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000
FXCA62 TJSJ 210933
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
533 AM AST TUE MAY 21 2013

.SYNOPSIS...SURFACE HIGH PRESSURE NORTH NORTHEAST OF THE AREA IS
EXPECTED TO STRENGTHENS...MAINTAINING A MODERATE TO FRESH TRADE WIND
FLOW OVER THE REGION UNTIL THE UPCOMING WEEKEND. A WEAK TROPICAL
WAVE WILL MOVE SOUTH OF THE REGION ACROSS THE CARIBBEAN WATERS
TODAY AND TONIGHT. SEVERAL UPPER LEVEL PERTURBATIONS WILL MOVE
OCCASIONALLY ACROSS THE LOCAL ISLANDS DURING THE NEXT SEVERAL DAYS
INCREASING THE CLOUDINESS AND SHOWERS ACROSS THE FA.

&&

.DISCUSSION...LATEST SATELLITE IMAGES AND DOPPLER RADAR OBSERVATIONS
OVERNIGHT AND EARLY THIS MORNING...DEPICTED SCATTERED SHOWERS AND A
FEW THUNDERSTORMS MOVING WESTWARD ACROSS VIEQUES...CULEBRA...THE
USVI AND ACROSS THE CARIBBEAN WATERS. FEW OF THESE SHOWERS ALSO
AFFECTED THE EASTERN AND NORTHERN SECTIONS OF PUERTO RICO...BUT
THE TOTAL RAINFALL AMOUNTS SO FAR WERE GENERALLY MINIMAL. THIS
ACTIVITY WAS ASSOCIATED WITH A WEAK TROPICAL WAVE MOVING WESTWARD
ACROSS THE CARIBBEAN WATERS...SOUTH OF THE REGION. THIS FEATURE
IS EXPECTED TO COMBINE THIS AFTERNOON WITH DAYTIME HEATING AND
LOCAL EFFECT TOP PRODUCE SHOWERS AND THUNDERSTORMS MAINLY ACROSS
WESTERN AND INTERIOR SECTIONS OF THE ISLAND.

THE STRENGTHENING SURFACE HIGH PRESSURE...NORTH NORTHEAST OF THE
REGION...IS EXPECTED TO MAINTAIN AN EASTERLY TRADE WIND FLOW
ACROSS THE REGION FOR THE REST OF THE WORK WEEK. THIS FEATURE WILL
TIGHTENS THE LOCAL PRESSURE GRADIENT...INCREASING THE WINDS FLOW
ACROSS THE REGION. AS THIS HAPPENS...EMBEDDED MOISTURE IN THE
EASTERLY TRADES WILL CROSS THE REGION OCCASIONALLY FOR THE NEXT
FEW DAY. THIS MOISTURE IN COMBINATION WITH SOME UPPER LEVEL
PERTURBATIONS APPROACHING TO THE REGION...WILL PROVIDE THE
NECESSARY DYNAMIC TO INDUCE ROUNDS OF SHOWERS AND THUNDERSTORMS
OVER EASTERN PUERTO RICO...VIEQUES...CULEBRA AND THE USVI
OVERNIGHT AND EARLY IN THE MORNINGS AND ACROSS WESTERN AND
INTERIOR SECTIONS OF PUERTO RICO EACH AFTERNOON. PWAT VALUES WILL
PREVAIL CLOSE TO 1.70 INCHES TODAY AND TONIGHT...BUT ARE EXPECTED
TO INCREASE STEADILY TO AROUND 2.00 INCHES LATE WEDNESDAY AND
THURSDAY AS A SURGE OF MOISTURE APPROACHES TO THE REGION. ANOTHER
EASTERLY WAVE...ALONG 40 WEST THIS MORNING...IS EXPECTED TO REACH
THE REGION BY THE UPCOMING WEEKEND. COMPUTER MODELS GUIDANCE ARE
CONSISTENT IN A WET PERIOD STARTING SATURDAY AND CONTINUING
THROUGHOUT EARLY NEXT WEEK. STAY TUNED.

&&

.AVIATION...VFR AT ALL TAF SITES EXCEPT IN PASSING SHRA/ISOLD TSRA OVR
COASTAL WATERS EN ROUTE BTW ERN PR AND THE USVI TIL 21/14Z. SCT-BKN
CLD LYRS BTW FL020-FL120 DURNG THE MORNING HOURS WITH BRIEF MTN TOP
OBSC ACROSS THE ERN SECTIONS OF THE CENTRAL MOUNTAIN RANGE OF PR.
L/LVL WIND FM 5-20 KT BLO FL150 BCMG W AND INCR W/HT ABV.

&&

.MARINE...AS WINDS INCREASE MARINE CONDITIONS WILL BEGIN TO
DETERIORATE STARTING TONIGHT THROUGH AT LEAST THURSDAY. FOR TODAY
WIND UP TO 21 KNOTS AND SEAS UP TO 6 FEET ARE EXPECTED.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  86  77  84  77 /  40  30  40  30
STT  87  77  87  77 /  30  40  40  50

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...NONE.
VI...NONE.
COASTAL WATERS...SMALL CRAFT ADVISORY FROM 3 PM WEDNESDAY TO 6 AM AST SATURDAY
     FOR ANEGADA PASSAGE SOUTHWARD TO 17N-CARIBBEAN WATERS OF
     PUERTO RICO FROM 10 NM TO 17N.

     SMALL CRAFT ADVISORY FROM 9 AM WEDNESDAY TO 6 AM AST SATURDAY
     FOR ATLC WATERS OF PUERTO RICO AND USVI FROM 10NM TO 19.5N.

     SMALL CRAFT ADVISORY FROM 3 AM TO 9 AM AST THURSDAY FOR MONA
     PASSAGE SOUTHWARD TO 17N.

     SMALL CRAFT ADVISORY FROM 3 PM THURSDAY TO MIDNIGHT AST THURSDAY
     NIGHT FOR MONA PASSAGE SOUTHWARD TO 17N.

&&

$$

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