Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 242100

Area Forecast Discussion
National Weather Service San Juan PR
500 PM AST Wed May 24 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 Friday...
Hazy skies and hot temperatures were observed today across the
forecast area. A few clouds developed over the mountains and
northwest portions of PR during the afternoon hours, however no
significant rainfall was detected over land areas. The temperature
at the international airport in San Juan reached 93 degrees, this
tied the record set in 1990.

Limited shower activity is expected to continue across the
islands. Saharan air layer will continue to result in hazy skies
and dry mid levels. Above normal temperatures will continue
through the short term period. A slight increase in moisture is
expected on Friday afternoon, this moisture in combination with
diurnal effects will lead to better chances for showers across the
islands. However, no significant rainfall amounts are expected at
the moment.

.LONG TERM/from previous discussion...Saturday through
An upper level low and an associated trough is forecast to
develop just to the east northeast of the region during the
upcoming weekend. This feature is expected to erode the mid to
upper level ridge that persisted over the region for the last few
days. However, the upper trough axis is forecast to remain east of
the region, maintaining the islands on the subsidence side of the
trough. Surface high pressure across the central Atlantic is
expected to maintain moderate easterly trade winds across the
region until early next week. Optical Thickness model guidance
suggests that the Saharan Air Layer will persist over the region
through most of the work week and into the upcoming weekend,
resulting in hazy and a relatively dry airmass across the local
islands. Latest surface analysis depicted a tropical wave across
the tropical Atlantic. This wave will continue to move westward
and approach to the Lesser Antilles late Monday and Tuesday. It is
then forecast to move over the eastern Caribbean and over the
local islands Tuesday through Wednesday. This feature 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...Mainly VFR conditions will prevail during the next 24
hours. Surface winds E-ESE at 10-15 knots. Light and variable
overnight. HZ due to Saharan dust will continue but vsby should
remain P6SM.


.MARINE...San Juan and Rincon buoys were indicating a 13-14 second
northeasterly swell at 3-4 feet during the last couple of hours.
Winds are near 15 knots from the east with some gusts in the low
20s. A high rip current risk is in effect for the northern beaches
of Puerto Rico and Culebra through Thursday. Northerly swell will
peak overnight.


SJU  78  89  77  88 /  10  10  10  20
STT  79  89  78  87 /  10  10  20  40


PR...High Rip Current Risk through late tonight for Culebra-Northeast-

     High Rip Current Risk through Thursday afternoon for North
     Central-Northwest-San Juan and Vicinity-Western Interior.



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