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612
FXCA62 TJSJ 241904
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
304 PM AST THU APR 24 2014

.SYNOPSIS...AT UPPER LEVELS...HIGH PRESSURE WILL BEGIN TO ERODE
WITH THE PASSAGE OF TWO WEAK TROUGHS FRIDAY AFTERNOON AND SUNDAY
NIGHT. THE SUB TROPICAL JET WILL MOVE SOUTH OF THE AREA ON
WEDNESDAY BEFORE THE THIRD TROUGH PASSAGE THE FOLLOWING THURSDAY.

AT MID LEVELS...HIGH PRESSURE WILL GRADUAL SHIFT SOUTHWARD WITH
THE PASSAGE OF A TROUGH ON SUNDAY AND ANOTHER ON THURSDAY. MODEST
MID-LEVEL MOISTURE WILL BEGIN TO BE SEEN ON FRIDAY AND LAST UNTIL
THE FOLLOWING FRIDAY.

AT LOWER LEVELS...WEAK HIGH PRESSURE OVER COASTAL NORTH CAROLINA
WILL SLIDE SOUTHEAST INTO THE WESTERN ATLANTIC...PASSING NORTH OF
PUERTO RICO EARLY SATURDAY MORNING. ANOTHER WEAK FRONT WILL
APPROACH THE AREA EARLY NEXT WEEK FOLLOWED BY HIGH PRESSURE FROM
EASTERN CANADA THAT SINKS SOUTH OVER THE WESTERN ATLANTIC. THIS
PROGRESSION WILL CAUSE EAST SOUTHEASTERLY TRADE WINDS TO
STRENGTHEN OVER THE NEXT 7 TO 10 DAYS. MOISTURE WILL DIMINISH
TONIGHT THROUGH FRIDAY NIGHT AND THEN INCREASE AGAIN THROUGH LATE MONDAY.

&&

.DISCUSSION...A FEW SHOWERS DEVELOPED OVER PUERTO RICO DURING THE
AFTERNOON STRETCHING FROM HORMIGUEROS AND MAYAGUEZ TO MOROVIS AND
OROCOVIS. SHOWERS ARE LIKELY TO CONTINUE THROUGH SUNSET AS
MOISTURE INCREASES OVER THE AREA. SIMILAR SHOWER ACTIVITY IS ALSO
EXPECTED ON FRIDAY. THE GFS HAS NOT BEEN PARTICULARLY CONSISTENT
WITH THE MOISTURE LEVELS DURING THE NEXT 7 TO 10 DAYS AND
OSCILLATES BETWEEN THE BEST MOISTURE BEING TODAY AND THE BEST
BEING MONDAY. NEITHER SCENARIO PROMISES MUCH WITH REGARDS TO
RAINFALL ALTHOUGH A FEW VIGOROUS SHOWERS ARE LIKELY TO DEVELOP
ACROSS WESTERN PUERTO RICO EACH AFTERNOON THROUGH TUESDAY. UPPER
LEVELS WILL ADD SOME ENHANCEMENT ESPECIALLY ON MONDAY...BUT CAPPING WILL
OCCUR AT LEAST THROUGH THE WEEKEND AND HEAVY SHOWERS WILL FIND IT
DIFFICULT TO PROSPER. ALSO GRADUAL COOLING IS EXPECTED DURING THE
NEXT 7 DAYS AS SOUTHEASTERLY FLOW BECOMES MORE EASTERLY...AND
INCREASES...AND THE JET IN THE UPPER ATMOSPHERE SHIFTS SOUTH OF
THE AREA PROMOTING THE INFLUENCE OF COOLER AIR TO THE
NORTH...EVEN IF NO FRONTAL PASSAGE IS POSSIBLE.

&&

.AVIATION...MOSTLY VFR CONDITIONS ARE EXPECTED ACROSS THE LOCAL
FLYING AREA FOR THE NEXT 24 HOURS. LATEST TJSJ SOUNDING INDICATED A
LIGHT AND VARIABLE WIND FLOW ALL THE WAY FROM THE SURFACE TO 15K
FEET...BECOMING FROM THE WEST AND STRONGER ABOVE 15K FEET. VCSH
POSSIBLE ACROSS THE LEEWARD ISLANDS AND EASTERN PUERTO RICO
TERMINALS OVERNIGHT.

&&

.MARINE...SEAS WILL REMAIN RELATIVELY PLACID THROUGH EARLY FRIDAY
AFTERNOON WITH ONLY LIGHT TO MODERATE TRADE WINDS. A NORTHERLY
SWELL IS EXPECTED FROM THE STRONG HIGH PRESSURE TO THE NORTH
BEGINNING LATE FRIDAY AFTERNOON THROUGH FRIDAY NIGHT. SWELLS OF 5
TO 6 FEET WITH PERIODS UP TO 12 SECONDS ARE EXPECTED. SEAS SHOULD
BEGIN TO SUBSIDE AGAIN EARLY SUNDAY MORNING.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  78  89  78  90 /  10  20  10  10
STT  78  85  78  85 /  20  20  20  20

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...NONE.
VI...NONE.
COASTAL WATERS...NONE.
&&

$$

72/12






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