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714 FXCA62 TJSJ 030250 AAA AFDSJU AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE SAN JUAN PR 1050 PM AST WED OCT 2 2013 .UPDATE...SOUNDING CAME IN AT 2.02 INCHES THIS EVENING WHICH IS SIMILAR TO THE SOUNDING FROM 24 HOURS AGO. SOUNDER DATA WAS NOT AVAILABLE DUE TO GOVERNMENT SHUT DOWN. MODELS ARE INCONCLUSIVE AS TO THE TREND IN MOISTURE CONTENT AND EXPECT NO SIGNIFICANT CHANGES DURING THE NEXT 24 HOURS. WRF DID SEE THE PEAK PRECIPITABLE WATER OVER 2 INCHES TODAY BUT DOES NOT SEE THE PEAK OVER 2 INCHES THURSDAY AS THE GFS DOES. WIND DIRECTION WILL BE A PRIMARY PLAYER THURSDAY AS A SHIFT BACK TO EAST SOUTHEAST FLOW MOVES THE PRIMARY FOCUS BACK TO CENTER OF WESTERN PUERTO RICO AND THEN TO THE NORTHWEST FRIDAY. SHOWERS AND THUNDERSTORMS WILL CONTINUE IN ABOUT THE SAME COVERAGE THURSDAY AND THEN INCREASE FRIDAY. && .DISCUSSION...SHOWERS AND THUNDERSTORMS CONTINUED OVER WATER IN BOTH THE ATLANTIC AND CARIBBEAN...AND A FEW SHOWERS WERE SEEN IN THE NORTHEAST QUARTER OF MAINLAND PUERTO RICO. WOULD EXPECT THIS TREND TO CONTINUE. && .AVIATION...VFR CONDITIONS ARE EXPECTED TO CONTINUE THROUGH AT LEAST 03/17Z. AFTERNOON CONVECTION OVER THE INTERIOR AND WESTERN PR COULD PRODUCE TEMPO MVFR OR EVEN IFR CONDS AT TJMZ BTWN 03/17-21Z. VCSH/VCTS ARE LIKELY NEAR TJBQ...TJPS AND POSSIBLY TJSJ WITH THE AFTERNOON SHRA/TSRA. MOUNTAIN OBSCURATIONS ARE ALSO LIKELY ACROSS WESTERN INTERIOR PR. THROUGH THE FORECAST PERIOD...LLVL WIND WILL BE MAINLY FM THE EAST AT 10-15 KT BLO FL150. LIGHT AND VARIABLE WINDS ARE EXPECTED ABV 20 KFT AFT 03/06Z. && .MARINE...SEAS ARE INCREASING SLIGHTLY AND NOW RANGE 4 TO 5 FEET IN OFFSHORE WATERS AND 3 TO 4 FEET IN THE NEAR SHORE WATERS. NO CHANGE TO PREVIOUS DISCUSSION. && .PREV DISCUSSION... /ISSUED 249 PM AST WED OCT 2 2013/ SYNOPSIS...RIDGE ALOFT WILL CONTINUE TO ERODE TONIGHT...AS UPPER LEVEL TROUGH AMPLIFIES ACROSS THE WESTERN ATLANTIC. UPPER LOW ASSOCIATED WITH AFOREMENTIONED TROUGH WILL PREVAIL NORTH OF THE AREA THROUGH FRIDAY. A SECOND UPPER LEVEL LOW WILL THEN DEVELOP NORTHWEST OF LOCAL ISLANDS EARLY NEXT WEEK AND REMAIN NEARLY STATIONARY THROUGH MID NEXT WEEK. DISCUSSION...VARIABLY TO PARTLY CLOUDY SKIES PREVAILED ACROSS THE LOCAL ISLANDS TODAY. SHOWERS WITH THUNDERSTORMS AND LOCALLY HEAVY RAINFALL WERE NOTED ACROSS PORTIONS OF THE CORDILLERA CENTRAL AS WELL AS WEST PUERTO RICO IN THE AFTERNOON. WINDS WERE EASTERLY AT 10 TO 15 MPH WITH COASTAL TEMPERATURES IN THE LOW 90S. THE LOCAL ISLANDS WILL BECOME UNDER THE INFLUENCE OF A MID TO UPPER LEVEL TROUGH WHICH WILL INTERACT WITH PATCHES OF LOW LEVEL MOISTURE AND LOCAL EFFECTS TO PRODUCE CLOUDINESS AND SHOWERS WITH THUNDERSTORMS ACROSS PORTIONS OF THE LOCAL ISLANDS. IN FACT...MODEL GUIDANCE SUGGESTED A SHARP INCREASE IN PRECIPITABLE WATER OVER THE NEXT FEW DAYS WITH VALUES PEAKING NEAR 2.2 INCHES FRIDAY NIGHT-SATURDAY MORNING. AS A RESULT THURSDAY THROUGH THE EARLY PART OF THE UPCOMING WEEKEND... UNDER A MOIST/UNSTABLE AIR MASS AND THE PREVAILING WIND FLOW... EXPECT THE CONTINUED TREND OF PASSING SHOWERS ACROSS USVI AND EASTERN PUERTO RICO DURING THE MORNING HOURS...FOLLOWED BY AFTERNOON CONVECTION WHICH WILL BE FOCUSED BUT NOT LIMITED TO WESTERN PUERTO RICO. SUNDAY INTO EARLY NEXT WEEK...MOIST AND UNSTABLE CONDITIONS WILL CONTINUE TO PREVAIL ACROSS THE FORECAST AREA AS A SECOND UPPER LEVEL LOW DEVELOPS NORTHWEST OF THE LOCAL AREA AND A BROAD SURFACE TROUGH DOMINATES THE CENTRAL AND WESTERN CARIBBEAN. AVIATION...VFR CONDITIONS WITH BRIEF MVFR IN ISOLD/SCT SHRA/TSRA THIS AFTERNOON UNTIL 02/23Z ACROSS WEST INTERIOR PR TO WESTERN SHORE...CAUSING OBSCURED MTNS AND MVFR TO ISOLD IFR. WIND UP TO 2 KFT NE 5-15 KT THRU TONIGHT THEN ENE THU. MARINE...SEAS 3 TO 5 FEET EXPECTED THROUGH TOMORROW IN MIXED NNE SWELLS AND ENE WIND WAVES...DIMINISHING TO 2 TO 3 FEET FRIDAY INTO THE WEEKEND. && .PRELIMINARY POINT TEMPS/POPS... SJU 77 88 81 88 / 40 40 50 50 STT 82 88 82 89 / 50 50 50 50 && .SJU WATCHES/WARNINGS/ADVISORIES... PR...NONE. VI...NONE. COASTAL WATERS...NONE. && $$ 11/12
