National Weather Service San Juan PR
500 AM AST Tue Apr 4 2017
.SYNOPSIS...Locally induced afternoon showers are expected
each day across west and northwest Puerto Rico with isolated
shower activity elsewhere. Expect warmer temperatures by the end
of the workweek mainly along the northern slopes of Puerto Rico
under east southeast winds. A wetter pattern possible early next
week.
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.SHORT TERM...Today through Thursday...
The Doppler Radar detected shower activity moving across the Eastern
Municipalities of Puerto Rico and across the surrounding waters of
St Croix, with some of them moving inland at times. Most of the
showers dissipated overnight as a drier air mass moved across the
islands.
Under a ridge pattern and below normal moisture continue to expect
mostly sunny to partly cloudy skies with no shower activity across
most of the islands. However, passing showers from time to time
cannot be ruled out this morning across the windward sections of
Puerto Rico and the U.S. Virgin Islands. Then, showers are expected
to develop downwind from the U.S. Virgin Islands into the eastern
sections of Puerto Rico late in the morning and early afternoon.
Afternoon convection is expected to develop across the interior and
western sections of Puerto Rico due to the diurnal heating and sea
breeze variations. Most of this activity is forecast to dissipate
around sunset. The potential for urban and small stream flooding is
present for the municipalities of the west interior and western
Puerto Rico during the afternoon hours.
In general, a fair weather pattern is expected due to the mid to
upper level ridge at least until mid-week. However moisture
advection will result in passing showers across the windward
sections during the overnight and early morning hours. Then, the
combination of the local effects and available moisture will result
in afternoon convection across the interior and west portions of
Puerto Rico and downwind from the U.S. Virgin Islands each day.
.LONG TERM...Friday afternoon through Wednesday...
As a surface high north of the local islands shifts eastward, low
level winds will become east southeast by Friday and into the
upcoming weekend. At upper levels, a ridge pattern will hold
across the forecast area through the end of the workweek. The
ridge aloft is then forecast to erode Friday and into the upcoming
weekend as a broad mid to upper level trough moves across the
western Atlantic. This feature is expected to amplify into the
central and eastern Caribbean early next week with its associated
surface front/low level moisture lingering across the forecast
area through at least midweek next week. Therefore, based on the
latest guidance, a wetter pattern is possible early next week
under trofiness aloft and moisture associated with the lingering
boundary. Meanwhile, Wednesday Afternoon through at least Friday
continue to expect a seasonable weather pattern with locally
induced afternoon showers across west and northwest sections of
Puerto Rico. As the ridge aloft collapses during the weekend,
there is a potential for afternoon thunderstorms Sat-Sun.
&&
.AVIATION...VFR conditions are expected during most of the FCST
PRD. However, mountain obsc and afternoon showers are expected
across the interior and west portions of PR. These activity could
impact TJMZ/TJBQ btwn 04/18-22z. MVFR/IFR ceiling are possible
during that period. Also, TJPS can expect SCT-BKN ceilings btwn
FL030-FL060 during the afternoon. Winds are expected from the E-NE
below 10 knots til 04/13z, increasing at 10 to 15 kts with gusts
btwn 20 and 30 kts.
&&
.MARINE...A moderate to fresh easterly wind flow will prevail
throughout the week, becoming east southeast by Friday as the
surface high north of the area shifts eastward. A distant low
pressure moving into the northern Atlantic will generate another
northerly swell which will arrive and spread across the local
Atlantic waters tonight. Seas 4 to 6 feet expected today increasing
5 to 7 feet by tonight. There is a moderate to high risk of rip
currents along the Atlantic shoreline of Puerto Rico, Culebra and
northern USVI.
&&
.PRELIMINARY POINT TEMPS/POPS...
SJU 86 77 87 76 / 20 30 30 10
STT 86 76 86 75 / 30 30 30 10
&&