770
FXCA62 TJSJ 302138
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
538 PM AST Tue Apr 30 2024

.SYNOPSIS...

A broad surface high pressure over the western Atlantic will
weaken in the next few days. Expect breezy northeasterly winds
through at least midweek. From mid-week onwards, instability and
moisture levels increase once again as a mid to upper level trough
lingers over the western Atlantic and lighter east to southeast
winds return. Marine conditions will remain hazardous through at
least tomorrow night. A High Risk of Rip Currents will continue
across northern and eastern coastline of Puerto Rico and Culebra
through at least Thursday afternoon.

&&

.SHORT TERM...Tonight through Thursday...

During the morning, a similar pattern continued with showers
moving across northern, eastern, and interior portions of PR and
the US Virgin Islands. Doppler radar estimates registered around
one inch or less in those areas. By the afternoon, rain focused
over west central municipalities. At the moment, around 2 to 4
inches of rain has fallen. A Flood Advisory continues in effect
until 6 PM AST this evening. In addition, activity of thunderstorms
has persisted over the Caribbean waters, with winds at around 30
knots. Tonight, like the past few nights, expect additional
showers developing across portions of the USVI, northern, and
eastern sectors of Puerto Rico, and the Caribbean waters, along
with some breezy and gusty periods.Minimum temperatures will
range from the mid and upper 70s across coastal areas to the
mid-60s in the higher elevations.

The latest model`s guidance continues in agreement that the surface
high pressure; now located over the western Atlantic, will weaken
during the next few days as it moves into the Central Atlantic
changing the wind flow across the forecast area. Winds should
gradually turn from the east tomorrow and become lighter tomorrow
evening through the rest of the short term.

Not a lot of improvement is expected for the next several days, on
the contrary, a wetter and more unstable pattern should evolve on
Wednesday and Thursday as an upper-level trough approaches the
area from the west, and an induced surface trough develops north
of the region. Consequently, above-normal moisture levels for this
time of the year will prevail over the local region enhancing
shower and thunderstorm development across much of Puerto Rico and
USVI. For that reason, the risk of flooding will likely remain
elevated across most islands every day for the rest of the period
and the main impacts remain to be: urban and small stream
flooding, localized flash flooding, and mudslides in areas of
steep terrain. It is crucial to be cautious and aware of these
potential risks, as well as monitor the forecast for future
updates.

&&

.LONG TERM...Friday through Monday...
.PREV DISCUSSION... /issued 423 AM AST Tue Apr 30 2024/

The latest model guidance continues to suggest wet and unstable weather
conditions even through the end of the workweek, notonly for the
island of Puerto Rico but also for the U.S. Virgin Islands. This
pattern should prevail as an upper-level trough approaches the
area from the west, and an induced surface trough develops north
of the region enhancing additional rainfall activity and allowing
it to be the dominant feature throughout the long-term period. On
Friday, a mid to upper level, yet maxima, should move across the
area with winds around 70 knots. This yet maxima will allow the
trough to deepen, enhancing the unstable conditions. By the
weekend, expect the Precipitable Water (PW) values to range above
normal climatological levels for this of the year to above two
standard deviations. We foresee active afternoons each day with
the potential increase in the frequency of showers and isolated
thunderstorms. As a side note, heat indices across the lower
elevations of the islands could likely range between 102 and 106
degrees on Friday and Saturday before the onset of afternoon
convection.

Overall, the main hazards from Friday into the beginning of the workweek
are the increased risk of flooding across the islands and the
risk of mudslides, particularly in areas of steep terrain in
Puerto Rico. Therefore, we encourage citizens and visitors to be
aware of any additional updates in the forecast.

&&

.AVIATION...
(18z) TAFS

Expect showery weather with breezy trade winds through the forecast
period. TSRA/SHRA will affect mainland PR and downwind from St
Croix, some SHRA/+SHRA may impact JBQ/JPS/ISX this afternoon.
Mountain obsc will prevail along the Cordillera Central and near the
Luquillo Mountain Range thru 30/23z. The unstable and wet pattern
will continue tomorrow. We expect 10-20 kt easterly winds with gusts
btwn 20 and 30 kt, aft 30/23z winds will range between 5-15 kt and
will return from the E-ESE aft 01/13z at 15-20 kt.

&&

.MARINE...

A surface high pressure across the western to central Atlantic
will tighten the local pressure gradient, promoting moderate to
locally fresh trade winds across the Northeast Caribbean through
at least tomorrow. As a result, expect hazardous seas for small
craft operators due to confused seas associated with the
increasing winds and a northeasterly swell spreading across the
local waters. An induced surface trough, north of the islands,
will weaken the pressure gradient and winds will shift from the
east to east-southeast by the latter part of the week.

&&

.BEACH FORECAST...

A northerly swell and stronger winds are resulting in High Risk
of Rip Currents across local area beaches. The High Risk will
continue in St. Croix until this afternoon, across western beaches
of Puerto Rico, St. Thomas, and St. John through at least late
Wednesday, and across the northern and eastern coastline of
Puerto Rico and Culebra through at least Thursday afternoon. For
more information and details about the latest forecast please
refer to the Surf Zone Forecast (SRFSJU) and the Coastal Hazard
Message product (CFWSJU).

&&

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

     High Rip Current Risk through late Wednesday night for PRZ010.

VI...High Rip Current Risk through late Wednesday night for VIZ001.

     High Rip Current Risk until 6 PM AST this evening for VIZ002.

AM...Small Craft Advisory until midnight AST Wednesday night for
     AMZ711-712-716.

     Small Craft Advisory until noon AST Wednesday for AMZ723-741-742.

     Small Craft Advisory until 6 PM AST this evening for AMZ726.

&&

$$

SHORT TERM/MARINE/BEACH FORECAST...YZR
LONG TERM....MMC
AVIATION...CAM/CVB
PUBLIC...ERG