Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 030247
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1047 PM AST TUE SEP 2 2014

.UPDATE...ONLY LIGHT PASSING SHOWERS WERE NOTED TONIGHT OVER THE
LOCAL COASTAL WATERS...WITH VERY LITTLE ACTIVITY OVER LAND AREAS.
A SLOT OF DRIER AIR HAS MOVED ACROSS THE AREA TONIGHT...WHICH WILL
LIMIT THE SHOWER ACTIVITY ACROSS THE AREA. NO CHANGES NEEDED TO
FORECAST GRIDS TONIGHT.

&&

.AVIATION...VFR TONITE/WED MRNG XCP VERY OUTSIDE CHC MVFR IN ISOLD
SHRA. WND OVERNIGHT RANGE FROM LGHT AND VARIABLE TO MAINLY EAST AT 5
TO 10 KTS...BCMNG EAST AT 10 TO 16 KTS WITH HIGHER GUSTS LTR WED
MRNG. TYPICAL AFT SHRA POSSIBLE WITH CHANCE OF TSRA FOR TJMZ AND
VCTS FOR TJBQ TIL AROUND 03/21Z.

&&

.MARINE...NO CHANGES TO PREVIOUS DISCUSSION.

&&

.PREV DISCUSSION... /ISSUED 321 PM AST TUE SEP 2 2014/

SYNOPSIS...RIDGE ALOFT WILL DOMINATE THE EASTERN CARIBBEAN REGION
THROUGH THURSDAY. THEN...UPPER RIDGE MIGRATES WEST ALLOWING A TUTT TO
RELOCATES NORTH OF THE LOCAL ISLANDS EARLY FRIDAY. A SERIES OF
TROPICAL WAVES WILL CROSS THE FORECAST AREA THIS WEEK. THE FIRST
WAVE IS CROSSING PR TODAY...THE SECOND WAVE IS FORECAST TO MOVE
ACROSS THE REGION LATE THURSDAY AND FRIDAY AND THE NEXT WAVE WILL
BE ON SUNDAY. SURFACE HIGH PRESSURE NORTH OF THE ISLANDS WILL
CONTINUE TO PUSH TRADE WINDS SHOWERS ACROSS THE LOCAL AREA FROM
TIME TO TIME.

DISCUSSION...SATELLITE IMAGERY AND SURFACE ANALYSIS SHOWED THE AXIS
OF THE TROPICAL WAVE OVER THE ISLANDS EARLY THIS AFTERNOON. THIS
WAVE HAVE PRODUCED SHOWERS OVER NORTHWEST PR AND STREAMERS DOWNWIND
OF EL YUNQUE AND THE SMALL ISLANDS. POCKETS OF HEAVY RAINFALL HAVE
BEEN OBSERVED IN CATANO...NORTHERN BAYAMON...TOA BAJA AS WELL AS
AGUADILLA AND VICINITY. NEW SHOWERS ARE ALSO POSSIBLE ACROSS THESE
AREA AS WELL AS THE NORTH...WEST AND INTERIOR SECTIONS OF PUERTO RICO
LATER THIS AFTERNOON.

SATELLITE LOOPS SUGGEST DRIER AIR MASS UPSTREAM OF THE USVI/PR
BEHIND OF THE WAVE. INSTABILITY AND MOISTURE ASSOCIATED WITH THIS
WAVE WILL MOVE INTO MONA PASSAGE/HISPANOLA TONIGHT...LEAVING THE
LOCAL ISLANDS WITH MAINLY PARTLY CLOUDY SKIES AND ISOLATED/SCATTERED
SHOWERS TONIGHT AND OVERNIGHT HOURS.

MOISTURE AND INSTABILITY WILL INCREASE ONCE AGAIN ON THURSDAY WHEN
THE NEXT TROPICAL WAVE MOVES OVER THE NORTHEAST CARIBBEAN ISLES. AT
THIS TIME...IT APPEARS THAT THIS WAVE WILL BRING ORGANIZED CONVECTION
AND BETTER RAINFALL AMOUNTS TO THE ISLANDS...ESPECIALLY ON FRIDAY
WHEN THE AXIS OF THE WAVE PASSES AND THE WINDS VEER TO THE SOUTHEAST.
IN ADDITION...THE PROXIMITY OF AN UPPER LEVEL TROUGH NORTH OF THE
ISLANDS WILL ENHANCE THE CONVECTION ASSOCIATED WITH THE WAVE...
RESULTING IN PERIODS OF INTENSE RAINFALL. THEN... ANOTHER WAVE
WILL REACH THE ISLANDS ON SUNDAY. OVERALL...EXPECT A RELATIVELY
WET PATTERN THE REST OF THE WEEK...EXPECT WEDNESDAY AND SATURDAY.

AVIATION...PD SHRA/TSRA W-N PR THIS AFT INCLUDING TJMZ/TJBQ/TJSJ...
SOME OBSCD MTNS. THEN VFR TONITE/WED MRNG XCP VERY OUTSIDE CHC MVFR
IN ISOLD SHRA. WND SFC-FL200 ESE-SE 14-23 KT BCMG E THIS EVE AND
CONT THRU WED. SHRA INCR TNCM/TKPK WED EVE.

MARINE...CONDITIONS WILL CONTINUE FAVORABLE WITH WINDS OF 13-18
KT AND SEAS OF 3-5 FT THEN IMPROVE FURTHER LATE IN THE WEEK.
THUNDERSTORMS ALSO CREATE HAZARDS...WHICH WILL OCCUR PERIODICALLY.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  78  90  79  88 /  30  40  50  50
STT  79  90  80  89 /  30  30  50  50

&&

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

$$

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