732
FXCA62 TJSJ 080850
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
450 AM AST Sat Jun 8 2024

.SYNOPSIS...

Stable weather conditions along with warm to hot temperatures are
expected to prevail throughout weekend. As a result, An Excessive
Heat Warning (NPWSJU) is in effect today for lower elevations and
coastal areas of mainland Puerto Rico and a Heat Advisory for
Culebra, Vieques, St Croix, St John, and St Thomas. An Excessive
Heat Watch is in effect for Sunday across the same areas. For the
upcoming workweek, another tropical wave will enhance shower
activity across the local waters and some regions of Puerto Rico.

&&

.SHORT TERM...Today through Monday...

An overnight radar and satellite imagery analysis indicated that
clear to partly cloudy skies dominated the region. However, a
westward-moving line of showers generated variable cloudy skies and
rainfall accumulations of up to a tenth of an inch in portions of
the US Virgin Islands, Vieques, and Culebra. Reports from official
sites indicate that overnight minimum temperatures stayed above 80
degrees across the local islands and coastal areas of northeastern,
south-central, and southwestern Puerto Rico. In higher elevations,
temperatures dropped to the upper 60s. Winds were mainly light to
calm and variable, increasing to about 8-12 mph near the showers.

Weather conditions throughout the short-term forecast should remain
relatively stable due to a drier-than-normal airmass and consistent
mid-level ridging across the region. East-to-east-southeast trade
winds will return today and persist throughout the forecast period,
with peak daytime wind speeds ranging from 10 to 15 mph, driven by a
high-pressure system over the central Atlantic. Precipitable water
levels will drop below seasonal levels to around 1.3-1.4 inches
today before returning to more typical values of 1.7-1.9 inches on
Sunday and Monday, influenced by a distant tropical wave passing
well south of the local islands. Despite these moisture
fluctuations, shower activity will remain limited throughout the
forecast period, primarily induced by daytime heating over the far
western-to-northwestern sections of Puerto Rico. Passing shower
frequency may increase from Sunday evening into Monday morning due
to the proximity of the tropical wave, impacting eastern Puerto
Rico, Vieques, Culebra, and the US Virgin Islands. However, no
flooding impacts are anticipated.

In terms of temperatures, dangerously hot conditions will return
today. As a result, Excessive Heat Warnings are in effect from 9 AM
to 6 PM AST for all lower elevations and coastal areas of Puerto
Rico, posing a threat to anyone without effective cooling and/or
adequate hydration. Meanwhile, Heat Advisories have been issued for
Vieques, Culebra, and the US Virgin Islands, posing a risk to most
individuals sensitive to heat. Remember to take extra precautions
when outside. Wear lightweight and loose-fitting clothing. Try to
limit strenuous activities to early morning or evening. It is
essential to stay hydrated and watch for signs of heat exhaustion.
Due to the likelihood of these extreme heat conditions continuing,
an Excessive Heat Watch is now in place for Sunday.

&&

.LONG TERM...Tuesday through Saturday...

A surface high pressure extending from the eastern to central
Atlantic will continue to promote southeasterly winds throughout
the upcoming week. We foresee a change in the weather pattern to
begin Tuesday afternoon into Wednesday as patches of moisture
associated with an approaching tropical wave. The latest
Precipitable Water (PW) models suggest values increasing to normal
climatological levels, around 1.6 to 1.9 inches from Tuesday
night into Wednesday. That moisture field could increase the
frequency or intensity of the showers across the regional waters
resulting in better rain chances, especially across the Caribbean
waters and portions of the islands. By Thursday, the low-level
southeasterly winds will push a drier airmass, which probably will
briefly limit rain development that day. However, at the end of
the week, models agree that additional moisture from another
surface disturbance will also reach the island along with an
upper-level trough and further enhance the chance of showers
through the weekend.

Temperature-wise, even tho temperatures should improve, limited to
elevated excessive heat risk is anticipated to continue across
lower elevations and coastal areas of Puerto Rico and the rest of
the islands.

&&

.AVIATION...
(06Z TAFs)

VFR conditions will likely prevail across all terminals during
the next 24 hours. Light to calm and variable winds will turn from
the E-ESE at 10-15 knots between 08/13-22Z, accompanied by higher
gusts and sea breeze variations.

&&

.MARINE...

Mainly stable weather conditions are forecast for the rest of the
weekend due to a drier air mass and a mid to upper level ridge. A
surface high pressure extending from the eastern Atlantic into
the central Atlantic will continue to promote light to moderate
southeasterly winds through the forecast period. For the upcoming
week, a tropical wave is expected to approach from the southeast
with better potential for showers and isolated thunderstorms
across the waters and local passages.

&&

.BEACH FORECAST...

Tranquil marine conditions are forecast to prevail for the next
several days. As a result, a low risk of rip currents is expected
across most beaches of Puerto Rico and the U.S. Virgin Islands
through early next week, except for St Croix that have a moderate
risk. Around midweek through the end of the week, a mix of low to
moderate risk is anticipated. For more information and details
about the latest forecast please refer to the Surf Zone Forecast
(SRFSJU).

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Excessive Heat Warning from 9 AM this morning to 6 PM AST this
     evening for PRZ001>003-005-007-008-010-011.

     Excessive Heat Watch from Sunday morning through Sunday
     afternoon for PRZ001>003-005-007-008-010>013.

     Heat Advisory from 9 AM this morning to 6 PM AST this evening
     for PRZ012-013.

VI...Excessive Heat Watch from Sunday morning through Sunday
     afternoon for VIZ001-002.

     Heat Advisory from 9 AM this morning to 6 PM AST this evening
     for VIZ001-002.

AM...None.

&&

$$

SHORT TERM/AVIATION...ICP
LONG TERM/MARINE/BEACH....YZR