Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 011828
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
228 PM AST MON SEP 1 2014

.SYNOPSIS...MID-UPPER RIDGE WILL DOMINATE THE EASTERN CARIBBEAN
REGION THROUGH THURSDAY. A SERIES OF TROPICAL WAVES WILL MOVE
ACROSS THE ISLANDS THIS WEEK. THE FIRST WAVE REACHES THE LOCAL
ISLANDS LATE TUESDAY AND THE SECOND WAVE IS FORECAST TO CROSS THE
REGION LATE THURSDAY AND FRIDAY. CLOUD AND SHOWER ACTIVITY WILL
INCREASE WITH BOTH WAVES...HOWEVER THE SECOND WAVE IS BETTER
DEFINED/ORGANIZED.

&&

.DISCUSSION...TRADE WINDS HAVE TRANSPORTED PATCHES OF LOW LEVEL
MOISTURE ACROSS THE COASTAL WATERS...U.S. VIRGIN ISLANDS...VIEQUES...
CULEBRA AND THE EASTERN THIRD OF PUERTO RICO EARLY TODAY. LOW LEVEL
WINDS SHIFTED TO THE SOUTHEAST THIS AFTERNOON ALLOWING CU LINES TO
FORM DOWNWIND OF THE USVI...CULEBRA AND VIEQUES. SOME OF THESE CU
LINES/STREAMERS HAVE MOVED OVER EASTERN PR PRODUCING BRIEF PERIODS
OF MODERATE TO LOCALLY HEAVY RAINFALL OVER EL YUNQUE AND PORTIONS
OF THE SAN JUAN METRO AREA. IN ADDITION...SEA BREEZE CONVERGENCE
OVER WESTERN PR HAVE RESULTED IN THE TYPICAL AFTERNOON CONVECTION.

SATELLITE LOOPS SUGGEST A DRY SLOT UPSTREAM OF THE USVI/PR AHEAD
OF THE TROPICAL WAVE. THIS WILL RESULT IN LIMITED SHOWER ACTIVITY
TONIGHT AND OVERNIGHT. MOISTURE AND INSTABILITY ASSOCIATED WITH
THE NEXT TROPICAL WAVE NOW LOCATED OVER THE LESSER ANTILLES WILL
ARRIVE TO THE FORECAST AREA EARLY TUESDAY MORNING. THEREFORE...CLOUD
AND SHOWER COVERAGE WILL INCREASE AS THE WAVE MOVES THROUGH THE
ISLANDS. HOWEVER...NO SIGNIFICANT ACCUMULATIONS ARE EXPECTED WITH
THIS WAVE DUE TO THE PRESENCE OF THE AFOREMENTIONED MID-UPPER
RIDGE ALOFT. DRIER AIR MASS IS EXPECTED ON WEDNESDAY IN THE WAKE
OF THE WAVE. THINGS WILL CHANGE AGAIN LATE THURSDAY THROUGH
FRIDAY WHEN THE SECOND WAVE APPROACHES FROM THE EAST. 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.

&&

.AVIATION...SHRA/TSRA THIS AFT MAINLY NR TJMZ/TJBQ/TJSJ BUT
STREAMING SHRA MAY BARELY BYPASS TJSJ TOWARD SW. AREAS OBSCD MTNS.
SHRA/TSRA CURRENTLY BEGINNING TO ARRIVE AT TNCM/TKPK WL CONT INTO
NITE. OTW VFR ALL TAF SITES XCP BRF MVFR IN ISOLD/SCT SHRA. WND BLO
FL200 E-ESE INCR 13-22 KT TONITE/TUE.

&&

.MARINE...SEAS OF 3 TO 4 FEET AND WINDS OF 13-18 KT CAN BE EXPECTED
OVER THE NEXT SEVERAL DAYS. SMALL CRAFT ADVISORIES ARE NOT EXPECTED
THROUGH AT LEAST THE END OF THE WEEK.

&&

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

&&

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

$$

54/11





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