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146
FXCA62 TJSJ 151818
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
218 PM AST Sun Nov 15 2026

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

.KEY MESSAGES...
Issued at 204 PM AST Sun Nov 15 2026

- Fair weather conditions will continue across the islands today.

- A slight increase in the frequency of morning showers is
  expected by Monday onward across the USVI and E PR, afternoon
  showers and isolated thunderstorm activity across W PR.

- The moderate risk will return along north- exposed beaches
  Monday night extending through midweek, as a weak northeasterly
  swell reaches the Atlantic waters.

&&

.Short Term(This evening through Tuesday)...
Issued at 204 PM AST Sun Nov 15 2026

Fair weather conditions prevailed across Puerto Rico and the U.S.
Virgin Islands this morning, with mostly sunny skies and no rainfall
activity observed across the islands.

For the rest of this afternoon, generally fair and warm weather
conditions will continue as a mid- to upper-level ridge maintains a
relatively stable atmospheric environment. The latest TJSJ 15/12Z
sounding indicated a notable drying trend compared to yesterday,
with precipitable water decreasing to 1.54 inches and relative
humidity between 850 and 500 mb dropping to around 31 percent.
Additionally, a pronounced inversion near 845 mb and a substantial
reduction in convective instability further support limited shower
development. Although daytime heating may promote some cloud
development, significant rainfall activity is not anticipated.
Meanwhile, above-normal temperatures will persist, particularly
across coastal and urban areas, supported by relatively warm low-
level temperatures and prevailing south to southeast winds.

By Monday and Tuesday, a gradual change in the weather pattern is
expected as the upper-level ridge weakens slightly and moisture
increases across the region. However, the most noticeable moisture
recovery is not anticipated until Monday afternoon into Tuesday,
with precipitable water values potentially increasing to around 1.6
to 1.8 inches, although some fluctuations are expected. Model
guidance also suggests a substantial increase in moisture between
850 and 700 mb, while the mid-levels remain relatively dry. Despite
the gradual weakening of the ridge, relatively warm 500 mb
temperatures and decreasing 700500 mb lapse rates will continue to
limit deeper convective development. Therefore, although shower
activity should gradually increase, widespread or organized
convection is not anticipated.

Under a prevailing easterly wind flow, passing showers will become
more frequent across windward sections of Puerto Rico and the U.S.
Virgin Islands, particularly during the overnight and morning hours,
followed by afternoon convection across the interior and western
portions of Puerto Rico. The increasing moisture could support
locally moderate to heavy showers where sufficient convergence
develops. However, given the relatively stable atmospheric
conditions, the overall flooding threat remains limited, with mainly
localized ponding of water on roads and poorly drained areas
possible. A limited excessive rainfall risk (Level 1 of 4) continues
through the short-term period.

&&

.Long Term(Wednesday through next Saturday)...
Issued at 204 PM AST Sun Nov 15 2026

A seasonal weather pattern is expected for the remainder of the
workweek, transitioning to more frequent passing showers and
variable conditions over the weekend as additional tropical moisture
filters into the region. An ESE flow will prevail through the second
half of the workweek as surface high pressure remains centered
across the central Atlantic, shifting more southeasterly over the
weekend as an induced surface low develops north northwest of the
local area. A mid- level ridge will remain in control through most
of the long- term period, maintaining generally stable conditions
aloft. However, trade wind perturbations induced by an upper low
well east of the Caribbean (near 40W to 50W) will bring pockets of
moisture from time to time, mainly confined to the lower levels of
the atmosphere. Precipitable water values will fluctuate between 1.6
to 1.8 inches, which is within seasonal levels for this time of the
year. Therefore, expect morning passing showers across windward
areas, followed by afternoon showers and isolated thunderstorms
across the interior and northwestern quadrant of Puerto Rico, as
well as potentially into portions of the San Juan metropolitan area.
Streamers are also likely to develop downwind from the USVI,
Vieques, and Culebra. While an upper-level trough will cross the
region from the west Thursday into Friday, dry mid- levels will
limit convective enhancement.

Over the weekend, as a more southeasterly flow establishes and the
surface low develops NNW of the region, additional moisture will
pool across the islands, with precipitable water values reaching 1.8
to 2.0 inches along with above seasonal levels of moisture in the
mid- level moisture. This setup will favor more frequent showers
across the regional waters and windward areas, including the USVI,
as well as more scattered afternoon showers and thunderstorms across
the interior and northwestern quadrant of Puerto Rico. The
persistent ESE to SE flow will maintain a daily heat risk,
particularly for sensitive individuals. Please continue to follow
recommendations from official health authorities.

&&

.AVIATION...
(18Z TAFS)
Issued at 204 PM AST Sun Nov 15 2026

VFR conds expected across all TAF sites thru the fcst period. No sig
wx impacts expected thru the period. SE winds at 10-15 kt with
occasional higher gusts, bcmg lgt/VRB overnight. E winds at 10-12 kt
expected Mon, with VCSH at TJSJ/TJPS and USVI terminals, and VCTS at
TJBQ late in the fcst period.

&&

.MARINE...
Issued at 204 PM AST Sun Nov 15 2026

A surface high pressure extending from the eastern to central
Atlantic will promote light to moderate southeasterly winds across
the regional waters through at least the beginning of the workweek.
Seas will generally range between 3 and 5 feet, occasionally
reaching up to 6 feet across the offshore waters and local passages.
By late Monday into the rest of the workweek, winds will become
easterly. However, marine conditions are expected to deteriorate by
midweek as a weak northeasterly swell, associated with a nearby low-
pressure system, reaches the Atlantic waters, resulting in
increasing seas of around 6 to 7 feet. Regardless, uncertainty
remains moderate and we urge mariners to continue to monitor our
forecast.

&&

.BEACH FORECAST...
Issued at 204 PM AST Sun Nov 15 2026

The moderate rip current risk is expected to gradually decrease
through Tuesday as winds and seas subside. However, an increasing
northeasterly swell is expected to reach the Atlantic waters by
Wednesday, potentially resulting in a return to moderate to high rip
current conditions, particularly across exposed beaches. A gradual
improvement in beach conditions is then expected beginning Thursday
as the swell subsides. Moderate uncertainty remains. Beachgoers
should continue to exercise caution, particularly along exposed
beaches. Life-threatening rip currents can still develop near
jetties, piers, and reefs, even where a low risk is forecast.
Although shower and thunderstorm activity is expected to remain
limited, isolated thunderstorms may develop near the western and
northwestern beaches of Puerto Rico during the afternoon hours.
Beachgoers should seek shelter immediately if thunder is heard and
remain weather aware.

&&

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

$$

SHORT TERM/AVIATION...CVB
LONG TERM....KML
MARINE/BEACH FORECAST...MMC

NWS SJU Office Area Forecast Discussion