361 
FXCA62 TJSJ 200224 AAA
AFDSJU

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SAN JUAN PR
1024 PM AST SUN MAY 19 2013

.UPDATE...THE 20/00Z SOUNDING CAME IN CLEARLY WETTER IN MANY
LAYERS AND SOMEWHAT WETTER IN PRECIPITABLE WATER OVER THE LAST 24
HOURS. THE GFS 19/18Z RUN SHOWED DRIER AIR MOVING IN OVER THE AREA
TOMORROW AND EXPECT SLIGHTLY LESS ACTIVITY IN THE WESTERN PORTION
OF PUERTO RICO AS PREVIOUSLY FORECAST...BUT ALSO EXPECT THIS TREND TO
REVERSE TUESDAY AND WEDNESDAY. CURRENTLY THE MODEL IS SHOWING THE
WETTEST DAYS TO BE SATURDAY AND SUNDAY. THIS WOULD BE JUST A
LITTLE AHEAD OF THE ESTIMATED ARRIVAL OF THE AFRICAN EASTERLY WAVE
THAT JUST LEFT THE WEST COAST OF AFRICA TODAY. SO PERHAPS THE GFS
WILL DELAY THIS EVENT STILL A LITTLE MORE. OTHERWISE STILL LOOKING
FOR INCREASING ACTIVITY NEXT WEEK. ONE CAVEAT. THE GFS IS SHOWING
WEAK MOISTURE BETWEEN 850 AND 725 MB THROUGH THE NEXT 7 DAYS AND
HAVE TO THINK THAT THIS WILL AFFECT THE AMOUNT OF RAIN THAT FALLS.
250 MB DIVERGENCE APPEARS TO BE COUNTER BALANCED WITH 300-400 MB
CONVERGENCE KEEPING STRONG UPWARD VERTICAL MOTION CONFINED TO
UPPER LAYERS...AND THIS IS IN SYNCH WITH HIGH LEVELS OF UPPER
LEVEL CLOUDINESS. THIS TOO MAY IMPEDE HEAVY RAIN LATER...SO MODELS
ARE SENDING A VERY MIXED MESSAGE ABOUT WETTER WEATHER LATER THIS
WEEK. SOME CHANGES TO THE GRIDS...MAINLY POPS AND WEATHER TO MORE
CLOSELY REFLECT LATEST MODEL GUIDANCE. 

&&

.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 BTWN 20/16Z AND 20/22Z. EASTERLY
WINDS AT 10 KNOTS OR LESS EXPECTED OVERNIGHT.

&&

.MARINE...SEAS BELOW 5 FEET...BUT WINDS HAVE BEGUN TO INCREASE IN
ATLANTIC WATERS. NO CHANGE IN MARINE FORECAST.


&&

.PREV DISCUSSION... /ISSUED 256 PM AST SUN MAY 19 2013/ 

SYNOPSIS...SURFACE HIGH PRESSURE IS EXPECTED TO ESTABLISH NORTH
OF THE LOCAL ISLANDS FOR MOST OF THE WEEK. WEAK UPPER TROUGH TO
THE WEST OF THE LOCAL AREA IS EXPECTED TO MOVE EASTWARD AND OVER
THE LOCAL AREA BY THURSDAY.

DISCUSSION...LIMITED BUT ENOUGH AVAILABLE MOISTURE COMBINED WITH
THE LOCAL EFFECT TO PRODUCE SHOWERS ACROSS THE INTERIOR AND
WESTERN SECTIONS OF PUERTO RICO AS MOISTURE INCREASED SLIGHTLY
THROUGH THE DAY. THIS TREND OF INCREASE IN MOISTURE IS EXPECTED TO
CONTINUE THROUGH THE WEEK. SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS ARE FORECAST FOR THE NEXT FEW DAYS ACROSS THE
WESTERN AND INTERIOR SECTIONS OF PUERTO RICO SINCE THE AVAILABLE
MOISTURE IS EXPECTED TO COMBINE WITH THE LOCAL EFFECTS. FOR
WEDNESDAY ONWARD...A BIT MORE SHOWERY AND UNSETTLED PATTERN IS
INDICATED BY THE GFS MODEL...CAUSING SCATTERED SHOWERS ACROSS A
LARGER PORTION OF THE FORECAST AREA.

AVIATION...DEVELOPING SHRA/TSRA WILL CAUSE MVFR/IFR CONDITIONS
ACROSS IN AND AROUND TJMZ UNTIL 19/22Z. THEREAFTER...SKIES WILL
REMAIN PARTLY CLOUDY TO MOSTLY CLEAR WITH EASTERLY WINDS AT 10
KNOTS OR LESS. AFTER 20/16Z ANOTHER ROUND OF SHRA/TSRA POSSIBLE
THAT SHOULD AFFECT TJMZ AND TJBQ. 

MARINE...SMALL CRAFT SHOULD EXERCISE CAUTION DUE TO WINDS OF UP TO
20 KNOTS. SEAS ARE EXPECTED TO REMAIN AT 5 FEET OR LESS. THIS GENERAL
PATTERN IN MARINE CONDITIONS IS EXPECTED FOR THE NEXT FEW DAYS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  78  87  77  85 /  30  20  20  40 
STT  77  88  78  88 /  20  20  30  30 

&&

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

$$

23/12