451
FXCA62 TJSJ 290818
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
418 AM AST Sat Jun 29 2024

.SYNOPSIS...

A tropical wave is expected to move across the local area today
promoting afternoon convective activity over western Puerto Rico
and downwind of the smaller islands. Hot conditions are also
expected today across the region, and a Heat Advisory is in effect
for most of the coastal and urban areas of Puerto Rico and St.
Croix. Tropical activity is anticipated next week, with the
passage of Tropical Storm Beryl and a tropical wave south of the
area and over the Caribbean Waters.

&&

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

Trade wind showers and isolated thunderstorms increased throughout
the night across the regional waters and over portions of the
islands. The Doppler radar estimated around half an inch of rain
over eastern Puerto Rico. Minimum temperatures ranged from the upper
60s to mid-70s across the higher elevations and from the upper 70s
to low 80s across coastal municipalities. Winds were around 10 mph
from the east.

It will be hot again across the islands, and a Heat Advisory
(NPWSJU) was issued for St. Croix and the north, south, and western
coastal counties of Puerto Rico. Maximum temperatures should reach
the low 90s across the lower elevations, with heat indices ranging
between 108F and 112F.

Although mainly east winds prevail at the surface, an east-to-
southeast steering wind flow is expected today as a tropical wave
moves across the eastern Caribbean. Shower activity will continue to
increase in coverage, as will thunderstorms across the local waters.
Urban and small stream flooding is expected, particularly across
western PR during the afternoon. Trailing the wave, a Saharan Air
Layer with moderate amounts of Saharan dust should cause hazy skies
across the USVI by this afternoon. On Sunday and Monday, drier air
will continue to filter across the islands, with suspended Saharan
dust, causing hazy skies and limiting the potential for shower
activity throughout most of the period. Although isolated to
localized scattered showers cannot be ruled out, particularly during
the afternoon, excessive heat threat will continue as warm
temperatures prevail across the northeastern Caribbean and combine
with the Saharan Air Layer.

Weather conditions will quickly deteriorate during the night as the
outer bands from TC Beryl bring showers and thunderstorms across the
local area. Squally weather with strong gusty winds is possible
across portions of the Caribbean waters, the USVI, and east/southern
PR through early Tuesday.

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

Tropical activity will dominate much of the long term period with
the presence of Tropical Storm Beryl and a vigorous tropical wave in
the Eastern Tropical Atlantic.

The National Hurricane Center (NHC) is monitoring Tropical Storm
Beryl located in the Central Atlantic that it is forecast to
become a hurricane before reaching the Lesser Antilles. Latest
model guidance suggest that Beryl will stay well south of the
local islands as a category 2 hurricane. At this moment, the
closest point to Puerto Rico and the U.S. Virgin Islands will be
on Tuesday. Despite this system staying south of the islands over
the Caribbean waters, a broad field of moisture and external
bands could reach the local area. Therefore, an increase in
showers and thunderstorm activity associated to this system is
anticipated. With the expected conditions, some potential hazards
are: flooding, mudslides, and river rises.

A drier airmass will quickly follow Beryl as it moves away from the
region towards The Hispaniola. This drier airmass will bring some
Saharan Dust particles promoting slightly hazy skies. However,
this dry weather pattern will not last long due to the fast
approach of a tropical wave behind Beryl with the potential of
becoming a tropical cyclone. Model guidance suggest the
development of this wave, and moving this system close to the
local area by Thursday. Similarly to Beryl, this wave is nor
expected to have direct impacts over Puerto Rico and the U.S.
Virgin Islands. However, it is expected to bring shower activity
over the region.

Residents and visitors of Puerto Rico and the U.S. Virgin Islands
should continue to monitor the progress of both systems as they
move towards the Caribbean over the next few days.

&&

.AVIATION...

(06Z TAFS)

SHRA/TSRA expected to increase across the local area due to a
tropical wave passage across the Caribbean Sea. Tempo MVFR
conditions are possible in and around TJPS/TJSJ/TJBQ btw 29/15z-21z.
Across the USVI terminals, mostly VFR conditions are expected with
VCSH prevailing thru the mid afternoon hours. HZ due to Saharan dust
will gradually increase across the USVI terminals into eastern PR
before sunset. East winds at 12-16 kt with stronger gusts and sea
breeze variations aft 29/14z.

&&

.MARINE...

A surface high pressure over the central Atlantic will promote light
to moderate easterly winds. Trade wind showers will move across the
regional waters from time to time due to a tropical wave moving south
over the Caribbean Waters today. Tropical Storm Beryl is forecast to
strengthen as it approaches the Caribbean waters late Monday night
into Tuesday, deteriorating marine and coastal conditions
considerably for the Caribbean and local passages.


&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Heat Advisory from 10 AM this morning to 5 PM AST this afternoon
     for PRZ001-003-005-007-008-010-011.

VI...Heat Advisory from 10 AM this morning to 5 PM AST this afternoon
     for VIZ002.

AM...None.
&&

$$

SHORT TERM...DS
LONG TERM....GRS