Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 250910

Area Forecast Discussion
National Weather Service San Juan PR
510 AM AST Sun Jun 25 2017

.SYNOPSIS...Trade wind showers across windward areas during the
morning hours, followed by a few afternoon showers across west
sections of Puerto Rico are expected today. The chance for showers
and thunderstorms will increase across the local isles late
tonight and into early Monday as a tropical wave moves across the
eastern Caribbean. A drier and dusty air mass is expected Tue-Wed
with afternoon convection still possible. Another wave passage is
expected late during the workweek.


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

A surface high pressure will continue to dominate the local
region through the weekend. Under this wind
showers will reach the local islands at times. A tropical wave is
forecast to affect the local region between Sunday night into
Monday morning. As a result, an increase in cloudiness with
showers and thunderstorms are expected across Puerto Rico and the
U.S. Virgin Islands. This wave will move quickly and is expected
to exit the local area by Monday afternoon. After the passage of
this wave, a very dry airmass will encompass the region with a
dense area of Saharan dust affecting the local area. Hazy
conditions and limited shower activity activity is expected by

.LONG TERM...Wednesday through Monday...

A drier and dusty air mass is expected to prevail across the
local islands Wednesday through early Thursday with limited
shower and thunder development across west sections of Puerto
Rico in the afternoon. Elsewhere, fair weather with hazy skies
will prevail. Moisture is expected to increase across the forecast
area Thursday morning as an easterly disturbance reaches the
forecast area. In fact, latest guidance suggested plenty of
moisture to persist through at least the weekend. This will assure
at least passing showers with isolated thunderstorms across
windward areas as well as locally induced showers and thunderstorms
across the interior and west sections of Puerto Rico during the
afternoon hours.


.AVIATION...VFR conditions will prevail across all TAF sites through
25/16Z. Brief periods of MVFR conditions can be expected across TJMZ
and TJBQ from 25/16z through 25/22Z. Low level winds will be mainly
east southeast at 10 to 15 kts.


.MARINE...Tranquil marine conditions are expected to prevail today
across the local waters. However, winds are expected to slightly
increase tonight into Monday as a tropical wave moves across the
eastern Caribbean.


SJU  90  79  89  79 /  20  40  40  20
STT  90  79  89  79 /  20  50  50  20




LONG TERM....OM is the U.S. government's official web portal to all federal, state and local government web resources and services.