316
FXCA62 TJSJ 061727
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
127 PM AST Tue Jan 6 2026

...New SHORT TERM, AVIATION...

.KEY MESSAGES...
Issued at 119 PM AST Tue Jan 6 2026

* A few passing showers will continue to reach Puerto Rico and the
  Virgin Islands in the upcoming days, mostly in the morning and
  evening hours. The flooding threat is slim to none.

* Temperatures will be seasonal, with lows in the low 60s for the
  high mountains in Puerto Rico, and the low 70s in coastal areas
  in both Puerto Rico and the Virgin Islands.

* Life-threatening rip currents are expected late Wednesday and
  Thursday along the northwest to northeast beaches of PR, with a
  moderate to high risk for the north and east-facing beaches in
  the USVI.

&&

.Short Term(This evening through Thursday)...
Issued at 119 PM AST Tue Jan 6 2026

The morning was variable along the north and east of Puerto Rico
and the Virgin Islands. Showers moved at times, affecting outdoor
activities, but they were not strong enough to cause any flooding.
Rainfall accumulations were minimal. Along southern Puerto Rico,
skies were mostly sunny.

Since early in the morning, mid-level water vapor imagery indicated
that a drier and cooler air mass has moved over the northeastern
Caribbean. At the low level, the TJSJ 06/12Z sounding did show
precipitable water values of 1.49 inches,which is near normal for
this time of year. Since then, values has gradually decreased to 1.2-
1.4 inches. Therefore, for the rest of Three King`s Day, weather
conditions should improve, but under a northeasterly breeze, some
showers may still stream along north and east Puerto Rico and also
over the Virgin Islands. The high resolution models also show that
showers are anticipated for the southwestern quadrant of Puerto
Rico, with enough accumulation to cause ponding of water on low-
lying areas. Aloft, a trough is crossing today, so isolated
lightning cannot be ruled out with the afternoon activity.

Then, for the middle of the workweek, a ridge will build in the mid
levels, maintaining any available moisture close to the surface.
Tomorrow, a surface trough will maintain the trade winds weak,
coming out of the northeast below 10 knots. This trough will cross
the region on Thursday, and winds will then shift from the east, but
still weak. In terms of impacts, Wednesday and Thursday look
similar. The morning and night hours will see brief rainfall
interruptions along the east and north of Puerto Rico and the Virgin
Islands. These showers will likely not cause flooding, but rather
will be a nuisance for outdoor activities. The afternoons will see
stronger showers along the southwest PR, with some ponding of water
along roads and low-lying areas at best.

In terms of temperatures, all indicators are near normal, meaning
mild to cool lows at night, mostly in the 60s for the mountains, and
the upper 60s to low 70s for coastal areas. Highs will still climb
to the low and mid-80s each afternoon.


&&

.Long Term(Friday through next Monday).../prev discussion/
Issued at 119 PM AST Tue Jan 6 2026

A surface high pressure moving from the western Atlantic into the
central Atlantic will promote moderate to locally fresh east to
northeasterly trades during the long term period. A weak induced
surface trough northeast of the region will bring at times patches
of low-level moisture over the islands, particularly on Friday and
Saturday. During the second half of the forecast period, at the
upper levels, a ridge over the southwestern Atlantic and a
developing TUTT-low from the north central Atlantic will promote
drier air aloft and more stable conditions in general. Therefore,
showers that form through the period are not expected to produce
heavy rainfall or grow into thunderstorms. These showers will be
mainly driven by the increasing northeasterly trades, favoring an
advective pattern at night, with showers moving at times across
the USVI and along the east and north sections of PR. Shallow
afternoon convection is expected over the Cordillera and the
southern sections of PR, but the flood risk will remain low as
rainfall accumulations are not expected to exceed an inch of rain
per day.

By early next week, global models now have the strong TUTT-low
and induced surface trough a little farther away of the islands.
This solution now suggest a drier weather trend than previously
expected, with the GFS indicating a minimum in precipitable water
content of 1.00-1.25 inches on Monday and Tuesday.

&&

.AVIATION...
(18Z TAFS)
Issued at 119 PM AST Tue Jan 6 2026

Mainly VFR conditions expected to prevail through the forecast
period. SHRA will continue to stream across the Atlantic and
Caribbean waters, but impacts to operations, if any, should be
limited. VCTS is expected for TJPS before 21z, with brief periods of
reduced VIS and low ceilings possible. Winds are from the NE at 7-12
kts, gusting up to 20 knots. Winds will slow down after 22Z, before
picking back up at 07/13-14Z.

&&


.MARINE...
Issued at 119 PM AST Tue Jan 6 2026/prev discussion/

Light to moderate northerly winds will continue today as a frontal
boundary moves across the region. Showers and isolated thunderstorms
are expected to continue through most of the morning hours. A long
period northerly swell is expected to arrive on Wednesday, building
seas up to 6 feet, particularly across the Atlantic waters and Caribbean
Passages. A surface high pressure over the western Atlantic and weak
induced surface troughs northeast of the region will promote moderate
east to northeast trades for the rest of the period.

&&


.BEACH FORECAST...
Issued at 119 PM AST Tue Jan 6 2026/prev discussion/

A long period northerly swell will cause rough surf and life-
threatening rip currents across the north-facing beaches of
Puerto Rico, particularly on Wednesday. Elsewhere, the risk of rip
currents will be moderate, except along the southern beaches of
the islands where the risk will remain low throughout the week.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
AM...None.
&&

$$

SHORT TERM/AVIATION...ERG
PUBLIC DESK....RVT

NWS SJU Office Area Forecast Discussion