415
FXCA62 TJSJ 190814
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
414 AM AST Sun May 19 2024

.SYNOPSIS...
For the rest of the weekend, the heat and the haze continue under
a generally southeast surface flow. A wet, unstable weather pattern
is expected through the second half of the week as a deep layered
trough moves through the Caribbean basin. Tranquil marine conditions
will prevail throughout the next few days. The risk of rip
currents is low.

&&

.SHORT TERM...Today through Tuesday...

A few showers managed to reach eastern Puerto Rico early in the
morning, while an isolated thunderstorm was observed across the
waters far away from land. The day will be similar to yesterday.
First of al, a high pressure over the eastern Atlantic maintains
light trade winds from the southeast at the surface, with a more
southerly component from 900 to 600 mb. This will maintain
temperatures above normal, so hot conditions will prevail for the
next several days. In fact, heat indices are expected to surpass 102
degrees across most of the coastal and urban areas in Puerto Rico
and in the Virgin Islands. The aerosol models show low
concentrations of Saharan dust too, hence hazy skies are
anticipated.

Additionally, a pocket of enhanced moisture should reach the islands
today too, increasing the frequency of showers a little. However,
the heaviest activity is anticipated for the interior, north-central
and northwest, where showers and isolated thunderstorms are expected
to fire up later this afternoon. The risk for urban and small stream
flooding is elevated.

For the rest of the week, the heat and the haze continue under a
generally southeast surface flow. The wind flow does gain a
southwesterly component at the mid levels in response of a deep-
layered trough that will develop in the western Caribbean. The
afternoon activity should develop again in the interior and
northwest, but as the showers gain more altitude, they may move
closer to the San Juan metro area.

&&

.LONG TERM...Wednesday through Sunday...

A wet, unstable weather pattern is expected through the second half
of the week as a deep layered trough moves through the Caribbean
basin to then form a surface low in the western Atlantic by the
weekend. The surface induced trough that is projected to form
south of Hispanola on Wednesday night will cause an acceleration
of the surface winds along with a rapid increase of moisture
sourced from the ITCZ as the airmass moves northward in the
eastern Caribbean. Winds will continue to veer towards a southerly
direction by the end of the week as the low strengthens to the
northwest of the area. Throughout this time the proximity of the
low`s mid to upper-level jet will maintain strong winds aloft
which will increase the chance of thunderstorm activity as
ventilation is enhanced. Conditions seem to calm through the
weekend as this system moves further from the local area, however
light surface wind flow and abundant moisture will allow diurnal
heating and local effects to bring heavy rainfall during the
afternoon hours.

Due to all of this, Wednesday through the weekend will consist of
periods of heavy rainfall for mostly all of Puerto Rico and the
USVI. Flash flooding due to continuous rainfall is possible through
this event also strong thunderstorms are also likely to occur. Stay
tuned for further updates as we approach these days.

&&

.AVIATION...

(06Z TAFS) Mainly VFR conditions expected to prevail. SHRA and
isolated TSRA will move across the Caribbean waters, and could reach
the USVI and TJSJ terminals at times. After 17Z, additional
development expected, for the Cordillera Central and around TJBQ,
where periods of reduced VIS and low ceilings are possible. Winds
will from the SE at 8-13 kts, with stronger wind gusts and sea
breezes variations.


&&

.MARINE...
A surface high pressure across the central and northeast Atlantic
will result in moderate easterly winds through the rest of the weekend.
Tranquil marine conditions will therefore prevail throughout the
forecast period. Afternoon showers and isolated thunderstorms could
move from western Puerto Rico into the coastal waters each day.


&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Heat Advisory from 11 AM this morning to 5 PM AST this afternoon
     for PRZ001-002-005-008-010-011.

VI...Heat Advisory from 11 AM this morning to 5 PM AST this afternoon
     for VIZ002.

AM...None.

&&

$$

SHORT TERM...ERG
LONG TERM....RC