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000
FXCA62 TJSJ 240920
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
520 AM AST FRI MAY 24 2013

.SYNOPSIS...AT MID AND UPPER LEVELS...A WEAK SHORT WAVE IS MOVING
AWAY FROM THE AREA TO THE EAST AT UPPER LEVELS WHILE A STRONGER
LONG WAVE IS MOVING TOWARD THE ATLANTIC OCEAN FROM THE U.S.
MAINLAND AND WILL PUSH RIPPLES THROUGH THE LOCAL AREA UNTIL
TUESDAY IN MOSTLY WESTERLY...CYCLONIC FLOW. HIGH PRESSURE
DEVELOPS OVER THE CARIBBEAN MID WEEK...BUT LOW PRESSURE BEGINS
FORMING IN THE WESTERN ATLANTIC NEAR FLORIDA AND GEORGIA ON
WEDNESDAY BRINGING A SHIFT TO SOUTHWESTERLY FLOW LATER NEXT WEEK.

AT LOWER LEVELS...HIGH PRESSURE CONSOLIDATES IN THE NORTHERN
CENTRAL ATLANTIC DURING THE WEEKEND AND MAINTAINS VERY MOIST EAST
SOUTHEAST TRADE WIND FLOW THROUGH EARLY NEXT WEEK. A TROPICAL WAVE
CURRENTLY NEAR 42 WEST WILL PASS MAINLY SOUTH OF THE LOCAL AREA ON
MONDAY NIGHT FOLLOWED BY CONTINUED MOIST FLOW.

&&

.DISCUSSION...SHOWERS HAVE INCREASED IN THE CARIBBEAN BETWEEN
SAINT CROIX AND SAINT JOHN WHILE INDIVIDUAL CELLS ARE MOVING
TOWARD THE PUERTO RICO MAINLAND. SMALL SHOWERS HAVE BEEN PASSING
THROUGH EASTERN PUERTO RICO ALL NIGHT. THE MOISTENING TREND WILL
CONTINUE THROUGH THE DAY TODAY...BRINGING MOSTLY CLOUDY
SKIES...SHOWERS AND THUNDERSTORMS. WITH SOILS ALREADY SATURATED
AND RIVERS RUNNING SOMEWHAT ABOVE BASE FLOW...EXPECT THAT THERE
COULD BE FLOODING AND MUDSLIDES ONCE THE MAIN SURGE OF MOISTURE
ARRIVES IN PUERTO RICO...THEREFORE WILL ISSUE A FLASH FLOOD WATCH
FOR ALL OF PUERTO RICO AROUND 6 AM AST THIS MORNING AND ALLOW IT
TO EXTEND THROUGH SATURDAY. THE LATEST GFS MODEL FROM 24/00Z SHOWS
TODAY AS HAVING THE BEST AND MOST CONTINUOUS MOISTURE COLUMN OF
ANY DAY UNTIL NEXT THURSDAY. THIS DEEP SUPPORT WILL ALLOW
WIDESPREAD SHOWER ACTIVITY TO CONTINUE THROUGH THE DAY AND LINGER
THROUGH MUCH OF THE NIGHT TONIGHT. MOIST FLOW WILL CONTINUE THIS
SCENARIO THROUGH MUCH OF THE WEEKEND...ALTHOUGH THE GFS DID SHOW
SOME WEAKENING OF THE MOISTURE ON SUNDAY. SCATTERED SHOWERS WILL
CONTINUE THE WETTER THAN NORMAL PERIOD THROUGH MOST OF THE WEEK
NEXT WEEK WITH INCREASING MOISTURE AFTER MID WEEK. THE U.S. VIRGIN
ISLANDS HOWEVER SHOULD NOT SEE SUFFICIENT RAINFALL AMOUNTS FOR
SIGNIFICANT FLOODING ALTHOUGH SHOWERS WILL BE NUMEROUS.

THE ARRIVAL OF THE TROPICAL WAVE AND THE EXTENDED HIGH HUMIDITY
BEHIND IT SUGGEST THAT NEXT WEEK WILL BE SIGNIFICANTLY ABOVE
NORMAL IN TERMS OF RAINFALL FOR THE ENTIRE FORECAST AREA.

&&

.AVIATION...
VFR CONDITIONS WILL PREVAIL ACROSS ALL TAF SITES THROUGH
AT LEAST 24/12Z. HOWEVER...PERIODS OF MVFR CONDITIONS ARE
POSSIBLE OVER TIST...TISX...TNCM AND TKPK IN SHOWERS. AFTER 24/16Z
MVFR TO BRIEF IFR CONDITIONS ARE EXPECTED ACROSS MOST OF THE
TERMINALS DUE TO SHRA/TSRA DEVELOPING ACROSS THE FORECAST
AREA...MTN OBSCURATIONS AND VARIABLE GUSTY WINDS EXPECTED NEAR THE
SHRA/TSRA. SURFACE WINDS WILL CONTINUE MAINLY EAST AT 10 TO 15 KTS.

&&

.MARINE...WINDS AND SEAS ARE BEGINNING TO SUBSIDE SLIGHTLY AND
SMALL CRAFT ADVISORIES COME DOWN AT 6 AM AST FOR ALL BUT THE OUTER
ATLANTIC WATERS. SEAS REMAIN AT OR BELOW 6 FEET FOR MUCH OF NEXT WEEK.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  86  76  86  76 /  70  70  70  70
STT  85  76  86  77 /  60  70  70  70

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...FLASH FLOOD WATCH TO BE ISSUED AROUND 6 AM AST FOR PUERTO
RICO THROUGH SATURDAY AFTERNOON.

VI...NONE.

COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 6 AM AST EARLY THIS
MORNING FOR ANEGADA PASSAGE SOUTHWARD TO 17N- CARIBBEAN WATERS OF
PUERTO RICO FROM 10 NM TO 17N-COASTAL WATERS OF SOUTHERN USVI
VIEQUES AND EASTERN PUERTO RICO OUT 10 NM.

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

&&

$$

13/12