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443
FXCA62 TJSJ 161845
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
245 PM AST Thu Apr 16 2026

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

.KEY MESSAGES...
Updated at 245 PM AST Thu Apr 16 2026

* Unsettled weather will persist through Friday, with showers and
  isolated thunderstorms, especially in the afternoon. Localized
  urban and small stream flooding will remain possible.

* A moderate risk of rip currents will continue across the beaches
  in PR and the USVI, particularly along northern and eastern
  exposures. Beachgoers should exercise caution.

* Conditions will gradually improve by Saturday, leading to a
  more typical seasonal pattern with strong afternoon convection
  across western PR.

* The USVI will be affected by night and morning passing showers,
  which could result in brief moderate to locally heavy rain
  across portions of the islands.

&&

.Short Term(This evening through Saturday)...
Issued at 245 PM AST Thu Apr 16 2026

The surrounding waters of St. Croix and areas downwind of St.
Thomas experienced an active morning, with thunderstorms moving
across the local waters. Across eastern Puerto Rico, heavy
rainfall led to urban and small stream flooding, particularly near
Yabucoa, San Lorenzo, Las Piedras, Patillas, and Maunabo, where
rainfall totals ranged from 2 to 6 inches. The Guayanes River
also exceeded bankfull, as indicated by USGS observations. In the
afternoon, a second round of thunderstorms further aggravated
flooding, prompting a Flash Flood Warning for Juncos, Las Piedras,
and San Lorenzo. Winds remained from the east-southeast at 10 to
20 mph.

A mid- to upper-level trough, combined with above-normal
moisture, will maintain an unstable, wet pattern from tonight
through at least late Friday night. Soils are already saturated,
and rivers are elevated; therefore, any additional periods of
heavy rainfall will quickly lead to urban flooding, small stream
flooding, river flooding, and flash flooding.

Periods of showers and thunderstorms will occur in pulses rather
than continuously. For example, activity is expected this
afternoon across much of Puerto Rico, while the USVI may see
variable cloudiness with limited rainfall. Another round of
showers and thunderstorms is possible this evening, particularly
across eastern Puerto Rico and possibly the USVI, followed by
additional activity early Friday morning. By Friday afternoon,
convection is expected to redevelop across the interior and
western Puerto Rico.

Although the USVI will remain under the influence of high
moisture and the upper-level trough, confidence remains low
regarding rainfall coverage and intensity.

A more typical pattern is expected on Saturday; however, another
round of strong afternoon thunderstorms will be possible across
the interior, western Puerto Rico, and the San Juan metro area.
Passing showers will also remain possible across windward areas of
Puerto Rico and the USVI.

Residents and visitors are urged to remain alert and monitor
official forecasts, advisories, and warnings as conditions evolve.

&&

.LONG TERM(Sunday through Thursday)...
Issued at 250 AM AST Thu Apr 16 2026

The latest model guidance continues to suggest an influx of
relatively drier air as a surface high pressure system dominates the
central Atlantic and a mid-level ridge establishes west of the
region. During the first half of the period, precipitable water
(PWAT) values will drop to seasonal normals of 1.25 to 1.50 inches.
Under the influence of the surface high, light to moderate easterly
winds will prevail through mid-week, shifting from the southeast
late Wednesday as another building high pressure located over the
western Atlantic begins to migrate toward the central Atlantic.

Overall weather conditions are expected to remain seasonal. Passing
showers are likely over the windward portions of Puerto Rico and the
U.S. Virgin Islands, followed by afternoon convective activity
across the central mountain range and western Puerto Rico, driven by
daytime heating and local effects. Due to this anticipated activity,
showers and isolated thunderstorms will likely persist from the
early afternoon into the evening.

Because of previous rainfall, soil saturation, and elevated river
levels, the potential for flooding remains an active concern.
Additionally, temperatures at the 500 mb level are projected to drop
to -8C, increasing instability aloft and enhancing the potential
for afternoon thunderstorms. Surface temperatures are expected to
trend within seasonal values throughout the forecast period.

&&

.AVIATION...
(18Z TAFS)
Issued at 245 PM AST Thu Apr 16 2026

Generally VFR conds across most sites, however periods of
MVFR/IFR conditions are possible across TJBQ/TJSJ from 16/18-23Z
with TSRA, reduced vis, and low cigs. Additional periods of VCSH
during the overnight across USVI TAF sites and TJSJ. Winds from
the E to SE around 10 to 15 kts with higher gusts through 16/23Z.
Variable winds afterward and increasing again around 17/13Z.

&&

.MARINE...
Issued at 245 PM AST Thu Apr 16 2026

A mid- to upper-level trough will maintain an unstable weather
pattern across the regional waters, supporting periods of strong
thunderstorms through at least Friday night. These storms may
produce locally higher winds, frequent lightning, and reduced
visibility. At the surface, high pressure over the western to
central Atlantic will promote moderate to locally fresh east to
southeast winds, resulting in moderate to choppy seas through at
least early next week. In addition, a small northeasterly swell
will continue to propagate across the Atlantic waters and
Caribbean passages through early next week, contributing to
hazardous marine conditions at times.

&&

.BEACH FORECAST...
Issued at 245 PM AST Thu Apr 16 2026

Beachgoers can expect a moderate risk of rip currents through
much of the forecast period, especially along north- and east-
facing beaches of Puerto Rico and the U.S. Virgin Islands. Looking
ahead, another long-period northerly swell may arrive by early
next week, potentially worsening beach conditions. In addition,
beachgoers should remain alert for afternoon showers and isolated
thunderstorms, particularly across western and northern Puerto
Rico. These storms may produce gusty winds and frequent lightning.

&&

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

$$

SHORT TERM/MARINE/BEACH...CAM
LONG TERM...GRS
AVIATION...YZR

NWS SJU Office Area Forecast Discussion