Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 041804

Area Forecast Discussion
National Weather Service San Juan PR
204 PM AST Sun Dec 4 2016

A mid level ridge will limited the vertical development of showers
across the region. At low levels, a surface high pressure will
build over the Western Atlantic, pushing a frontal boundary to
the North and near the local waters. In addition, above normal
low level moisture is expected to pool over the islands. This
weather pattern will continue to bring trade wind showers across
the windward sections of the U.S. Virgin Islands and Puerto Rico
at times. In addition, expect locally induced afternoon showers
across the interior and west sections of Puerto Rico each day.


In general, a fair weather pattern prevailed today. Satellite
imagery detected mostly sunny skies with a thin layer of mid to
upper level clouds over the region. The Doppler Radar observed
little to no shower activity across the islands. However,
cloudiness and showers began to increase in coverage across the
interior, West and South PR, as well as streamers off of the U.S.
Virgin Islands early this afternoon. Therefore, this weather
conditions are expected to continue during the rest of the
afternoon, with the strongest activity over the interior and
southwestern portions of Puerto Rico.

The upper level ridge pattern is forecast to slowly erode, as a
low pressure moves over the region from the east. A high pressure
at mid levels is expected to hold aloft during this week.
Also, a frontal boundary is forecast to moves to the North and
near the local region. The proximity of this frontal boundary,
plenty of surface moisture and under the prevailing northeasterly
wind flow the chance of early morning cloudiness and quick passing
showers along the north and east coastal section of the islands
are likely each day. Shallow afternoon convection is expected
mainly across the interior and west Puerto Rico, as well as
downwind from the U.S. Virgin Islands.


Mainly VFR conditions are expected across all terminals through
the forecast period. Showers across the Atlantic waters associated
to a frontal boundary could reach the northern/eastern terminals
of the islands on a 10-14 kt east to northeasterly steering wind
flow. Surface winds light and variable through the overnight


Tranquil marine conditions with seas around 3 feet and winds at 10
to 15 knots. A northerly swell is expected to reach the Atlantic
Waters and the Caribbean Passages Monday night into Tuesday.


SJU  77  87  76  86 /  20  20  40  40
STT  77  86  77  86 /  20  20  20  30




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