Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 040103
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
903 PM AST TUE MAY 3 2016

.UPDATE...UNDER WEAKENING TROUGH AND AVAILABLE LOW LEVEL MOISTURE...
CONTINUE TO EXPECT SHOWER ACTIVITY ACROSS THE LOCAL WATER OVERNIGHT...
WITH A FEW OF THEM REACHING USVI AND E PR. RIDGE ALOFT WILL THEN
HOLD ACROSS THE AREA WEDNESDAY AND THURSDAY...BUT IS NOT STRONG
ENOUGH TO SUPPRESS SHOWER AND THUNDER ACTIVITY OVER AND NORTH OF
THE CORDILLERA EACH AFTERNOON. TROFINESS WILL RETURN TO THE
FORECAST AREA LATE THIS WEEK.

&&

.AVIATION...BRIEF PERIODS OF MVFR CONDITIONS IN SHRA TO PREVAIL
ACROSS THE LEEWARD ISLANDS TAF SITES AS WELL AS ACROSS TISX...TIST
AND TJSJ OVERNIGHT. ELSEWHERE ACROSS THE LOCAL FLYING AREA VCSH ARE
EXPECTED. SFC WINDS ESE AT AROUND 10 KNOTS OVERNIGHT INCREASING TO
10 TO 15 KNOTS BY 04/13Z.

&&

.MARINE...TRANQUIL MARINE CONDITIONS EXPECTED DURING THE NEXT FEW
DAYS...WITH SEAS UP TO 5 FEET AND WINDS AROUND 15 KNOTS. SEAS AND
WINDS LOCALLY HIGHER IN THUNDERSTORMS.

&&

.PREV DISCUSSION... /ISSUED /

SYNOPSIS...UPPER LEVEL TROUGH LOCATED OVER PUERTO RICO IS
ENHANCING SOMEWHAT THE INSTABILITY OVER PUERTO RICO AND
THE U.S. VIRGIN ISLANDS TODAY. THE TROUGH ALOFT WILL WEAKEN
AS LIFTS NORTHEAST ON WEDNESDAY. MID-UPPER LEVEL RIDGE WILL
MOVE OVER THE REGION BETWEEN WEDNESDAY AND THURSDAY...LIMITING
THE COVERAGE AND INTENSITY OF THE SHOWERS. SURFACE HIGH PRESSURE
OVER THE CENTRAL ATLANTIC WILL MAINTAIN A GENERALLY MOIST
SOUTHEASTERLY FLOW ACROSS THE LOCAL ISLANDS THROUGH THE WEEKEND.

DISCUSSION...CONVECTIVE INSTABILITY ASSOCIATED WITH AN UPPER
TROUGH OVER PUERTO RICO HAS RESULTED IN THE DEVELOPMENT SHOWERS
AND ISOLATED THUNDERSTORMS OVER PORTIONS OF THE NORTH CENTRAL AND
NORTHWEST PUERTO RICO THIS AFTERNOON. ADDITIONAL SHOWERS WILL
DEVELOP ACROSS THESE AREAS THROUGH AT LEAST LATE THIS AFTERNOON.

OPERATIONAL MODELS NOW SUGGEST THAT THE WEATHER CONDITIONS WILL
IMPROVE GRADUALLY THROUGH THURSDAY. AS UPPER TROUGH WEAKENS AND
SOME DRY AIR WILL FILTER IN AT MID LEVELS. THE CONVECTIVE
INSTABILITY WILL LIKELY DECREASE OVER THE LOCAL AREA. ALTHOUGH...
SHOWERS AND THUNDERSTORMS ARE STILL EXPECTED OVER THE NORTHWEST
QUADRANT OF PR EACH AFTERNOON...THE SHOWER AND THUNDERSTORM
COVERAGE WILL DECREASE OVER THE NEXT FEW DAYS. MAX TEMPERATURES
WILL INCREASE SOMEWHAT ACROSS THE LOCAL ISLANDS AS SOUTHEASTERLY
FLOW AND LESS CLOUDINESS ARE EXPECTED OVER THE NEXT COUPLE OF
DAYS. MAX TEMPS WILL RANGE FROM THE UPPER 80S TO LOW 90S...
ESPECIALLY ALONG THE NORTH COASTAL PLAINS.

FROM FRIDAY INTO THE WEEKEND...A POLAR TROUGH WILL DOMINATE
THE WESTERN ATLANTIC. AT THIS TIME...LOOKS LIKE THE ORGANIZED
CONVECTION WILL REMAIN WEST AND NORTH OF THE LOCAL AREA.

AVIATION...SHRA AND VCTS IN/AROUND TJBQ/TJMZ AND MOUNTAIN
OBSCURATION ACROSS INTERIOR AND NW SECTION OF PR AFTER 03/18Z.
SFC WINDS ESE 5 TO 15 KT WITH HIGHER GUSTS NEAR TSRA.

MARINE...WINDS OF 5 TO 15 KNOTS AND SEAS OF 3 TO 5 FEET
RESPECTIVELY. NO SMALL CRAFT ADVISORIES ARE ANTICIPATED OVER THE
NEXT 5-7 DAYS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  74  87  76  90 /  30  30  20  50
STT  75  85  78  85 /  20  20  20  30

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...NONE.
VI...NONE.
AM...NONE.
&&

$$

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