Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 250809
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
409 AM AST Thu May 25 2017

.SYNOPSIS...Broad surface high pressure will continue across the
Central Atlantic. SAL will linger through the end of the week.
Overall fair weather expected to continue through the weekend. An
upper level trough is forecast to move over the area by early
next week. A tropical wave is expected to enter the eastern
Caribbean by Tuesday.

&&

.SHORT TERM...Today through Saturday...
Partly cloudy skies prevailed across Puerto Rico and the U.S. Virgin
Islands overnight. Doppler radar detected some light showers mainly
across the coastal waters. A very dry airmass will continue to
dominate the local region for the next few days as an upper level
ridge continues dominating the region. Saharan dust will continue
across the region today. As a result, hazy skies can be expected.
Once again, A southeast wind flow will promote higher than normal
temperatures along the northern slopes of Puerto Rico this
afternoon. As a result, near record maximum temperatures can be
expected.

Upper level ridge will weaken by Friday. As a result, an increase in
moisture is expected for Friday and Saturday with a return to normal
weather conditions with shower and thunderstorm development expected
to occur across the interior and west sections of Puerto Rico
during the afternoons.

.LONG TERM...Sunday through Friday...
An upper level low and an associated trough to the east northeast
of the region is expected to drift northeastward while weakening
Sunday through early in the upcoming week. Another upper level
low and an associated trough is expected to develop over the
southwestern Atlantic early in the week, amplifying across the
northeast Caribbean Tuesday and Wednesday. Surface high pressure
across the central Atlantic is expected to maintain moderate
easterly trade winds across the region until early next week.
Winds are expected to become from the east to east northeast by
mid week and the from the east southeast for the rest of the
period. Optical Thickness model guidance suggests a relaxation in
the Saharan Air Layer across the region during the weekend and
for the upcoming week with only some particulates of dust
suspended in the air. Expect the continuation of a relatively dry
weather pattern across the local islands during the weekend with
only the typical diurnal induce afternoon shower activity over
western and interior PR. Latest surface analysis depicted a
tropical wave across the tropical Atlantic. This wave will
continue to move westward and approach to the Lesser Antilles
Sunday and Monday. It is then forecast to move over the eastern
Caribbean and over the local islands Tuesday through Wednesday.
This feature in combination with an upper trough should bring an
increase in tropical moisture transport and consequently increase
the chance for showers and thunderstorms over the local islands
and surrounding waters next week.

&&

.AVIATION...VFR conditions will prevail across all TAF sites through
at least 25/16z. VCSH can be expected across TJMZ and TJBQ with
mountain obscurations. Low level winds will be mainly southeast at
10 to 15 kts with higher gusts.

&&

.MARINE...
Long period northeasterly swell of 4 to 5 feet will continue to
affect the Atlantic waters and passages through late tonight.
There is a high risk of rip current for northwest through
north central and San Juan and vicinity beaches.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  90  78  89  77 /  10  10  40  40
STT  90  78  87  77 /  10  10  40  40

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk through this afternoon for North Central-
     Northwest-San Juan and Vicinity-Western Interior.

VI...None.
AM...None.
&&

$$

SHORT TERM...FC
LONG TERM....JF



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