000
FXCA62 TJSJ 141920
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
320 PM AST FRI JUN 14 2013

.SYNOPSIS...BREEZY TRADE WINDS WILL CONTINUE TODAY...IN ASSOCIATION
WITH A TROPICAL WAVE AND A STRONG HIGH PRESSURE NORTHEAST OF THE
ISLANDS. THE WEAK TROPICAL WAVE WILL CONTINUE TO MOVE QUICKLY SOUTH
OF THE AREA WITHOUT AFFECTING DIRECTLY THE LOCAL ISLANDS. ANOTHER
PULSE OF MOISTURE WILL BRING SOME SHOWERS AND A FEW THUNDERSTORMS
ACROSS THE ISLANDS ON SATURDAY. WEATHER CONDITIONS WILL IMPROVE ON
SUNDAY WHEN AN AIR OF DRY AND STABLE AIR MASS MOVE OVER THE REGION.

&&

.DISCUSSION...A WEAK TROPICAL WAVE WILL CONTINUE TO MOVE AWAY FROM
THE REGION THE REST OF TODAY. SATELLITE BLENDED PWAT ANALYSIS AS
WELL AS THE GPS MET DATA HAVE SHOWED A RAPID DRY AIR ENTRAINMENT
FROM THE EAST. PRECIPITABLE WATER VALUES HAS DECREASED RAPIDLY SINCE
THIS MORNING FROM 2.14 INCHES TO 1.6 INCHES AT CHRISTIANSTED...ST
CROIX. THIS DRY AND STABLE AIR MASS WILL CONTINUE TO SPREAD OVER
MAINLAND PUERTO RICO DURING THE REST OF THE AFTERNOON HOURS AND
PERSIST UNTIL AROUND 15/06Z WHEN ANOTHER PULSE OF MOIST AIR IS
FORECAST TO MOVE OVER THE ISLANDS FROM THE SOUTHEAST. THE SUBEQUATORIAL
RIDGE LOCATED OVER THE LEEWARD ISLANDS IN COMBINATION WITH DRY AIR
ADVECTION FROM THE EAST HAVE INHIBITED THE DEVELOPMENT OF SHOWERS
AND THUNDERSTORMS ACROSS THE AREA TODAY. ANOTHER FACTOR THAT HELP
TO INHIBIT SHOWER DEVELOPMENT IS THE FAIRLY STRONG LLVL FLOW THAT
DELAY THE SEA BREEZE FORMATION OVER WESTERN PUERTO RICO. FOR THE
REST OF TODAY...EXPECT LITTLE SHOWER ACTIVITY...IF ANY...DEVELOPING
OVER NORTHWESTERN PUERTO RICO LATE THIS AFTERNOON. THEN...A PULSE
OF MOIST AIR WILL BRING SOME CLOUDS AND A FEW SHOWERS ACROSS EASTERN
PUERTO RICO SATURDAY MORNING...FOLLOWING BY SOME AFTERNOON CONVECTION
OVER WESTERN PUERTO RICO SATURDAY AFTERNOON. THE DRY AND STABLE CONDITIONS
WILL RETURN ON SUNDAY AS A BIG AREA OF DRY AIR WITH SAHARAN DUST WILL
ENCOMPASS THE FORECAST AREA. THIS STABLE WEATHER PATTERN WILL PERSIST
UNTIL AT LEAST TUESDAY.

&&

.AVIATION...XPCT SHRA/TSRA THIS AFTERNOON NW PR WI PSBL MVFR/IFR
COND TJMZ/TJBQ AND MTN OBSC. VFR CONT ELSEWHERE WITH ISOLD SHRA.
WIND BLO FL100 ESE-SE 15-27 KT THRU SAT.

&&

.MARINE...SCA CONTINUES IN EFFECT ACROSS THE OFFSHORE WATERS UNTIL
SAT EVENING DUE TO SEAS OF AROUND 7 FT. ELSEWHERE...SMALL CRAFT
OPERATORS SHOULD EXERCISE CAUTION DUE TO SEAS OF 6 FT OR LESS AND
WINDS BTWN 15-20 KT.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  78  88  78  88 /  20  20   0  20
STT  79  88  80  89 /  30  30  20  20

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...NONE.
VI...NONE.
COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 6 PM AST SATURDAY FOR ATLC WATERS OF
PUERTO RICO AND USVI FROM 10NM TO 19.5N.

&&

$$

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