Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 041904
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
304 PM AST MON MAY 4 2015

.SYNOPSIS...AT MID AND UPPER LEVELS...HIGH PRESSURE IN THE
EASTERN TROPICAL ATLANTIC WILL WEAKEN VERY SLOWLY. A TROUGH
DIGGING INTO THE NORTHWESTERN CARIBBEAN WILL REACH HISPANIOLA BY
MONDAY OF NEXT WEEK AND THEN WEAKEN AS IT PASSES NORTH OF THE AREA
MONDAY NIGHT. MID LEVELS REMAIN DRY THROUGH THE END OF THE WEEK.

AT LOWER LEVELS...HIGH PRESSURE IN THE WESTERN ATLANTIC EAST OF
THE MID ATLANTIC UNITED STATES WILL DRIFT EAST SOUTHEAST TO THE
CENTRAL ATLANTIC AND WEAKEN CONSIDERABLY BY THE END OF THE WEEK. A
LOW PRESSURE BUILDS NORTH OF CUBA TUESDAY AND MOVES NORTH INTO
SOUTH CAROLINA BY FRIDAY...CAUSING LOCAL WINDS TO BECOME SOUTHEAST
AGAIN BY MID WEEK AND CONTINUE THROUGH THE END OF THE WEEK.
SIGNIFICANT RAINFALL IS NOT EXPECTED NOW THROUGH SATURDAY WITH
MINOR AMOUNTS POSSIBLE SUNDAY THROUGH MID WEEK NEXT WEEK.

&&

.DISCUSSION...FEWER SHOWERS WERE DETECTED TODAY...AND THOSE
SHOWERS THAT DID APPEAR LASTED ON THE ORDER OF A FEW MINUTES.
GENERAL DRYING IS EXPECTED TONIGHT THROUGH WEDNESDAY WITH A VERY
MINIMAL INCREASE IN LOW LEVEL MOISTURE THEREAFTER. THE MAJOR
CHANGE IS THAT MID AND UPPER LEVELS WILL BEGIN TO SEE RELATIVE
HUMIDITIES INCREASE AFTER SUNDAY AS THE UPPER LEVEL TROUGH
APPROACHES. THE GFS SHOWS THAT MOISTURE STILL REMAINS WEAK BETWEEN
850 MB AND 650 MB BEYOND THURSDAY OF NEXT WEEK EVEN THOUGH
PRECIPITABLE WATER RISES TO 1.9 INCHES ON SUNDAY AND REMAINS ABOVE
1.5 INCHES THROUGH THE WEEK. THIS WILL LIMIT THE AMOUNT AND EXTENT
OF ANY PRECIPITATION THAT WOULD HAVE FALLEN NEXT WEEK.

&&

.AVIATION...MOSTLY VFR CONDITIONS EXPECTED ACROSS THE LOCAL FLYING
AREA FOR THE NEXT 24 HOURS. ONLY VCNTY SHOWERS ARE POSSIBLE ACROSS
TJBQ AND TJMZ UNTIL AT LEAST 04/22Z. WINDS WILL CONTINUE FROM THE
EAST TO EAST SOUTHEAST UP TO 25 KNOTS ALL THE WAY FROM THE SURFACE
UP TO AROUND 25K FEET.

&&

.MARINE...WINDS AND SEAS WILL INCREASE AS THE SURFACE PRESSURE
GRADIENT RISES WITH THE HIGH PRESSURE PASSING NORTH OF THE AREA.
EXPECT WINDS UP TO 20 KNOTS IN MOST EXPOSED WATERS WITH WINDS A
LITTLE HIGHER AROUND CERTAIN PINCH POINTS FOR THE AIR
FLOW...MAINLY AROUND SOUTHWEST AND NORTHWEST PUERTO RICO. SOME
GUSTS COULD EXCEED 30 KNOTS. SEAS WILL ALSO RISE TO 7 FEET MAINLY
IN THE WESTERN HALF OF THE FORECAST AREA.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  78  89  78  90 /   0   0   0  10
STT  78  87  78  88 /  10  10   0  10

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...NONE.
VI...NONE.
AM...SMALL CRAFT ADVISORY FROM 2 AM TO 8 PM AST TUESDAY FOR ATLC
     WATERS OF PUERTO RICO AND USVI FROM 10NM TO 19.5N.

     SMALL CRAFT ADVISORY FROM 2 AM TUESDAY TO 8 PM AST WEDNESDAY FOR
     CARIBBEAN WATERS OF PUERTO RICO FROM 10 NM TO 17N-MONA
     PASSAGE SOUTHWARD TO 17N.

&&

$$

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