Area forecast discussion
National Weather Service San Juan PR
1059 PM AST Monday may 20 2013
Update...partly cloudy skies have prevailed across the local
region tonight. Only light passing showers were noted mainly
across the coastal waters. No changes needed to forecast grids
tonight...as forecast is on track with ongoing weather situation.
&&
Aviation...VFR conditions will prevail across all taf sites
through at least 21/12z.
&&
Marine...seas of 5 feet or less and winds of 21 knots or less are
expected. Small craft should exercise caution across most of
coastal waters.
&&
Previous discussion... /issued 246 PM AST Monday may 20 2013/
Synopsis...a moderate to fresh trade wind flow will continue to
prevail across the local islands and regional waters as a surface
high pressure dominates the central Atlantic. Weak short wave
trough will continue to move across the local area tonight. Upper
level perturbations are expected to stream across the forecast
area over the next few days.
Discussion...as expected...skies were mostly sunny across Puerto
Rico...Culebra and Vieques early this morning...becoming partly to
variably cloudy in the afternoon. Across the U.S. Virgin Islands...
partly cloudy skies prevailed throughout the day. Scattered showers
and isolated thunderstorms were also noted across portions of
western Puerto Rico.
A gradual increase in low level moisture and favorable upper level
dynamics is expected Tuesday through Thursday...as upper level
perturbations stream across the local area. This will result in a
better chance of shower and thunderstorm activity across the forecast
area. As a result...under the prevailing easterly wind flow...expect
the continued trend of passing showers across the east coastal sections
of the islands especially during the morning hours...followed by
afternoon convection which will be mainly focused across the Cordillera
Central and western Puerto Rico Tuesday through at least Friday. Model
guidance continued to indicate an easterly wave reaching the local
islands by the upcoming weekend.
Aviation...continue VFR all taf sites xcpt in rain showers/thunderstorms and rain next few hours
at tjmz along with some obscure mountains across western Cordillera. VFR
overnight all sites except stray brief rain showers. Low level wind east 10-20 knots below
fl100 becoming west increase speed above.
Marine...seas up to 5 feet and winds of 21 knots or less expected
through Tuesday. Small boat operators should exercise caution
across most of the local waters.
&&
Preliminary point temps/pops...
sju 78 86 78 86 / 30 40 30 40
stt 77 87 77 87 / 30 30 40 40
&&
Sju watches/warnings/advisories...
PR...none.
Vi...none.
Coastal waters...none.
&&
$$
71/10
