Post by cycloneye on Dec 13, 2016 4:06:44 GMT -6
Area Forecast Discussion
National Weather Service San Juan PR
541 AM AST Tue Dec 13 2016
.SYNOPSIS...Mid to upper ridge across the Caribbean basin will
continue to dominate the local area through the end of the work
week. Ridge will slowly erode as polar trough press against it by
the end of the work week. Broad surface high pressure over the
the Central Atlantic will continue to promote fresh to locally
strong easterly winds through at least Wednesday. Prefrontal
boundary is forecast to reach the local area late Friday into
Saturday. Northeasterly trades expected to increase once again in
the weekend as another surface high enters the Western Atlantic.
&&
.DISCUSSION...Trade wind showers continued across the forecast
area through the overnight hours. The highest rainfall amounts
were observed at St. Thomas with just above a quarter of an inch
reported at the Cyril E. King airport. Some of these showers
affected briefly areas of eastern PR including Culebra. Similar
conditions are expected for the rest of the day. Breezy trades
carrying quick passing showers across the USVI and mainland PR.
Shallow afternoon shower development is possible across portions
of western PR, but rainfall no significant rainfall amounts are
forecast at the moment. This weather pattern should continue for
the next few days, with the driest day expected on Thursday.
By Friday into the weekend, cloudiness and shower activity is
forecast to increase across the local area as polar trough across
the Western Atlantic presses against the upper ridge and
prefrontal shearline moves north of the area. Meanwhile another
strong surface high pressure will enter the Western Atlantic
promoting fresh to locally strong northeasterly trade winds.
&&
.AVIATION...VFR conditions expected across most of the TAF sites
during the forecast period. SCT SHRA will move west across the
flying area today. Some of these SHRA will lead to brief MVFR conds
as they pass by. Mountain obscurations are possible along the
Cordillera Central. East winds of 15 to 25 kts will prevail below
FL200.
&&
.MARINE...Hazardous seas will continue across the regional waters
Today. Small craft advisories are in effect due to seas up to 8
feet. Easterly winds around 20 knots are expected across much of
the area. Winds and seas will slowly subside late in the work
week but increase once again during the weekend in response to a
strong surface high pressure entering the Western Atlantic. A
moderate to high risk of rip currents continues Today for most of
the beaches of the islands.
&&
.PRELIMINARY POINT TEMPS/POPS...
SJU 85 75 85 75 / 40 20 20 20
STT 85 76 85 75 / 40 20 30 20
&&