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| #130794 (Received by flhurricane at: 5:00 PM 09.May.2007) TCDAT1 SUBTROPICAL STORM ANDREA DISCUSSION NUMBER 2 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL012007 500 PM EDT WED MAY 09 2007 THE ORGANIZATION OF ANDREA HAS DETERIORATED SOMEWHAT DURING THE PAST FEW HOURS...WITH A SIGNIFICANT DECREASE IN CONVECTION PARTICULARLY IN THE NORTHWESTERN QUADRANT. SOME BANDS OF DEEP CONVECTION PERSIST...HOWEVER...ELSEWHERE IN THE CIRCULATION...AND SHIP WBVY REPORTED 37 KT WINDS AT 18Z ABOUT 75 N MI NORTH-NORTHEAST OF THE CIRCULATION CENTER. THE NEXT RECONNAISSANCE AIRCRAFT WILL INVESTIGATE ANDREA TOMORROW MORNING...AND THE NEXT QUIKSCAT PASS OVER OR NEAR ANDREA WILL OCCUR NEAR 00Z THIS EVENING. IN THE MEANTIME...IT IS REASONABLE TO MAINTAIN THE INTENSITY AT 40 KT. ANDREA IS CURRENTLY OVER SSTS NO WARMER THAN ABOUT 25 CELSIUS...AND THE SLOW MOTION SHOWN IN THE TRACK FORECAST PROBABLY MEANS SOME EVEN COOLER WATERS WILL BE CHURNED UP FROM BENEATH THE SURFACE. THEREFORE...IN ACCORDANCE WITH ALL OF THE INTENSITY GUIDANCE...A WEAKENING TREND IS ANTICIPATED AND THE OFFICIAL FORECAST SHOWS DISSIPATION NEAR THE COAST IN LESS THAN FOUR DAYS. THE SLOPPY CIRCULATION MAKES IT DIFFICULT TO CONFIDENTLY DETERMINE THE INITIAL MOTION...BUT MY BEST ESTIMATE REMAINS SLOW AND GENERALLY WESTWARD OR 265/4. RECENT IMAGERY SUGGESTS THE SYSTEM MIGHT HAVE STARTED SAGGING TOWARD THE SOUTHWEST. THERE IS NO SIGNIFICANT CHANGE TO THE TRACK FORECAST OR THE SUPPORTING REASONING. SINCE ANDREA IS TRAPPED WITHIN A LARGE MIDDLE- TO UPPER-LEVEL TROUGH THAT THE DYNAMICAL MODELS FORECAST TO NOT MOVE MUCH DURING THE NEXT COUPLE OF DAYS...A SLOW AND GENERALLY SOUTHWARD MOTION IS FORECAST. BEYOND THAT TIME...SOME OF THE MODELS FORECAST THE LOW-LEVEL CIRCULATION TO DECOUPLE FROM THE DECAYING MIDDLE- AND UPPER-LEVEL VORTICITY MAXIMA...SO THE OFFICIAL FORECAST INDICATES A NEARLY STATIONARY AND DISSIPATING SYSTEM NEAR THE COAST BY 72 HOURS. GIVEN THE UNCERTAINTIES IN THE FORECAST TRACK...INTENSITY...AND WIND RADII... THE TROPICAL STORM WATCH IS UNCHANGED FROM THIS MORNING. FORECAST POSITIONS AND MAX WINDS INITIAL 09/2100Z 30.8N 80.1W 40 KT 12HR VT 10/0600Z 30.6N 80.6W 35 KT 24HR VT 10/1800Z 30.2N 80.8W 35 KT 36HR VT 11/0600Z 29.8N 80.9W 30 KT 48HR VT 11/1800Z 29.5N 80.9W 30 KT 72HR VT 12/1800Z 29.5N 80.9W 25 KT...DISSIPATING 96HR VT 13/1800Z...DISSIPATED $$ FORECASTER KNABB |
