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000
FXCA62 TJSJ 201452
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1052 AM AST MON MAY 20 2013

.UPDATE...AFTERNOON CONVECTION TODAY MIGHT BE A SHADE MORE THAN
EXPECTED AND BOOSTED PROBABILITIES A LITTLE...BUT NOT EXPECTING
FLOODING ISSUES ATTM.

&&

.DISCUSSION...PRECIPITABLE WATER ON 12Z TJSJ SOUNDING WAS 1.89
INCHES AND GFS KEEPS OVERESTIMATING THE DRY ADVECTION FROM THE
EAST. MOISTURE IS SUFFICIENT FOR ANOTHER ROUND OF SHOWERS/THUNDER
OVER WESTERN PR SIMILAR OR PERHAPS SLIGHTLY MORE THAN OCCURRED ON
SUNDAY. ALMOST FULL SUNSHINE STILL OVER THE WESTERN INTERIOR
ENSURES ENOUGH INSTABILITY TO GET CONVECTION GOING.

&&

.AVIATION...CONT VFR BUT MAY NEED A TEMPO GROUP IN TJMZ TAF IF
CONVECTION INCR QUICKLY. A FEW OBSC MTNS XPCTD ACROSS WESTERN
CORDILLERA. LLVL WIND E 10-20 KT BLO FL100 BCMG W INCR SPD ABV.

&&

.MARINE...LITTLE CHANGE THRU TUE. SEAS GENERALLY UNDER 6 FT AND
WINDS UNDER 18 KT. CAUTION FOR SMALL CRAFT.

&&

.PREV DISCUSSION... /ISSUED 549 AM AST MON MAY 20 2013/

SYNOPSIS...SURFACE HIGH PRESSURE IS EXPECTED TO STRENGTHENS NORTH
NORTHEAST OF THE LOCAL AREA FOR THE NEXT SEVERAL DAYS. LOW LEVEL
PERTURBATIONS IN THE EASTERLY TRADES WILL MOVE OCCASIONALLY ACROSS
THE LOCAL ISLANDS FOR THE NEXT SEVERAL DAYS.

DISCUSSION...LATEST SATELLITE IMAGES AND TERMINAL DOPPLER RADAR
OBSERVATIONS OVERNIGHT AND EARLY THIS MORNING...DEPICTED SCATTERED
SHOWERS AND A FEW THUNDERSTORMS MOVING WESTWARD MAINLY ACROSS THE
ATLANTIC COASTAL WATERS. THE STRENGTHENING SURFACE HIGH
PRESSURE...JUST NORTH OF THE AREA THIS MORNING...WILL MAINTAIN AN
EASTERLY TRADE WIND FLOW ACROSS THE REGION FOR THE REST OF THE WORK
WEEK. THIS FEATURE WILL ALSO TIGHTENS THE LOCAL PRESSURE
GRADIENT...INCREASING THE WINDS FLOW ACROSS THE REGION. AS THIS
HAPPENS...SOME LOW LEVEL PERTURBATIONS WILL CROSS THE REGION
OCCASIONALLY PRODUCING INTERMITTENT PERIODS OF CLOUDINESS AND
SHOWERS ACROSS THE LOCAL ISLANDS. PWAT VALUES WILL PREVAIL CLOSE TO
1.60 INCHES TODAY AND TUESDAY...BUT WILL INCREASE STEADILY TO AROUND
2.00 INCHES LATE WEDNESDAY AND THURSDAY AS A SURGE OF MOISTURE
ASSOCIATED WITH A LOW LEVEL PERTURBATION APPROACHES TO THE REGION
FROM THE EAST. A WEAK EASTERLY WAVE...EMERGING TO THE AFRICAN COASTS
TODAY...IS EXPECTED TO REACH THE REGION BY THE UPCOMING WEEKEND OR
EARLY NEXT WEEK. COMPUTER MODELS GUIDANCE ARE CONSISTENT IN A WET
PERIOD STARTING SATURDAY AND CONTINUING THROUGHOUT THE EARLY PART OF
THE UPCOMING WEEK. STAY TUNED.

AVIATION...VFR CONDITIONS ARE EXPECTED TO PREVAIL AT ALL TAF
SITES FOR THE NEXT 24 HRS. HOWEVER...AFT 20/16Z SHOWERS AND A
FEW THUNDERSTORMS ARE EXPECTED TO DEVELOP ONCE AGAIN OVER THE
CORDILLERA CENTRAL AND MAY CAUSE TEMPO MVFR CONDS AT TJMZ BTW
20/16Z AND 20/22Z. EASTERLY WINDS AT 10 KNOTS OR LESS EXPECTED
OVERNIGHT.

MARINE...SEAS OF 5 FEET OR LESS AND WINDS OF OF 20 KNOTS OR LESS.
SMALL CRAFT ARE URGED TO EXERCISE CAUTIONS ACROSS ALL OF THE LOCAL
COASTAL WATERS.

PRELIMINARY POINT TEMPS/POPS...
SJU 86 77 86 76 / 20 20 40 30
STT 87 77 87 78 / 20 30 30 30

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  86  77  86  76 /  20  20  40  30
STT  87  77  87  78 /  20  30  30  30

&&

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

$$

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