National Weather Service Today's Weather Impact Levels

900
FXCA62 TJSJ 230113 CCA
AFDSJU

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
913 PM AST Wed Apr 22 2026

.UPDATE...

A long period NNW swell will gradually build seas up to 7 feet and
occasionally higher from late tonight through Thursday across the
Atlantic waters. This swell will result in large braking waves
along the north facing beaches of PR, including Culebra, and the
northern USVI. Therefore, a High Rip Current Risk will be in
effect on Thursday for these areas. A Small Craft Advisory is now
in effect for the offshore Atlantic waters until Thursday
afternoon. Additional coastal zones could be added to the SCA as
offshore buoys indicated this afternoon seas 1-2 ft higher than
model data.

&&


.PREV DISCUSSION... /issued 202 PM AST Wed Apr 22 2026/

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

KEY MESSAGES...
Issued at 202 PM AST Wed Apr 22 2026

* Marine and beach conditions will gradually deteriorate tonight
  and tomorrow, Thursday, resulting in hazardous seas and life-
  threatening rip currents.

* An increasing risk of flooding across the north and west areas
  of Puerto Rico is expected by the end of the week and into the
  upcoming workweek.

* Heat indices around or exceeding 100 degrees are expected
  Sunday onwards.

* The primary hazards for the U.S. Virgin Islands will be a high
  risk of rip currents for the northern territories on Thursday,
  followed by a moderate risk over the next several days, along
  with a gradually increasing risk of heat toward the end of the
  forecast period across all islands.

Short Term(This evening through Friday)...
Issued at 202 PM AST Wed Apr 22 2026

Mostly sunny skies prevailed across Puerto Rico and the U.S.
Virgin Islands during the morning hours, becoming variably cloudy
by the afternoon. Maximum temperatures reached the mid-80s along
coastal areas and the mid to upper 70s across higher elevations.
Northeasterly winds of 5 to 10 mph were observed. Limited
afternoon convection is expected across southern and southwestern
Puerto Rico later today, with activity dissipating around sunset.

Low-level moisture is forecast to steadily increase throughout the
period, reaching values near 1.75 inches from Friday afternoon into
Saturday morning. This moisture surge is associated with the
remnants of an old frontal boundary north of the region and a trough
deepening across the tropical western Atlantic. However, most of the
moisture will remain confined below 750 mb. At lower levels, a
weakening high-pressure system over the central Atlantic will
gradually shift eastward, allowing an east-southeasterly wind flow
to become established across the local islands. This pattern will
advect deeper moisture into the region.

As a result, the available moisture combined with daytime heating
will support a more active convective regime, increasing the risk of
localized flooding, particularly toward the latter part of the
forecast cycle. On Thursday, convection is expected to concentrate
across central, southern, and southwestern Puerto Rico before
shifting to central, north and northwestern areas on Friday. With
the southeasterly wind flow, temperatures are expected to rise into
the 90s, with heat indices approaching 100F on Friday.

Long Term(Saturday through next Tuesday)...
Issued at 212 AM AST Wed Apr 22 2026

A surface high-pressure system positioned over the central Atlantic,
east of the Lesser Antilles, is expected to continue migrating
further eastward through early next week. As this system moves away,
winds will shift toward a more southerly flow, drawing tropical
moisture from the warm Caribbean waters into the region. At the same
time, lingering moisture from the remnants of a frontal boundary
will persist across the area through the upcoming weekend. This
atmospheric setup will drive daytime temperatures above normal,
particularly across coastal and urban areas of Puerto Rico and the
U.S. Virgin Islands. The combination of intense heat and abundant
moisture is expected to rise heat indices to 100F or higher.

While the weekend may see variable conditions, as pockets of drier
mid-level air arriving intermittently could limit widespread rain,
the combination of daytime heating and sea breeze convergence will
still likely trigger isolated to scattered afternoon thunderstorms.
This activity will be most concentrated over the interior and
northern regions, bringing the risk of frequent lightning, gusty
winds, and localized urban flooding.

By Monday afternoon into Tuesday, a deeper plume of moisture is
expected to arrive. The environment will become increasingly
unstable due to the arrival of this moisture alongside an upper-
level trough, likely leading to more widespread shower and
thunderstorm activity than over the weekend. While passing showers
remain a threat for all the islands, the most active rainfall is
expected over the interior and the western to northwestern portions
of Puerto Rico during the afternoon hours. Residents and visitors,
particularly those in flood-prone areas, are encouraged to monitor
weather conditions closely and remain aware of potential rapid river
rises and localized flooding through the midweek.

AVIATION...
(18Z TAFS)
Issued at 202 PM AST Wed Apr 22 2026

VFR conditions will continue to prevail at all TAF sites
throughout the forecast cycle, with brief MVFR conditions possible
at JPS through 22/22z in VCSH. The prevailing winds should remain
from E-NE at 5 to 10 kts, with gusts around 15 knots and some sea
breeze variations, becoming light and variable overnight.

MARINE...
Issued at 710 PM AST Wed Apr 22 2026

A surface high pressure extending from the Central into Eastern
Atlantic is interacting with a frontal boundary approaching from the
western Atlantic, promoting light to moderate northeasterly winds. A
long-period north-northwesterly swell is expected to arrive tonight
and spread across the local Atlantic waters, resulting in hazardous
conditions for small craft. Although the swell will diminish by late
Thursday night into Friday, another long-period swell from the
north-northeast should arrive on Saturday, however, seas are expected
to remain below small craft advisory criteria.

BEACH FORECAST...
Issued at 202 PM AST Wed Apr 22 2026

The moderate risk of rip currents continues across northern and
eastern Puerto Rico, a low risk elsewhere. Beachgoers are encouraged
to exercise caution, as life-threatening rip currents are possible
along the surf zone. Tonight, a long-period north-northwest swell
will arrive and spread across local Atlantic waters, with seas
increasing between 5 and 7 feet. The latest report from NDBC buoy
41043 showed seas around 4 feet, with a period of 11-12 seconds.
Taking into account swell decay and bathymetry, breaking waves
between 5 and 7 feet can be observed along the northern exposed
beaches of Puerto Rico and the U.S. Virgin Islands. Hence, a Rip
Current Statement has been issued for the northern beaches of
Puerto Rico, Culebra, and St. Thomas and St. John in the U.S.
Virgin Islands from 6 AM AST through 6 PM AST Thursday. Residents
and visitors are encouraged to check the beach forecast before
going out and follow the advice of flags, signs, and beach
patrols. Another long-period swell will likely arrive on Saturday,
bringing back hazardous conditions for beachgoers. For additional
information and location-specific rip current details, please
visit weather.gov/beach/sju.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk from 6 AM AST Thursday through Thursday
     afternoon for PRZ001-002-005-008-010-012.

VI...High Rip Current Risk from 6 AM AST Thursday through Thursday
     afternoon for VIZ001.

AM...Small Craft Advisory from midnight tonight to 6 PM AST Thursday
     for AMZ711.

&&

$$

UPDATE...DS

NWS SJU Office Area Forecast Discussion