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125
FXCA62 TJSJ 060710
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
310 AM AST Mon Apr 6 2026

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

.KEY MESSAGES...
Updated at 300 AM AST Mon Apr 6 2026

* Flooding risk increases this week, highest through midweek.
  Afternoon and nighttime showers and thunderstorms may produce
  urban and small stream flooding, with isolated flash flooding
  possible across Puerto Rico and the US Virgin Islands.

* Life-threatening rip currents continue through this evening.
  High risk along north and east-facing beaches of Puerto Rico,
  Culebra, and St. Croix. Risk lowers on Tuesday, then increases
  again to high by Wednesday afternoon onward.

* Hazardous marine conditions continue for small craft. Small
  Craft Advisory remains in effect for Atlantic offshore waters
  and the Anegada Passage through at least this afternoon.
  Elsewhere, mariners should exercise caution.

* Breezy to locally windy conditions will persist. Winds will
  enhance shower activity and create hazardous marine and coastal
  conditions.

* Above-normal heat index values return Tuesday through Thursday.
  Elevated heat indices will increase the risk of heat- related
  impacts, especially for sensitive individuals outdoors without
  adequate hydration or cooling.

&&

.Short Term(Today through Wednesday)...
Issued at 300 AM AST Mon Apr 6 2026

Under an east-southeast wind flow, showers moved inland across
the windward areas of south and east PR, Vieques, Culebra, and the
US Virgin Islands, producing ponding in poorly drained areas.
However, heavy rain impacted the island of Vieques, where rainfall
accumulations ranged from 1 to 2 inches, according to Radar
estimates. Rain activity moved further inland across portions of
the eastern interior and northern PR during early morning.
Additionally, a cluster of strong thunderstorms was noted between
the coastal sites of northeast PR, Vieques, and Culebra, and over
the Atlantic Offshore waters. Winds across leeward locations were
calm to light and variable, while across the windward sites ranged
between 5 and 15 mph out from the east-southeast.

A strong surface high pressure extending from the western to
central Atlantic will promote breezy to windy east-southeast winds
across the northeast Caribbean through the short-term period, as
925 mb climatology suggests values will range near to above
normal. Additionally, a series of short-wave troughs at mid to
upper-level and a jet streak will promote a somewhat unstable
atmosphere today. These features, combined with above-normal Total
Precipitable Water, local and/or orographic effects, and sea
breeze variations, will likely result in showers and thunderstorms
as early as around noon and are more likely by the afternoon.
Another round of showers and possible thunderstorms will impact
the US Virgin Islands and the southeast or the eastern third of PR
from late this afternoon into the evening hours. Under this
weather pattern, we have forecast a limited to elevated risk of
flooding for portions of the islands during this period. Another
threat associated with this pattern is lightning and thunderstorm
winds.

The rest of the short term will remain unstable and wet as model
vs local climatology suggest, above normal moisture content, with
relatively steep lapse rates at mid and low levels, 250 mb heights
suggesting the presence of short wave troughs or an amplifying
trough, and cooler-than-normal temperatures at 500 mb, which are
favorable conditions for organized convection across the region.
Additionally, the winds will remain above normal through the short
term, and the 925 mb temperatures are expected to show a warmer-
than-normal trend, according to model guidance. Although we expect
periods with little or no rain, rounds of moderate to locally
heavy rain will impact portions of the islands each day,
especially across the USVI and PR`s windward locations overnight
and in the morning, and across the western and northern portions
of PR in the afternoon.

Under the aforementioned weather pattern, the weather threats for
Tuesday and Wednesday are warm to locally hot heat index during
the afternoon, a limited to elevated risk of flooding rain across
portions of PR and the USVI, breezy to locally windy conditions,
moderate to high risk of life-threatening rip currents, and
dangerous lightning near thunderstorm activity.

&&

.Long Term(Thursday through Monday)...
Issued at 300 AM AST Mon Apr 6 2026

A gradual transition toward a slightly more stable pattern is now
expected to begin earlier than indicated in previous model cycles,
particularly starting Thursday. Mid-level moisture is forecast to
decrease, with 700500 mb relative humidity values dropping closer
to near-normal levels. While the overall pattern will remain
somewhat moist, this trend suggests a modest reduction in the depth
of available moisture compared to earlier in the week.

