Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 172102

Area Forecast Discussion
National Weather Service San Juan PR
502 PM AST Wed Jan 17 2018

A mid to upper level ridge continue as the dominant weather feature.
A surface high pressure across the Atlantic Ocean is inducing a
moderate trade wind flow which is pushing patches of low level
moisture from time to time. Under this pattern expect passing
showers across the U.S. Virgin Islands, east and north Puerto Rico
each day, as well as afternoon convection across west Puerto Rico.
A similar pattern will prevail through the end of the work-week.


Shower activity was noted across the west interior and western
Puerto Rico. Between a quarter of an inch to almost one inch of
rainfall fall across those areas. On the other hand the eastern
coastal sections observed quick passing showers, which developed
downwind from the U.S. Virgin Islands into Culebra and eastern
Puerto Rico.

Later tonight a patch of dry air will limit shower activity to
the north and eastern sections of Puerto Rico and downwind from
the U.S. Virgin Islands. Elsewhere mostly clear skies with no
shower activity is expected. By Thursday morning a patch of
moisture will increase the amount of showers across the eastern
half portion of Puerto Rico and the U.S. Virgin Islands. Showers
are then expected across the western portion of Puerto Rico during
the afternoon hours. The trade wind inversion is forecast to
prevail through the end of the work-week limiting any vertical
development across the islands. Therefore no lightning activity is

Saturday through Thursday...Upper level ridge will
build north of the area. As a result, dry and pleasant weather
conditions are expected Saturday and Sunday. For Monday next
week,forecast models indicated high pressure weaken and winds
shift southeasterly. Moisture is then forecast to increase at the
beginning of next week. no significant weather events are
forecast to affect the local region in the log term.


VFR conds expected across the local terminals through the
forecast period. VCSH expected for the local terminals with a
probability of TEMPO MVFR conds at TJMZ between 17/18Z and 17/21Z,
but most of the activity is expected south of TJMZ. Winds from
the east at around 10KT with sea breeze variations for the rest of
today, decreasing winds overnight.


Marine conditions are expected to slowly improve overnight. For
that reason small Craft advisories continues for many of the
local waters due to seas up to 7 feet. Model guidance are
suggesting the arrival of a northerly swell by the upcoming
weekend, which could increase the seas above 7 feet especially
across the Atlantic Waters and Caribbean Passages.

For the beach goers...High risk of rip currents still in effect
along the northern coastline of Puerto Rico and Saint Croix.


SJU  73  84  75  84 /  40  20  10  20
STT  74  84  74  84 /  50  20  10  10


PR...High Rip Current Risk through late tonight for North Central-
     Northeast-Northwest-San Juan and Vicinity-Southeast-Western

VI...High Rip Current Risk through late tonight for St Croix.

AM...Small Craft Advisory until 2 AM AST Thursday for Atlantic Waters
     of Puerto Rico and USVI from 10 NM to 19.5N-Coastal Waters
     of Northern Puerto Rico out 10 NM.



LONG TERM....Previous Forecast
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