503
FXCA62 TJSJ 190549
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
149 AM AST Sun Apr 19 2026

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

.KEY MESSAGES...
Updated at 131 AM AST Sun Apr 19 2026

* Flooding risk will be highest this afternoon due to showers and
  thunderstorms. Elevated risk will persists through today and
  decreasing to limited from Monday onward.

* Thunderstorms will bring frequent lightning and gusty winds.
  Saturated soils increase the risk of downed trees and power lines.
  Small hail and brief funnel clouds or waterspouts are possible.

* Improving weather conditions across the US Virgin Islands and
  Puerto Rico from late today.

* Choppy, wind-driven seas will continue, with locally dangerous
  conditions near thunderstorms. A moderate risk of rip currents
  will persist along north facing beaches of Puerto Rico and the
  U.S. Virgin Islands.

&&

.Short Term(Today through Tuesday)...
Issued at 131 AM AST Sun Apr 19 2026

Overnight, most showers shifted over the surrounding waters, with
some activity filtering across the eastern half of Puerto Rico,
Vieques, Culebra, and the U.S. Virgin Islands. Rainfall
accumulations were generally light, and conditions remained
relatively calm. Winds were light and variable, with temperatures
in the 70s across urban and coastal areas and in the 60s across
the mountainous interior. A Flood Warning remains in effect for
the Culebrinas River due to previous rainfall, which has kept
river levels elevated and continues to impact nearby areas and
roadways.

For today, residual moisture will support passing showers at times
across eastern Puerto Rico during the morning hours, followed by
an increase in rainfall and thunderstorm development this
afternoon across the interior and western portions of the island.
The latest model guidance indicates above-normal precipitable
water values, mid-level moisture, and relatively cool 500 mb
temperatures favoring convective development. As a result, the
flooding risk will remain limited to elevated, particularly in
areas experiencing persistent or repeated rainfall. Despite this
activity, a gradual introduction of drier air is expected to begin
through the day.

From Monday into Tuesday, drier and more stable conditions are
expected as an upper-level trough shifts eastward and a mid-level
ridge builds from the west. A drier airmass filtering in from the
northeast will limit moisture depth, with most moisture confined
below around 700800 mb. Even so, typical diurnal convection will
persist, with afternoon showers and isolated thunderstorms
developing over interior and western Puerto Rico, along with
passing showers affecting eastern areas overnight and during the
morning hours. Flooding risk will decrease to limited, although
localized impacts will remain possible where heavier showers
develop.

Overall, the primary hazards will continue to include urban and
small stream flooding, rapid river rises, landslides, and
lightning. Soils remain saturated and rivers elevated, resulting
in a low threshold for flooding impacts. Persistent or repeated
showers and thunderstorms may quickly lead to localized flooding,
particularly in flood-prone and mountainous areas. Gusty winds
associated with thunderstorms could result in isolated downed
trees and power lines. While conditions gradually improve by
Monday, localized hazards will persist through Tuesday where
heavier rainfall occurs. Residents and visitors should remain
alert and continue to monitor the latest forecasts.

&&

.Long Term(Wednesday through Sunday)...
Issued at 131 AM AST Sun Apr 19 2026

A shift towards relatively drier and more stable conditions is
forecast to start the long term period with seasonal Precipitable
Water (PWAT) values. PWAT values are forecast to generally stay at
normal, though periods of high-end normal to above-normal values are
possible as moisture is steered towards from the Caribbean to the
region. A series of surface highs and frontal lows will dominate the
local wind pattern, maintain light to moderate northeasterly, then
southeasterly, then southerly and then southwesterly winds during
the period. Local weather will be seasonal. Expect passing showers
over windward sectors during the morning and afternoon hours. The
focus of afternoon convective activity will vary in location each
day. On Wednesday and Thursday, interior to southwestern Puerto
Rico. On Friday and Saturday, interior to northern Puerto Rico. On
Sunday, north-central to northeastern Puerto Rico. The combination
of available moisture, daytime heating, and local effects could lead
to moderate to heavy rainfall and isolated thunderstorms during
these afternoon periods. Temperatures at the 500 mb level are
forecast to remain seasonal. Isolated thunderstorms are forecast
each afternoon, particularly toward the end of the period due to a
nearby mid-to-upper trough. Temperatures at 925 mb will also stay
seasonal throughout most of the period, although increasing to above
normal at times under the southerly flow.

&&

.AVIATION...
(06Z TAFS)
Issued at 131 AM AST Sun Apr 19 2026

VFR conditions across all TAF sites. Periods of brief MVFR with
VCTS/SHRA after 19/17Z across TJSJ and TJBQ. Prevailing winds
should remain from east around 10 to 15 kts gusts around 25 knots
after 19/14Z or near VCTS/SHRA and with sea breeze variations.

&&

.MARINE...
Issued at 131 AM AST Sun Apr 19 2026

Periods of strong thunderstorms, particularly across the western
waters of Puerto Rico are expected during the afternoon hours. A
surface high pressure over the Atlantic will promote mainly
moderate to fresh easterly winds across the offshore Atlantic
waters and local Caribbean passages, resulting in moderate to
locally choppy seas through today. Small craft operators should
exercise caution. A small northeasterly swell will also continue
to propagate across the Atlantic waters and Caribbean passages
through early this week.

&&

.BEACH FORECAST...
Issued at 131 AM AST Sun Apr 19 2026

A moderate risk of rip currents is expected to persist throughout
the week across northern exposed beaches. This may result in
life- threatening rip currents. Heed the advice of lifeguards,
beach patrol flags, and posted signs.

A moderate risk of rip currents is expected to continue throughout
the week along northern exposed beaches. Although the risk is
moderate, rip currents can still become life-threatening. Always
follow the guidance of lifeguards, beach patrol flags, and posted
warning signs.

Visitors should also stay alert to changing weather conditions in
addition to surf hazards. An unsettled weather pattern will persist
at least through today, with the potential for heavy showers and
thunderstorms capable of producing locally gusty winds and brief
heavy rainfall, especially during the afternoon hours. Remain
weather-aware, as conditions can change quickly, and be prepared to
seek shelter immediately if thunder is heard.

For additional information and location-specific rip current
details, please visit: weather.gov/beach/sju.

&&

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

$$

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

NWS SJU Office Area Forecast Discussion