Despite this drying trend, a generally unsettled pattern will
persist. Residual troughing aloft and lingering moisture will
continue to support periods of cloudiness and shower activity,
especially during the afternoon hours due to diurnal heating and
local effects. However, coverage and intensity of convection should
be somewhat lower than in previous days. Winds will remain from the
east-southeast, continuing to advect moisture into the region,
although not as efficiently as earlier in the week. Saturated soils
and elevated streamflows from rainfall earlier in the week will
continue to support an elevated flooding risk, although more
localized in nature, particularly across interior and western Puerto
Rico during the afternoon hours.

By Friday into Saturday, conditions are expected to become
relatively more stable, with mid-level drying limiting vertical
development of convection. This should result in more isolated to
scattered shower activity, primarily over western and interior
Puerto Rico during the afternoon, with more limited impacts
elsewhere.

By the end of the forecast period and beyond, model guidance
suggests a return to a wetter and more unstable pattern as another
deep-layered trough approaches the region and combines with well-
above-normal moisture. However, this portion of the forecast remains
in the longer range and carries higher uncertainty. Stay tuned for
further updates as confidence improves.

&&

.AVIATION...
(06Z TAFS)
Issued at 300 AM AST Mon Apr 6 2026

VFR conds are expected at local terminals, but MVFR/brief IFR may
occur due to passing rain SHRA/TSRA. Eastern terminals like TJSJ,
TIST, and TISX will experience SHRA/+SHRA, especially in the
morning and evening. Afternoon convection will mainly affect
interior, W/N PR, impacting JBQ/JSJ. Winds will be from the ESE at
5-12 kt thru 06/13Z, then at 10-20 kt, with higher gusts near
convection and due to sea breeze. Expect mountain obscuration,
reduced visibility in heavy rain, and isolated lightning.

&&

.MARINE...
Issued at 300 AM AST Mon Apr 6 2026

Hazardous marine conditions will persist through at least tonight as
a strong high-pressure system over the Atlantic maintains moderate
to fresh southeasterly winds. Therefore, expect confused seas
particularly across Atlantic waters and local passages throughout the
day. Conditions are expected to improve starting early Tuesday
morning, with seas subsiding to around 5 feet in the Atlantic and up
to 4 feet in the Caribbean. While trade wind showers continue to
drift across the region, isolated to scattered thunderstorms are
likely this afternoon, especially over coastal waters near western,
northern, and northwestern Puerto Rico. Expect shower and
thunderstorm coverage to increase slightly later this week as a
series of troughs interacts with deep tropical moisture.

&&

.BEACH FORECAST...
Issued at 300 AM AST Mon Apr 6 2026

A high risk of rip currents remains in effect through this afternoon
for the northern and eastern coasts of Puerto Rico, Culebra, and
St Croix. Life-threatening conditions are present, with breaking
waves around 6 feet along northern shorelines due to a fading
northeasterly swell and breezy conditions. While conditions will
gradually improve this evening through Tuesday, lowering the risk
to moderate, another arriving swell will cause conditions to
deteriorate again later this week. Beachgoers, especially
inexperienced swimmers, are strongly urged to stay out of the
water, avoid areas near rocks or jetties, and follow all posted
warnings and lifeguard instructions.

Additionally, passing showers and isolated afternoon thunderstorms
may produce gusty winds and brief heavy rainfall, particularly along
the northern and western coast of Puerto Rico. Remember: if you hear
thunder, seek shelter immediately. For location specific details,
please visit weather.gov/beach/sju.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk through this afternoon for PRZ001-002-005-
     008-012.

VI...High Rip Current Risk through this afternoon for VIZ002.

AM...Small Craft Advisory until midnight AST tonight for AMZ711.

     Small Craft Advisory until 6 AM AST early this morning for
     AMZ712-716-741.

     Small Craft Advisory until noon AST today for AMZ723.

&&

$$

KEY MESSAGES/SHORT TERM/AVIATION...CAM
LONG TERM...CVB
MARINE/BEACH FORECAST...GRS

NWS SJU Office Area Forecast Discussion