076
FXCA62 TJSJ 262104
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
504 PM AST Wed Jun 26 2024

.SYNOPSIS...

A stable weather pattern will persist for the short term, with
warm conditions during the daytime and afternoon convection for
some areas of the region. The islands will be on a wet trend for
the upcoming workweek, with tropical moisture moving near the
region, increasing the potential for shower activity. There is
some interest in the tropical forecast for the upcoming seven
days, as the National Hurricane Center is monitoring a vigorous
tropical wave with a moderate chance of formation chance.
Residents in Puerto Rico and the U.S. Virgin Islands should always
stay tuned with the latest information using official sources.

&&

.SHORT TERM...Tonight through Friday...

The islands experienced another warm day, with an Excessive Heat
Warning and an Advisory still in effect for most of the urban and
coastal areas of Puerto Rico. According to non-official weather
stations across the island, heat indices fluctuated between 108
and 113 degrees Fahrenheit. Around 1 PM, afternoon convection
started to develop across the northwestern quadrant. Showers were
intense, with gusty winds and frequent lightning, with rainfall
accumulations around 2 inches between Moca & Aguada. Another
segment of showers affected the north-central region, with almost
the same rainfall accumulations in a localized area over
southwestern Arecibo municipality.

For the rest of the afternoon and evening hours, the islands will
continue to experience warmer conditions across most coastal
areas and some urban regions in the big cities. The Saharan Dust
Layer, a key contributor to the current weather, will continue
moving westward out of the region. However, particulates will be
present tomorrow, maintaining the warmer conditions. Under this
pattern of Saharan Dust across the region, with some moisture
embedded in the easterly winds, the islands will observe a similar
pattern for tomorrow, with warmer morning conditions followed by
some localized afternoon convection across the western interior.
By Friday, the islands will remain under the divergence side of an
upper-level trough. Therefore, the islands will continue to hold
under a stable weather pattern with minimal rainfall activity,
with only localized showers for the local and diurnal heating over
the western interior sections.

.LONG TERM...Saturday through Wednesday...

...from previous discussion issued at 404 AM AST Wed Jun 26
2024...

The latest precipitable water guidance suggests values ranging
around normal climatological levels across Puerto Rico and the U.S.
Virgin Islands during the weekend. Nonetheless, as a surface
high-pressure system positions across the Atlantic basin, we
anticipate the introduction of tropical moisture into the islands
through at least the upcoming workweek. This weather pattern will
allow moisture to filter over the islands from time to time, and
this, combined with the diurnal heating, will promote the
development of afternoon showers and isolated thunderstorms,
particularly across the western interior sections of Puerto Rico,
as mostly easterly winds will dominate the forecast area. As
mentioned in previous discussions, the tourists and citizens of
Puerto Rico and the U.S. Virgin Islands will experience a slight
change in weather conditions as drier air will filter across the
region on Monday, reducing the chance of showers through Tuesday.
Nevertheless, a typical seasonal weather pattern of passing
showers and afternoon convection is expected.

On Wednesday, expect a gradual increase in shower and possible
thunderstorm activity across the forecast area, particularly over
the Caribbean waters, as a tropical wave now being monitored by
the National Hurricane Center moves south of us. However, we
encourage people to stay updated with any changes in the forecast.

&&


&&

.AVIATION...
Mainly VFR conditions are expected to prevail across all terminals
during the forecast period. Hazy skies due to the presence of
Saharan dust could result in lower VIS, around 6-9 miles. SHRA/TSRA
is expected to develop btw 26/18z-22z in and around TJBQ with
intermittent MVFR conds possible. A few VCSH or -RA are possible
during the overnight period across eastern TAF sites, but confidence
is not high enough to include in the TAFs at this moment. Winds will
remain mainly from the E/ESE at 10-20 kt with gusts between 20 and
30 kt for the rest of the afternoon hours, then become lighter
during the evening and overnight hours.

&&

.MARINE...

A surface high pressure over the central Atlantic, extending all
the way to the Caribbean, will hold a moderate easterly wind
pattern across the region. Therefore, seas will remain between 3
and 4 feet, even less for the coastal waters. By the beginning of
the upcoming workweek, building seas are forecast as a vigorous
tropical wave, now monitored by the National Hurricane Center,
moving over the Caribbean Waters, increasing the seas to 8 feet.
Mariners should keep track of the tropical forecast for further
updates on the expected conditions. Also, regarding the moisture
field that accompanied the tropical wave, the forecast calls for
thunderstorm activity, which could lead to even more localized
hazardous conditions. For the coastal areas, the risk of rip
currents will continue to moderate for some areas and low for the
rest of the areas.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Excessive Heat Warning until 6 PM AST this evening for PRZ001-
     003-005-007-008-010>012.

     Heat Advisory until 6 PM AST this evening for PRZ002-013.

VI...Excessive Heat Warning until 6 PM AST this evening for VIZ002.

     Heat Advisory until 6 PM AST this evening for VIZ001.

AM...None.
&&

$$

SHORT TERM...LIS
LONG TERM....MRR
AVIATION...YZR/ERG
PUBLIC...RVT