National Weather Service San Juan PR
406 PM AST Mon May 14 2018
.SYNOPSIS...Upper ridge is forecast to prevail through Tuesday. Short
wave trof is expected to briefly move from the west on Wednesday.
Tutt establish northeast of the region during the second part of the
week. At the surface, broad surface high will continue in place
through the long term period. A weak easterly perturbation is
forecast to move late in the weekend or by early next week, mainly
south of the region.
&&
.SHORT TERM...Today through Wednesday...
The combination of the available moisture with local effect will
continue to produce afternoon showers across the northwest
quadrant of Puerto Rico. Rainfall accumulation will range between
half and three quarter of an inch. A few showers could develop
downwind from el Yunque into the San Juan metro area and across
the surrounding waters of the U.S. Virgin Islands through this
evening. Passing low level clouds and trade wind showers would be
possible overnight across the eastern half of PR and the U.S.
Virgin Islands.
A similar weather pattern is expected Tuesday and Wednesday.
Although no significant rainfall amounts are expected through the
forecast period, patches of low level moisture combined with low
level convergence will result in passing showers across the
windward sections of Puerto Rico and the U.S. Virgin Islands each
night and morning hours. Followed by locally induced showers each
afternoon over the west interior of PR Tuesday and Wednesday.
.LONG TERM...Thursday through Tuesday...
Tutt northeast of the region is forecast to remain in place through
the long term period. Guidance suggest that a weak easterly wave or
tutt induced perturbation, is forecast to move mainly south of the
islands across the Caribbean waters by Sunday or Monday. However,
the local area is expected to remain under the convergent side of
the tutt and this will inhibit the potential for widespread
convection over the islands. Meanwhile, at the surface a broad
surface high pressure will continue to bring patches of low level
clouds and passing showers through the long term period. Showers
should develop each afternoon due to the combination of the
available low level moisture, day time heating, sea breeze
convergence and orographic effect. Mainly over the western sections
of Puerto Rico and downwind of the smaller islands.
&&
.AVIATION...VFR conditions expected throughout the forecast period.
But, showers will develop across the NW-PR producing brief periods
of MVFR conds at JMZ/JBQ btwn 14/17-23z. Most of the activity will
dissipate by this evening with just a few VCSH at
TJSJ/TIST/TISX/TCNM/TKPK. Winds ESE at 10 to 20 knots with higher
gusts and sea breezes along coastal areas. Winds are expected to
drop around 10 kt aft 14/23z.
&&
.MARINE...Choppy marine conditions continue across the regional
waters with seas up to 6 feet across the open waters and below 4
feet in nearshore and protected waters. Seas will build to 6-8
feet the second part of the week as winds increase to around 20
knots by midweek.
&&
.PRELIMINARY POINT TEMPS/POPS...
SJU 76 86 75 86 / 20 40 30 30
STT 75 87 76 86 / 50 50 30 30