206
FXCA62 TJSJ 282016
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
416 PM AST Tue May 28 2024

.SYNOPSIS...

Expect, marginally unstable weather conditions to persist across
the region through the next several days. An east-southeasterly
wind flow will continue to bring plenty of tropical moisture from
the warmer Caribbean waters, enhancing the potential for strong
showers and thunderstorms over the interior and northwestern
Puerto Rico each afternoon.A relatively drier airmass is expected
to filter into the region by the end of the workweek, promoting
stable weather conditions and warm to hot temperatures.

&&

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

Today, the weather conditions played an important role across
Puerto Rico and the U.S. Virgin Islands. A combination of hazy
skies, warm weather, and periods of rainfall prevailed. Light
showers filtered across the eastern half of Puerto Rico and the
island of Saint Thomas during the morning hours, and by the late
morning, showers developed along the San Juan metro areas and over
the interior municipalities, leaving around an inch of rain. The
typical afternoon convection developed over the northwestern
sections of Puerto Rico, where the concentrations ranged above an
inch of rain. Temperature-wise, they remained in the upper 80s to
low 90s along the coastal and urban areas, while over the higher
elevations, they stayed in the 80s. These high temperatures,
combined with the available moisture, allowed the heat indices to
be above 112 degrees Fahrenheit along the northern coast of Puerto
Rico, where the Excessive Heat Warning was in effect. The
remaining coastal areas of Puerto Rico, Culebra, Vieques, and the
U.S. Virgin Islands stayed with the Heat Advisory. Overall, all
the islands experienced hot conditions. Like in previous days, the
prevailing wind flow was out of the east-southeast.

Overnight, expect variably cloudy skies across the region. The
eastern sections of Puerto Rico and the island of Saint Thomas
should experience some showers as patches of moisture move across
the area from time to time. The temperatures will range in the
upper 60s to low 70s across higher elevations to the lower 80s
along the coastal areas. Wind-wise, they should stay generally
light and variable, influenced by land breezes.

Weather conditions will gradually transition to a more typical
seasonal shower pattern, driven by diurnal heating and local effects,
with enhanced afternoon convective development over the interior
and west to northwestern Puerto Rico each day. Afternoon
convection is also possible elsewhere. We foresee limited to
elevated flooding risks in urban areas, roads, small streams, and
washes, particularly over the northwestern PR during the
afternoon.

As mentioned in previous discussions, despite persistent cloud cover
and high rain probabilities, warmer-than-normal conditions will
continue. Coastal and urban areas are expected to have lows in the
lower 80s, while higher elevations may see lows around 70
degrees. In contrast, highs will range from the lower 90s in lower
elevations to the upper 70s in higher elevations. With ample
moisture present, heat indices may exceed 108 degrees Fahrenheit
in many coastal and urban areas, with some locations experiencing
brief periods of 112 degrees or higher.These warm conditions pose
a significant health risk, prompting the issuance of Excessive
Heat Warnings/Advisories. Regarding the hazy skies, expect them to
continue as some particles of Saharan Dust and dry air filter
across the islands from time to time. Residents and visitors
should take necessary precautions, particularly those engaging in
outdoor activities.

&&

.LONG TERM...Friday through Tuesday...
//from previous discussion//

A mid-to-upper level ridge moving from the south-southeast into the
local area will promote relatively drier weather conditions and
warmer temperatures. Nonetheless, light wind flow from the southeast
in combination with daytime heating and local effects will enhance
showers and thunderstorm development across the northwestern
portions of Puerto Rico each afternoon. Despite of the presence of
the ridge, tropical moisture being pulled from the warm Caribbean
Waters will approach the local area by late Saturday. The latest
Precipitable Water Content Analysis suggest values from 1.9 to 2.45
through the period. Due to the expected conditions, there is a
limited to elevated risk of urban and small stream flooding and
isolated flash flooding mainly for central, northern and
northwestern Puerto Rico. By Sunday into Tuesday a weak surface
trough is forecast to develop west of our area, increasing once
again the potential for moderate to heavy rainfall across the
islands. Warmer temperatures are expected to persist through the
entire period with values between the upper 80s to low 90s along the
coastal and urban areas of the islands. Heat indices are likely to
surpass the mid 100s, resulting in excessive heat conditions for the
islands.

&&

.AVIATION...
(18z TAFs)

SHRA/VCTS will result in gusty winds btwn 15-25kt, and will affect
TJBQ thru 28/23z. Winds will prevail mainly from the E-ESE at 15 kt
or less, pushing passing SHRA across the windward sites overnight.
Afternoon convection will develop tomorrow (29/16-22z) across PR`s
mountain areas and downwind from the USVI. Expect E winds at 10-15
kt with sea breeze variations and higher gusts near TSRA after
29/13z, tomorrow.

&&

.MARINE...

A moderate east to southeast wind flow will prevail across the region
over the next few days. Showers and isolated thunderstorms associated
with the trailing moisture of a departing tropical wave and a surface
trough east of us will continue to affect the regional waters and local
passages. So far, the next tropical wave, located in the central
tropical Atlantic near 50W, is forecast to approach the regional
waters by mid-week, with its bulk of moisture well to the south
across the Caribbean Sea.

&&

.BEACH FORECAST...

There is a low risk of rip currents across all beaches of Puerto
Rico and the U.S. Virgin Islands tonight. Moderate to heavy
showers and isolated thunderstorms are possible each afternoon
mainly across the northwestern waters of Puerto Rico.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Excessive Heat Warning until 6 PM AST Wednesday for PRZ001-005-
     008.

     Heat Advisory until 6 PM AST Wednesday for PRZ002-003-007-
     010>013.

VI...Heat Advisory until 6 PM AST Wednesday for VIZ001-002.

AM...None.
&&

$$

SHORT TERM...MMC/RAM
LONG TERM....GRS
AVIATION...CAM
PUBLIC DESK...LIS