activity downwind from the islands.

* Puerto Rico will experience afternoon showers and thunderstorms
  each day, increasing the potential for flooding rains during the
  weekend.

&&

.Short Term(This evening through Saturday)...
Issued at 249 PM AST Thu Nov 13 2025

Tonight through Saturday

The mid-to-upper-level trough approaching the islands weakened
the mid-to-upper-level ridge, resulting in scattered showers that
initially affected the local waters, then moved inland, crossing
the US Virgin Islands and impacting the windward locations of
Puerto Rico. Then, showers developed along the interior and
western PR around noon onward. Maximum temperatures ranged from
the mid-80s to the low 90s along coastal areas and the low 80s in
the mountains. Winds were predominantly from the east, with speeds
ranging from 5 to 15 mph, and higher gusts and variations in the
sea breeze.

The mid-to-upper-level ridge will slowly weaken as an upper-
level trough approaches from the northwest to the Northeast
Caribbean. This will increase the probability of afternoon
convection (50 percent to 70 percent) of one or two thunderstorms.
At the surface, a frontal boundary will linger north to northwest
of the islands, extending from the western Caribbean to the
Central Atlantic, weakening the steering winds, especially Friday
into the weekend.

According to the weather pattern outlined above, we anticipate an
increase in the potential for unstable weather patterns due to
the approaching upper-level trough and the proximity of a frontal
boundary, especially during the afternoon hours. However, a drier
air mass moving across the islands will result in a mixture of
sunshine and clouds on Friday, followed by a moderate to high
chance (50-70 percent) of afternoon convection, with a slight to
moderate chance of urban and small stream flooding. As the frontal
boundary lingers north of the islands and the trough amplifies
aloft, the potential for moderate to high showers and
thunderstorms will continue, especially on Saturday afternoon and
night.

&&

.Long Term(Sunday through next Wednesday)...
Issued at 249 PM AST Thu Nov 13 2025

A polar trough will escort a cold front near the area on Sunday,
increasing moisture across the region. Ahead of the front, high
pressure centered over the eastern Atlantic will drive the trade
winds from the south at speeds of only 3 to 4 kts. So far, the
global models only indicate precipitable water values near normal
levels, and also quite a large dew point depression in the mid
levels. This means that a widespread rainfall event is not expected.
However, some showers will reach the islands at times. Also, the
heaviest activity is expected to develop along the interior of
Puerto Rico due to local effects.

As the front dissipated north of the region, a short wave trough in
the upper levels will move into the region. This will cause mid-
levels temperatures to cool down, increasing instability aloft.
Moisture levels will not be impressive though, but should be enough
to see a few thunderstorms developing each afternoon along the
interior and western Puerto Rico. The risk of flooding is low at
this time, although isolated urban and small stream flooding cannot
be ruled out.

By the end of the week, another trough digs from the northeast. A
surface reflection of this trough will change the winds from the
northeast, at speeds of 10 to 15 mph. The islands are not expected
to be in the most favorable area for deep convection to develop, but
the frequency of passing showers could increase for portions of
northeast Puerto Rico, as well as for the Virgin Islands.

&&

.AVIATION...
(18Z TAFS)
Issued at 249 PM AST Thu Nov 13 2025

VFR conds should prevail across all TAF sites during the prd. San
Juan Streamer and aftn conv will promote VCTS across JSJ, JPS, and
JBQ from 13/18z, may reduce CIGs/VIS. Wind will become lighter from
the E- ENE by 1323z, btwn 5 - 6 kt, calmer at JPS. Winds should
increase once again btwn 8 - 11 kt by 14/13 - 14/14z.

&&

.MARINE...
Issued at 249 PM AST Thu Nov 13 2025

Dangerous marine conditions will continue due to a north-
northwesterly swell moving across the local Atlantic Waters and
Caribbean Passages. Conditions are expected to gradually improve
tomorrow. A frontal boundary will linger northwest of the islands,
extending from the western Caribbean into the Central Atlantic
through the workweek. Therefore, expect moderate to locally fresh
winds through today, becoming light to gentle from Friday into the
weekend, as a pre-frontal trough forms near the islands.

&&

.BEACH FORECAST...
Issued at 249 PM AST Thu Nov 13 2025

A long-period northwesterly swell will result in hazardous
breaking waves and life-threatening rip currents along the north-
facing beaches in PR and St Thomas, St John, and the Adjacent
Islands. Thus, a High Surf Advisory and the High Risk of Rip
Currents will continue through late Thursday night. Conditions
will slowly improve tomorrow as the wave energy dissipates,
leaving a moderate risk of rip currents for Friday.

&&

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

     High Surf Advisory until midnight AST tonight for PRZ001-002-005-
     008-010.

VI...High Rip Current Risk through late tonight for VIZ001.

AM...Small Craft Advisory until 6 AM AST Friday for AMZ711-712-716.

     Small Craft Advisory until 6 PM AST this evening for AMZ741-742.

&&

$$

DAY SHIFT...CAM/MNG
EVENING SHIFT...ICP/MRR