Area Forecast Discussion
Issued by NWS San Juan, PR
FXCA62 TJSJ 270801
Area Forecast Discussion
National Weather Service San Juan PR
401 AM AST Mon Mar 27 2017
.SYNOPSIS...A surface low over the Atlantic waters northwest of
PR will continue to move north northeast into the western Atlantic for
the next few days. A surface high will build across the Western
Atlantic just northwest of the surface low, spreading into the
local area by midweek as the surface low moves east into the
central Atlantic. Drier air at mid levels is expected to continue
moving in through the end of the week. Light southerly winds will
continue until Monday, becoming very light on Tuesday, then
northerly and increasing on Wednesday and Thursday.
.SHORT TERM...Today through Wednesday...
Doppler weather radar indicated isolated to scattered showers
moving northward from the Caribbean waters across the U.S. Virgin
Islands, Vieques, Culebra as well as across the eastern sections
of Puerto Rico overnight and early this morning. However, no
significant rainfall amounts were measured. Elsewhere over land
areas not significant precipitation was detected.
A surface low pressure system to the north of Hispaniola this
morning will continue to bring a relatively moist southerly wind
flow across Puerto Rico and the U.S. Virgin Islands today. Less
cloud cover is expected today across the region and therefore
diurnal heating in combination with sea breeze convergence and
other local effects will induce the development of showers and
possible thunderstorms along and north of Cordillera Central,
including the San Juan Metro area during the afternoon hours.
Urban and small stream flooding are possible over northern Puerto
Rico. As the low moves further northeastward over the Atlantic
waters, moisture will continue to decrease across the local
islands tonight and Tuesday. However, the lingering moisture in
combination with local effects will induce the development of
some convection each afternoon specially across the interior and
northern sections of Puerto Rico. Due to the expected southerly
wind flow, warmer than normal temperatures are possible across
the northern coastal municipalities of Puerto Rico during the
next few days.
.LONG TERM...Thursday through Monday...
The surface low will continue to move north into the north
central Atlantic on Thursday and the ridge across the western
Atlantic builds north of the islands through the end of the week.
This will generate a northerly wind flow from Wednesday through at
least Saturday. A much drier airmass will prevail over the region
from Thursday through late Friday...this will result fair weather
conditions through this period. East to southeast winds return
from early Saturday through Sunday with moisture increasing from
the southeast...associated with remnants of the surface
.AVIATION...Brief periods of MVFR conds will remain possible at
the Leeward and USVI TAF sites this morning. SHRA/TSRA expected
aft 27/16z in and around TJMZ, TJBQ and TJSJ. Light and variable
winds are expected overnight. Latest TJSJ sounding indicated a
south southwesterly wind flow at all levels, but very strong
.MARINE...Seas will continue to subside this morning. Early this
morning local buoy 41115 in Rincon indicated seas of 5 feet while
bouy 41053 in San Juan indicated also seas of 5 feet. The small
craft advisories were cancelled. A moderate risk of rip currents
will continue to prevail across some areas during the next few
.PRELIMINARY POINT TEMPS/POPS...
SJU 88 75 86 77 / 60 40 40 10
STT 84 75 84 75 / 40 40 40 20
PR...High Rip Current Risk until 6 AM AST early this morning for
North Central-Northwest-San Juan and Vicinity-Western