Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 281858
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
258 PM AST FRI AUG 28 2015

.SYNOPSIS...AT UPPER LEVELS...WEAK GRADIENTS AND GENERALLY HIGH
PRESSURE WILL PERSIST THROUGH MONDAY. A TROUGH WILL FORM NORTH OF
THE AREA MONDAY AND SLOWLY DRIFT SOUTH ACROSS THE AREA BY
WEDNESDAY. ANOTHER TROUGH WILL DIG DOWN FROM THE NORTH NORTHEAST
BY FRIDAY.

AT MID LEVELS...HIGH PRESSURE WILL PERSIST NORTH AND NORTHWEST OF
THE LOCAL AREA. MID LEVELS WILL DRY AS ERIKA MOVES FARTHER
AWAY...THEN A WEAK TROUGH WILL BRING MOISTURE FOR SUNDAY. A SECOND
TROUGH WILL MOVE THROUGH WEDNESDAY INTO THURSDAY.

AT LOWER LEVELS...TROPICAL STORM ERIKA IS NOW SOUTH OF HISPANIOLA
AND THE STRONGEST CONVECTION IN ITS SOUTHEAST QUADRANT IS
SOUTHWEST OF THE FORECAST AREA. DRIER AIR IS MOVING IN BEHIND IT.
TWO TROUGHS WILL BRING SHOWERS AND ISOLATED THUNDERSTORMS SUNDAY
AND WEDNESDAY AND THURSDAY.

&&

.DISCUSSION...SCATTERED SHOWERS FORMED IN ONE OF THE LAST RAIN
BANDS FROM TROPICAL STORM ERICA AND ARE BRINGING BETWEEN 1 AND 2
INCHES OF RAINFALL TO WESTERN PUERTO RICO AS THEY TRAVERSE THE
WEST CENTRAL PORTION OF THE ISLAND FROM SOUTH SOUTHEAST TO NORTH
NORTHWEST. SOME OF THEM HAD GUSTY WINDS FROM THE WIND FLOW ONLY
HUNDREDS OF FEET ABOVE. A SPECIAL MARINE WARNING WAS ISSUED FOR
THE COASTAL WATERS THAT THESE STORMS ENTERED BY MID AFTERNOON. ISOLATED
SHOWERS ARE FORMING IN NORTHEAST PUERTO RICO WITH LIMITED
ACCUMULATIONS.

CONTINUED DRYING IS EXPECTED OVERNIGHT AS MID LEVEL MOISTURE
LEAVES THE AREA. THIS WILL NOT PROHIBIT SCATTERED SHOWERS AND
THUNDERSTORMS FROM FORMING SATURDAY AFTER NOON. ALTHOUGH THE BULK
OF THIS SHOULD BE IN NORTHWEST PUERTO RICO SOME MAY FORM AS A
RESULT OF CONVERGENCE OVER THE HILLS IN NORTHEAST PUERTO RICO. A
WEAK TROUGH WILL MOVE THROUGH ON SUNDAY WITH AN INCREASE IN
SHOWERS AND THUNDERSTORMS SUNDAY AFTERNOON. A SECOND TROUGH WILL
BRING A LITTLE MORE MOISTURE ON WEDNESDAY AND THURSDAY FOR
ADDITIONAL SHOWERS. AFTERNOON SHOWERS AND THUNDERSTORMS WILL
NEVERTHELESS OCCUR IN WESTERN PUERTO RICO EACH DAY NEXT WEEK. THE
TWO WAVES DO NOT APPEAR TO HAVE ANY PROPENSITY FOR DEVELOPMENT
INTO TROPICAL STORMS AT THIS TIME...BUT MODELS SHOW A CIRCULATION
DEVELOPING IMMEDIATELY UPON EXIT OF A WAVE OFF THE AFRICAN COAST
ON SUNDAY. THIS CIRCULATION WOULD NOT REACH PUERTO RICO IN THE
CURRENT SYNOPTIC PATTERN.

