915 FXCA62 TJSJ 050339 AFDSJU AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JUAN PR 1139 PM AST THU DEC 4 2008 .UPDATE...MOSTLY CLEAR SKIES HAVE BEEN OBSERVED ACROSS THE FORECAST AREA THIS EVENING. WITH A LARGE AREA OF SURFACE HIGH PRESSURE MOVING ACROSS THE WESTERN ATLANTIC AT THIS TIME...MODERATE TO FRESH EAST NORTHEAST TRADE WINDS HAVE BEEN CONTINUING ACROSS SECTIONS OF THE ISLANDS AND LOCAL COASTAL WATERS ALL DAY. AN AREA OF MOISTURE VISIBLE IN SATELLITE IMAGERY UPSTREAM OF THE AREA TONIGHT...SHOULD BRING SCATTERED SHOWERS TO THE NORTH COAST OF PUERTO RICO...AND POSSIBLY SECTIONS OF THE VI...TOWARDS EARLY MORNING FRIDAY...WITH LITTLE SHOWER ACTIVITY EXPECTED ELSEWHERE. ADDITIONAL AREAS OF VERY SHALLOW PATCHY MOISTURE WILL CONTINUE TO BRING PERIODS OF SHOWERS ACROSS THE LOCAL AREA FROM TIME TO TIME THROUGH THE UPCOMING WEEKEND...BUT WITH STRONG HIGH PRESSURE PERSISTING IN THE MID TO UPPER LEVELS OF THE ATMOSPHERE...THIS SHOWER ACTIVITY SHOULD BE SHORT LIVED AND RELATIVELY ISOLATED. OVERALL...ONLY A FEW MINOR TWEAKS MADE TO INHERITED FORECAST THIS EVENING AS PREVIOUS FORECAST REMAINS IN LINE WITH CURRENT THINKING. && .AVIATION...AN AREA OF SHALLOW MOISTURE WITH EMBEDDED SHOWERS IN THE LOW LEVEL NORTHEAST FLOW WILL CONTINUE ACROSS THE U.S. VIRGIN ISLANDS AND PUERTO RICO THROUGH 10Z...PRODUCING BRIEF PERIODS OF MVFR ACROSS TISX...TIST AND TJSJ. AFTER 10Z...MOSTLY VFR CONDITIONS WILL PREVAIL ACROSS THE LOCAL AIRPORTS...HOWEVER BRIEF MVFR CONDITIONS WILL BE POSSIBLE THROUGH THE EARLY MORNING HOURS IN SOME AREAS. LATEST INFORMATION FROM THE MONTSERRAT VOLCANO OBSERVATORY AS WELL AS SATELLITE IMAGERY INDICATED A FAINT ASH PLUME EXTENDING SOUTHWEST FROM THE ISLAND. THE CURRENT AND FORECAST WIND FLOW WILL MAINTAIN THE ASH PLUME AND GAS EMISSIONS WELL SOUTH OF THE LOCAL FLYING AREA. NO OTHER OPERATIONAL FLYING HAZARD ARE FORECAST AT THIS TIME. PLEASE REFER TO LATEST VAAC (WASHINGTON) ADVISORIES FOR UPDATES. && .PREV DISCUSSION... /ISSUED 410 PM AST THU DEC 4 2008/ DISCUSSION...ELONGATED MID TO UPPER LEVEL RIDGE WILL BE THE DOMINANT WEATHER FEATURE LOCALLY FOR THE NEXT SEVERAL DAYS... KEEPING A CAP ON MOST DEEP CONVECTION AND PRODUCING A GENERALLY FAIR WEATHER PATTERN ACROSS THE LOCAL ISLANDS. HOWEVER... OCCASIONAL BANDS AND PATCHES OF MOISTURE IN THE LOWEST 10K FEET WILL CONTINUE TO MOVE ACROSS THE LOCAL ISLANDS...RESULTING IN INTERVALS OF CLOUDINESS AND A FEW SHOWERS. AVIATION...AN AREA OF LOW LEVEL CLOUDS MAINLY BTWN 025-070 KFT ALONG WITH ACCOMPANYING SHOWERS EMBEDDED IN THE NORTHEAST FLOW WILL MOVE THROUGH PUERTO RICO AND THE U.S.VIRGIN ISLANDS THROUGH THE EARLY EVENING HOURS. MOSTLY VFR CONDITIONS WILL PREVAIL ACROSS THE LOCAL AIRPORTS...HOWEVER BRIEF MVFR CONDITIONS ACCOMPANYING THE LIGHT TO MODERATE PASSING SHOWERS WILL OCCUR IN SOME AREAS AT LEAST UNTIL 04/24Z. SOME OF THESE HEAVIER SHOWERS WILL PRODUCE GUSTY WINDS...AND THE LOW CLOUDS WILL OBSCURE MOUNTAIN TOPS ALONG THE CORDILLERA CENTRAL. LATEST INFORMATION FROM THE MONTSERRAT VOLCANO OBSERVATORY AS WELL AS SATELLITE IMAGERY INDICATED A FAINT ASH PLUME EXTENDING SOUTHWEST FROM THE ISLAND. THE CURRENT AND FORECAST WIND FLOW WILL MAINTAIN THE ASH PLUME AND GAS EMISSIONS WELL SOUTH OF THE LOCAL FLYING AREA. NO OTHER OPERATIONAL IMPACTS ARE FORECAST AT THIS TIME. PLEASE REFER TO LATEST VAAC (WASHINGTON) ADVISORIES FOR UPDATES. MARINE...GENERALLY EXPECT WINDS OF 17 KNOTS OR LESS AND SEAS OF 3 TO 7 FEET ACROSS THE REGIONAL WATERS THROUGH SATURDAY. THERE IS A PRECAUTIONARY STATEMENT FOR THE OFF SHORE WATERS OF THE ATLANTIC AND THE CARIBBEAN AND FOR THE ANEGADA AND MONA PASSAGES FOR TONIGHT. && .PRELIMINARY POINT TEMPS/POPS... SJU 72 83 73 84 / 40 40 40 40 STT 74 84 74 84 / 40 40 20 40 && .SJU WATCHES/WARNINGS/ADVISORIES... PR...NONE. VI...NONE. && $$ 72/04/