Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 190900

Area Forecast Discussion
National Weather Service San Juan PR
500 AM AST Fri Oct 19 2018

.SYNOPSIS...Fair weather conditions are expected through the
upcoming week with isolated passing showers possible across the
north coastal areas as well as locally induced afternoon showers
across the western tip of Puerto Rico.


.SHORT TERM...Today through Sunday...

Trade wind showers across the regional waters affected portions
of the northern and eastern half of Puerto Rico through the
overnight hours. This activity is expected to continue through
the morning hours. Rainfall accumulations are expected to be
less than a tenth of an inch of rain. Breezy northeast winds will
continue through the short term period. Normal to just below
normal daytime temperatures are expected once again today, mainly
across the northern sections of the islands.

A mid to upper level ridge will continue to build over the
southwestern Atlantic into the local area through the short term
period. This will continue to promote drier air aloft. Upper level
trough northeast of the Leeward islands and associated induced
surface trough will remain east of the forecast area. However,
under a brisk northeast steering wind flow, passing showers and
enough low level moisture will continue to stream across the
region. Diurnally induced afternoon showers are expected to
develop mainly over the southwestern quadrant of PR each day.

.LONG TERM...Monday through Saturday...

A mid level ridge will hold across the local isles much of the
forecast cycle. At lower levels, a moderate to locally fresh east
northeast wind flow will prevail through at least early the
upcoming workweek, becoming east southeast at less than 10 knots
by Wednesday afternoon. Latest guidance continues to indicate PW
values below the normal range, which is 1.90 inches, Monday
through Friday. At this time, the best moisture advection is
expected Saturday onwards as a surface low develops over the
western Atlantic.

Under the aforementioned pattern, expect fair weather conditions
across most of the local islands with a few passing showers
possible across the north and east coastal areas of Puerto Rico
as well as the northern USVI and locally induced afternoon
showers across the western tip of Puerto Rico Mon-Tue. However,
as the prevailing wind flow diminishes, the chance for showers
and thunderstorms will increase across central and west Puerto
Rico Wed-Fri due to sea breeze convergence. Intensity and areal
coverage of showers and thunderstorms possible to increase Sat-


.AVIATION...Mainly VFR conditions are expected to prevail across
all terminals during the next 24 hours. Trade wind showers across
the regional waters could briefly move over the USVI/northern PR
terminals. SHRA is expected to develop over the SW quadrant of PR
btw 16z-22z, this may cause VCSH at JPS/JMZ. Winds will continue
from the northeast between 15-25 kt.


.MARINE...Choppy seas to continue during the next few days with
seas 4 to 6 feet and ENE winds of 15 to 20 kts. Therefore, small
boat operators are urged to exercise caution.


SJU  87  77  87  77 /  40  50  50  20
STT  87  78  87  78 /  40  50  50  30




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