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#53188 (Received by flhurricane at: 4:25 AM 23.Oct.2005) TCDAT5 TROPICAL STORM ALPHA DISCUSSION NUMBER 4 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT SUN OCT 23 2005 ALPHA DEVELOPED SOME MODEST BANDING AROUND 6Z...AND THE DVORAK INTENSITY ESTIMATE FROM TAFB CAUGHT UP WITH THE ADVISORY VALUE OF 45 KT. THE CONVECTIVE PATTERN IS ALREADY DEGRADING HOWEVER AS THE CENTER IS ABOUT TO MAKE LANDFALL IN HISPANIOLA. ALTHOUGH SURFACE OBSERVATIONS AT BARAHONA AND SANTO DOMINGO INDICATE THAT ALPHA HAS PROBABLY WEAKENED...I WILL LEAVE THE ADVISORY INTENSITY AT 45 KT TO BE ON THE SAFE SIDE. GIVEN THE VERY SMALL SIZE OF THE CIRCULATION...IT IS DIFFICULT TO IMAGINE IT SURVIVING THE MOUNTAINOUS TERRAIN AHEAD OF IT. ASSUMING THERE IS ANYTHING LEFT ON THE OTHER SIDE...INCREASING SOUTHERLY FLOW ON THE EAST SIDE OF WILMA IS LIKELY TO MAKE IT DIFFICULT FOR ALPHA TO MAINTAIN A CLOSED CIRCULATION. ALTHOUGH THE SHIPS AND GFDL MODELS INTENSIFY ALPHA IN THE ATLANTIC IN A LOW SHEAR ENVIRONMENT...NONE OF THE GLOBAL MODELS SHOW ANYTHING RESEMBLING A CLOSED SURFACE CIRCULATION. THE OFFICIAL FORECAST WILL CARRY ALPHA FOR 36 HOURS BUT I EXPECT IT TO DISSIPATE MUCH SOONER THAN THAT. THE INITIAL MOTION IS 305/12. ALPHA IS NEARING THE SOUTHWEST EDGE OF THE SUBTROPICAL RIDGE. AS THE LARGE CIRCULATION OF HURRICANE WILMA APPROACHES OVER THE NEXT 24 HOURS...ALPHA IS EXPECTED TO TURN NORTHWARD AND ACCELERATE. THE GLOBAL MODEL TRACKERS ARE LOCKING ON TO THE LOW-LEVEL VORTICITY MAXIMUM...WHICH IS A DEGREE OR TWO TO THE EAST OF THE SURFACE CIRCULATION IN THE MODELS. THE OFFICIAL FORECAST TRIES TO FOLLOW THE SURFACE CENTER...AND IS FAIRLY CLOSE TO THE MEDIUM BAM. ALPHA HAS THE POTENTIAL TO BE A SIGNIFICANT RAINFALL/FLOODING EVENT OVER HISPANIOLA...WITH A STRONG LIKLIHOOD OF LIFE-THREATENING FLASH FLOODS AND MUD-SLIDES. FORECASTER FRANKLIN FORECAST POSITIONS AND MAX WINDS INITIAL 23/0900Z 18.1N 71.0W 45 KT 12HR VT 23/1800Z 20.1N 72.4W 30 KT 24HR VT 24/0600Z 23.3N 73.5W 30 KT 36HR VT 24/1800Z 28.0N 73.5W 30 KT...DISSIPATING 48HR VT 25/0600Z...DISSIPATED |