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599
FXCA62 TJSJ 171814
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
214 PM AST Fri Apr 17 2026

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

.KEY MESSAGES...
Updated at 214 PM AST Fri Apr 17 2026

* A wet pattern will persist through much of the forecast period,
  which, combined with local effects, will promote showers and
  thunderstorms producing flooding rains across portions of PR
  each day.

* Showers embedded in the trade will move across the USVI each
  day, resulting in occasional ponding of water in roads and
  poorly drained areas, and isolated thunderstorms downwind of the
  islands each afternoon.

* Beachgoers can expect a moderate risk of rip currents along
  north and east-facing beaches throughout the forecast period in
  PR and the USVI.

&&

.Short Term(This evening through Sunday)...
Issued at 214 PM AST Fri Apr 17 2026

In general, we observed calm weather across the USVI and PR in
the morning. However, we detected some thunderstorms across the
regional waters. Then, rainfall began to affect the USVI, but this
activity was brief. In PR, thunderstorms formed downwind from El
Yunque into the San Juan Metro Area. Then, the activity moved
across western PR, where Flash Flood Warnings were issued. The
winds were mainly from the east-southeast at 10 to 20 mph, with
sea-breeze variations. Maximum temperatures were in the mid- to
upper 80s.

A lingering mid- to upper-level trough, along with above-normal
moisture, will create an unstable and wet weather pattern in the
short term. Soils are already saturated, and river levels are
elevated; therefore, any additional heavy rainfall could quickly
result in 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 western and interior Puerto Rico, while the USVI
may see variable cloudiness with occasional showers. The residents
in western PR are encouraged to exercise caution, as between 1
and 3 inches of rain with locally higher amounts have fallen at
the time of this discussion, and rivers will respond later this
afternoon or evening, with minor flooding likely to worsen later
this afternoon, especially across the areas under warning. Another
round of showers and thunderstorms is possible this evening,
particularly across eastern Puerto Rico and possibly the USVI,
followed by additional activity early Saturday morning.

On Saturday and Sunday, a similar convective pattern will form,
especially in the afternoon across the interior and western PR,
with additional rounds during the evening and morning hours.
Although the USVI will remain under the influence of high moisture
and the upper-level trough, confidence remains low regarding
rainfall coverage and intensity.

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

&&

.LONG TERM(Monday through Friday)...
Issued at 250 AM AST Fri Apr 17 2026

The forecast remains on track with no significant changes from
the previous discussion. As the influence of the upper-level
trough weakens and exits the northeastern Caribbean, drier and
more stable conditions are expected to return. A mid-level ridge
will build over the area, bringing a stable air mass aloft. At the
surface, a dominant high pressure system over the central
Atlantic will maintain light to moderate easterly winds through
mid-week. During the first half of the period, precipitable water
(PWAT) values will drop to seasonal normals of approximately 1.50
inches and are expected to remain within that range for the rest
of the workweek.

Local conditions will stay seasonal, with occasional showers moving
into the eastern portions of Puerto Rico, Vieques, Culebra, and the
U.S. Virgin Islands during the morning hours. This will be followed
by afternoon convective activity across the interior and western
portions of Puerto Rico. This afternoon activity could result in
moderate to heavy rainfall and isolated thunderstorms due to the
combination of available moisture, daytime heating, and local
effects. Temperatures at 500 mb are expected to remain within
seasonal values of -6C to -8C; therefore, a thunderstorm or two
cannot be ruled out. Due to previous rainfall, soil saturation, and
elevated river levels, the potential for flooding persists.
Temperatures at 925 mb will remain seasonal through most of the
period, with highs in the low to mid-80s across coastal and urban
areas and the upper 70s to low 80s in the higher mountains.

&&

.AVIATION...
(18Z TAFS)
Issued at 214 PM AST Fri Apr 17 2026

Mainly VFR conditions are expected across TAF sites with the
exception of SHRA & TSRA from 17/18Z thru 17/22Z that could
result in intermittent MVFR to brief IFR conds across TJBQ.
E winds at around 10 to 15 kts with gusts around 18 to 25 kts and
sea breeze variations, becoming lighter overnight and increasing
again around 18/13Z onward along with SHRA/TSRA aft 18/16Z.

&&

.MARINE...
Issued at 214 PM AST Fri Apr 17 2026

A mid to upper-level trough will maintain an unstable weather
pattern across the regional waters, resulting in periods of strong
thunderstorms through at least Saturday. Thunderstorms will
produce locally higher winds, frequent lightning, and reduced
visibility. A surface high over the Atlantic will promote mainly
moderate easterly winds, occasionally fresh at times, resulting in
moderate to locally choppy seas over the weekend. A small
northeasterly swell will also continue to propagate across the
Atlantic waters and Caribbean passages through early next week.

&&

.BEACH FORECAST...
Issued at 214 PM AST Fri Apr 17 2026

A moderate risk of rip currents is present along the north-facing
beaches of Puerto Rico, Culebra, and the U.S. Virgin Islands this
afternoon and tonight. This means that life-threatening rip
currents are possible in the surf zone. This pattern is expected
to persist through the weekend and into early next week.
Beachgoers are encouraged to remain cautious in these exposed
areas. Meanwhile, along southern coastlines, a low risk is
present. However, keep in mind that life-threatening rip currents
often occur near groins, jetties, reefs, and piers, even when the
overall risk is low.

Another beach hazard is the development of thunderstorms each
afternoon, particularly along the western and northern beaches of
Puerto Rico. Remain weather-aware due to rapidly changing
conditions, and be prepared to seek shelter if you hear thunder.

A long-period northerly swell may arrive by midweek next week,
slightly deteriorating coastal conditions. Stay tuned to the
forecast.

&&

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

$$

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

NWS SJU Office Area Forecast Discussion