Area Forecast Discussion
Issued by NWS San Juan, PR
FXCA62 TJSJ 300901
Area Forecast Discussion
National Weather Service San Juan PR
501 AM AST SAT JUL 30 2016
.SYNOPSIS...Subsidence ahead of the strong tropical wave near the
Lesser Antilles will generate a more stable and drier conditions
across the local islands today. The strong tropical wave located
around 52 west this morning is expected to move quickly to the
west across the Lesser Antilles and the Eastern Caribbean today
and reach the local region late tonight and Sunday. Showers,
thunderstorms and gusty winds will create hazardous marine
conditions across the regional waters beginning this afternoon.
.DISCUSSION...Doppler weather radar indicated isolated to
scattered showers mostly across the surrounding coastal waters
overnight and early this morning, with some of them affecting the
eastern sections of Puerto Rico from time to time. A strong
tropical around 52 West this morning will continue to move
rapidly to the west or west northwest today. The subsidence
pattern associated with this feature is expected to produce drier
air across the local islands today. Latest satellite images
depicted this dry air just across the USVI this morning.
Our attention today is focus on a strong tropical wave which is
located about 850 miles east of the Lesser Antilles early this
morning. The wave is moving westward rapidly, at 25-30 mph.
Regardless of development this system will likely bring showers,
thunderstorms and possible gusty winds across portions of the
USVI and Puerto Rico. At this forward speed and accordingly to the
global models, the leading edge of the system is expected to reach
the USVI late tonight and Puerto Rico on Sunday. Numerous showers
and scattered thunderstorms are forecast for Sunday as the
tropical wave moves across the local islands. The large moisture
envelope associated with the wave will continue over the area
through Monday so there is still a good chance of showers and
thunderstorms on Monday. Drier air is expected to moves across the
region behind the wave on Tuesday, before another tropical wave
reach the region Thursday and Friday, next week.
.AVIATION...VFR conditions expected today across most of the
local flying area. Periods of SHRA with OCNL VCSH expected for
TJSJ until 30/14Z. Increasing winds are expected today. After
30/16z shra will develop western and interior PR and along
Cordillera Central west of TJPS and moving WSW. Mtn obscurations
after there 30/17Z. MVFR to bcm likely after 30/18z at TNCM/TKPK
due to apchg trop wave and sct SHRA/TSRA.
.MARINE...Seas up to 6 feet and winds up to 20 knots are expected
this morning. Seas are expected to become hazardous this afternoon
across the offshore Atlantic waters and Anegada passage, then
spread across the offshore Caribbean waters, offshore Western
waters, the nearshore Atlantic waters and the waters surrounding
the USVI by tonight. A small craft advisory will go into effect
.PRELIMINARY POINT TEMPS/POPS...
SJU 90 80 86 76 / 30 70 70 30
STT 92 80 86 77 / 30 70 70 30
PR...VI...Small Craft Advisory from 8 PM this evening to 8 PM AST Sunday
for St.Thomas...St. John.. and Adjacent Islands.
AM...Small Craft Advisory from 2 PM this afternoon to 8 PM AST Sunday
for Anegada Passage Southward to 17N-Atlantic Waters of
Puerto Rico and USVI from 10 NM to 19.5N.
Small Craft Advisory from 8 PM this evening to 8 PM AST Sunday
for Caribbean Waters of Puerto Rico from 10 NM to 17N-
Coastal Waters of Northern USVI and Culebra out 10 NM-
Coastal Waters of Southern USVI Vieques and Eastern Puerto
Rico out 10 NM-Mona Passage Southward to 17N.
Small Craft Advisory from 2 AM to 8 PM AST Sunday for Coastal
Waters of Northern Puerto Rico out 10 NM.