Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 190842 CCA

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
442 AM AST Mon Mar 19 2018

.SYNOPSIS...A weak shear line remains to the northeast of Puerto
Rico as a result showers with isolated thunder will be
possible today. A ridge will build across the local area on
Tuesday, which will promote fair weather conditions with an
occasional shower until early Thursday. Late Thursday will be a
transition day for most of the region due to an approaching cold
front that will create unsettled weather through the weekend.


SHORT TERM...Today through Wednesday...
A ridge near the Bahamas and the remnants of a shear line to the
north of the islands will linger around through at least Tuesday.
Under this pattern, patches of moisture will move across the islands
from time to time. Light southerly winds will aid in sea breeze
formation today. This combined with diurnal heating and the presence
of a jet segment aloft will result in scattered to locally numerous
afternoon showers across the Cordillera Central, north and west
Puerto Rico. Shower formation in the form of streamers is possible
downwind from the U.S. Virgin Islands by mid morning into the
afternoon hours.

As a ridge pattern builds, moisture will erodes and shower activity
is expected to be limited Tuesday and Wednesday. But, shower
activity will remain possible across the USVI and eastern sections
of PR during the night time diminishing during the morning hours.
Sea breezes and diurnal heating would be the driver mechanisms
for afternoon convection each day. By Wednesday, easterly winds at
10 to 15 mph are expected to return as a high pressures across
the Western Atlantic tighten the local pressure gradient.

.LONG TERM...Thursday through Tuesday...
Thursday, A vertical stacked ridge will promote fair weather
earlier on Thursday but, the ridging will begin to weak late in
the day due to an approaching cold front. East southeast winds
will carry warm moist tropical air over the islands late in the
day, as result isolated to numerous showers will be possible
across the northern coast of Puerto Rico during the evening.

Friday, a col will form to the northeast of Puerto Rico as a cold
front continues to make its way closer to Puerto Rico with showers
and east northeast winds.

Saturday-Monday, Currently model guidance is showing a frontal
passage on late Sunday or early Monday. A prevailing east
northeast wind flow, upper level instability combined with low
level moisture will keep the islands in an unsettled pattern with
showers mainly during the morning and afternoon.

Tuesday, Winds will remain out of the east northeast with patches
of low level moisture moving across the islands as the surface
and mid level ridge tries to reestablish itself over the local


.AVIATION...VFR conds are expected to prevail through 19/17Z. SHRA
are posible in NW and north central PR between 19/17-23z with brief
MVFR conds and mtn obsc. VCTS were included at TJBQ and TJMZ, where
is possible to form. Passing shower are expected at TJPS/TISX aft
19/23Z. Sfc winds will be calm to light and vrb becoming from the SE
at 10 kt and with sea breeze variations aft 19/14Z.


.MARINE...Seas 3 to 5 feet with an east to southeast winds 5 - 10
kts. Seas will remain around 3 to 5 feet across all local waters
ways through Wednesday. There`s a High Rip Currents risk for
northern beaches of Puerto Rico until Wednesday.


SJU  86  75  86  75 /  20  20  20  20
STT  84  73  84  75 /  30  30  20  20




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