Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Juan PR
304 PM AST Friday Jan 30 2015
Synopsis...weak surface trough will continue to exit the forecast
area through Saturday. Middle to upper level trough entering the western
Atlantic will move over the open Atlantic waters through the
weekend...with associated prefrontal shear line near our forecast
area. Surface high pressure then builds and tightens the pressure
Discussion...after showers ended this morning across the northern
coast of Puerto Rico. Sunny to partly cloudy skies prevailed until
early in the afternoon. As of 3 PM AST...scattered to numerous
showers were forming across the south and western sections of
Puerto Rico and an isolated thunderstorm could form.
Shower activity over the Atlantic waters associated to the surface
trough will reach from time to time the northern parts of the
islands as northeasterly winds push them on shore. As high
pressure settles and strengthens the subsidence cap a fair weather
pattern should prevail for much of next week. However...scattered
showers cant be ruled out during the weekend...again mainly on
the north coastal regions in the night and early morning and
interior and southwest during the afternoons.
Aviation...VFR conds will prevail at all taf sites with very brief
MVFR in rain showers...and some mountain obscurations in PR. Winds easterly up to
12 knots below 5 kft. Light and variable up to 15 kft. Winds at 38 kft
were measured at 100 knots from the west at 30/12z but are expected to
Marine...Small Craft Advisory in effect for the offshore Atlantic
waters as seas of 7 feet are expected through the overnight.
Preliminary point temps/pops...
sju 73 83 75 83 / 20 50 50 50
stt 76 84 77 84 / 20 50 50 50
Coastal waters...Small Craft Advisory until 6 am AST Saturday for Atlantic waters of
Puerto Rico and USVI from 10nm to 19.5n.