648
FXCA62 TJSJ 101420
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
1020 AM AST Mon Jun 10 2024

.UPDATE...

Fair weather conditions will continue to prevail today with hot
temperatures and limited rainfall activity. Showers if any will be
focused across western areas of Puerto Rico. Pops were adjusted
to match current Wx conditions.

&&

.AVIATION...

VFR conditions are expected at all TAF sites during the next 24
hours. At least through 10/22Z, afternoon VCSH/SHRA may briefly
impact operations across TJBQ. Light to calm, variable winds will
turn from the E-ESE at 12-16 knots between 10/13-22Z, accompanied
by higher gusts and sea breeze variations.

&&

.PREV DISCUSSION... /issued 436 AM AST Mon Jun 10 2024/

SYNOPSIS...

Hot conditions return today. Excessive Heat Warnings are in
effect from 9 AM to 6 PM AST for all lower elevations and coastal
areas of Puerto Rico. Heat Advisories are in effect from 9 AM to 6
PM AST for Vieques, Culebra, and the US Virgin Islands.Due to the
likelihood of these extreme heat conditions continuing, an
Excessive Heat Watch is now in place for Tuesday. Weather
conditions remain relatively stable before an increased moisture
reaches the area by Wednesday due to the proximity of a tropical
wave. Small craft should exercise caution today for areas of the
nearshore and offshore Atlantic waters due to increasing winds.
Seas up to 4 feet, occasionally up to 5 feet. Saharan dust
particles also promoting hazy conditions.

SHORT TERM...Today through Wednesday...

An overnight radar and satellite imagery analysis indicated that
clear to partly cloudy skies dominated the region. A few light
passing showers moved inland over the US Virgin Islands, Vieques,
Culebra, and eastern Puerto Rico, leaving minimal rainfall totals.
Reports from official sites indicate that overnight minimum
temperatures stayed above 80 degrees across coastal areas of the San
Juan metropolitan area, northeastern and southwestern Puerto Rico,
and the local islands. In higher elevations, temperatures dropped to
around 67-69 degrees. Winds were mainly light to calm and variable.

Weather conditions throughout the short-term forecast should remain
relatively stable, mainly due to consistent mid-level ridging across
the region and prolonged drier-than-normal periods. East-to-east-
southeast trade winds will persist throughout most of the forecast
period, with peak daytime wind speeds ranging from 15 to 20 mph,
driven by a high-pressure system over the central Atlantic. Winds
will begin to weaken and slowly turn from the east-northeast by
Wednesday night. Intermittent patches of drier- and wetter-than-
normal patches will cause precipitable water levels to fluctuate
between 1.6 and 2.0 inches today, followed by an abrupt drop to
around 1.3 inches on Tuesday afternoon and back to typical values on
Wednesday. Despite these moisture fluctuations, limited shower
activity is likely throughout the forecast period, primarily
generated by daytime heating over the far western-to-northwestern
sections of Puerto Rico. Passing shower frequency may increase by
Wednesday due to the proximity of a tropical wave. However, no
flooding impacts are anticipated with any of the expected rains.

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 Tuesday.

LONG TERM...Thursday through Monday...

Current model guidance suggests normal to below normal Precipitable
Water (PWAT) values as a tropical wave will be southwest of the
area to start the period. However, an area of normal to above
normal PWAT will start to approach the islands from the northeast
increasing PWAT values through Friday. This is due to the remnants
of a past frontal boundary being pushed towards the area by a
high pressure system over the Atlantic. High pressure aloft will
also strengthen over the Western Caribbean through the period.
Winds through Friday are forecast to be more east to east
northeasterly, which could bring some slight relief in terms of
warm temperatures although model guidance continues to suggest
above normal 925 mb temperatures. Winds are forecast, however, to
become more southeasterly by the weekend and through the rest of
the period. This will help promote warm temperatures once again.
PWAT values return to normal for the weekend with another plume of
moisture with above normal to normal values possibly reaching the
area by next week. Most available moisture will remain below 850
mb, with only a slight increase in moisture through the mid-levels
for the weekend. Saharan dust particles will linger to start the
forecast period.

AVIATION...

(06Z TAFS)

VFR conditions will likely prevail across all terminals during
the next 24 hours. Between 10/13 and 22Z, afternoon VCSH/SHRA may
briefly impact operations across TJSJ, TJBQ, and the USVI
terminals. Light to calm, variable winds will turn from the E-ESE
at 12-16 knots between 10/13-22Z, accompanied by higher gusts and
sea breeze variations.

MARINE...

A mid to upper level ridge is promoting generally stable conditions
across the local waters. Surface high pressure extending from the
northeastern to central Atlantic and north of the area will continue
to promote up to moderate to fresh east-southeasterly winds through
midweek. A tropical wave is expected to increase the potential for
showers and isolated thunderstorms mainly across the Caribbean waters
and local passages on Wednesday.

BEACH FORECAST...

Moderate risk of rip currents for most of St. Croix`s coasts
today and tonight. Moderate risk forecast for southwestern and
southeastern PR tonight. Low risk elsewhere.

&&

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

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

     Heat Advisory until 6 PM AST this evening for PRZ012-013.

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

     Heat Advisory until 6 PM AST this evening for VIZ001-002.

AM...None.
&&

$$
UPDATE...OMS
AVIATION...OMS