&&

.AVIATION...CLOUDY SKIES WITH PATCHES OF LIGHT TO MODERATE RAIN
ASSOCIATED WITH THE TRAILING MOISTURE ASSOCIATED WITH TROPICAL
STORM ERIKA WILL CONTINUE TO AFFECT TJPS...TJMZ AND TJBQ THIS
EVENING WITH CIGS NEAR FL050. VCSH EXPECTED ELSEWHERE OVER THE
LOCAL FLYING AREA. HOWEVER CONDITIONS WILL GRADUALLY IMPROVE AFTER
29/02Z...BUT VCSH/VCTS ARE POSSIBLE. LATEST UPPER AIR TJSJ
SOUNDING INDICATED 30-55 KT SSE WINDS BETWEEN 1000-9000 FT.

&&

.MARINE...SEAS ARE STILL RUNNING ABOVE 7 FEET ALONG THE WESTERN
SOUTH COAST OF PUERTO RICO AND MOST OF THE OUTER ATLANTIC WATERS
AS THE EFFECTS OF ERIKA SLOWLY SUBSIDE. WATERS NEAR RINCON AND ALL
AROUND THE U.S. VIRGIN ISLANDS AND NEAR-SHORE ALONG THE EASTERN
PORTION OF THE NORTH COST OF PUERTO RICO ARE GENERALLY NEAR OR
BELOW 4 FEET AND WILL CONTINUE TO SUBSIDE TONIGHT.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  77  90  80  90 /  20  20  40  40
STT  77  90  80  90 /  30  30  40  40

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...HIGH RIP CURRENT RISK UNTIL 6 PM AST THIS EVENING FOR CENTRAL
     INTERIOR-CULEBRA-MAYAGUEZ AND VICINITY-NORTH CENTRAL-
     NORTHEAST-NORTHWEST-PONCE AND VICINITY-SAN JUAN AND
     VICINITY-SOUTHEAST-SOUTHWEST-VIEQUES-WESTERN INTERIOR.

     SMALL CRAFT ADVISORY FROM 6 PM TO 11 PM AST THIS EVENING FOR
     SOUTHEAST.

VI...HIGH RIP CURRENT RISK UNTIL 6 PM AST THIS EVENING FOR ST CROIX-
     ST. THOMAS/ST. JOHN/ADJACENT ISLANDS.

AM...HIGH RIP CURRENT RISK UNTIL 6 PM AST THIS EVENING FOR COASTAL
     WATERS OF NORTHERN USVI AND CULEBRA OUT 10 NM-COASTAL
     WATERS OF SOUTHERN PUERTO RICO OUT 10 NM-COASTAL WATERS OF
     SOUTHERN USVI VIEQUES AND EASTERN PUERTO RICO OUT 10 NM-
     COASTAL WATERS OF SOUTHWESTERN PUERTO RICO OUT 10 NM.

     SMALL CRAFT ADVISORY UNTIL 11 PM AST THIS EVENING FOR CARIBBEAN
     WATERS OF PUERTO RICO FROM 10 NM TO 17N-COASTAL WATERS OF
     NORTHERN PUERTO RICO OUT 10 NM-COASTAL WATERS OF SOUTHERN
     PUERTO RICO OUT 10 NM-MONA PASSAGE SOUTHWARD TO 17N.

     SMALL CRAFT ADVISORY UNTIL 5 AM AST SATURDAY FOR ATLC WATERS OF
     PUERTO RICO AND USVI FROM 10NM TO 19.5N.

     SMALL CRAFT ADVISORY UNTIL 6 PM AST THIS EVENING FOR COASTAL
     WATERS OF NORTHWESTERN PUERTO RICO OUT 10 NM-COASTAL WATERS
     OF SOUTHWESTERN PUERTO RICO OUT 10 NM.

&&

$$

11/12


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