000 WTNT41 KNHC 120849 TCDAT1 TROPICAL STORM PATTY DISCUSSION NUMBER 4 NWS NATIONAL HURRICANE CENTER MIAMI FL AL162012 500 AM EDT FRI OCT 12 2012 CONVENTIONAL SATELLITE IMAGERY INDICATES THAT PATTY CONTINUES TO GENERATE A LARGE MASS OF DEEP CONVECTION. HOWEVER...AN EARLIER SSMIS PASS AND NIGHTTIME VISIBLE IMAGES SHOW THE WELL-DEFINED LOW-LEVEL CENTER EXPOSED ABOUT 60 N MI SOUTHWEST OF THE NEAREST DEEP CONVECTION AS A CONSEQUENCE OF STRONG SOUTHWESTERLY SHEAR. DVORAK T-NUMBERS HAVE ABRUPTLY DECREASED TO 2.0 FROM BOTH SATELLITE AGENCIES...AND A BLEND OF T- AND CI-NUMBERS IS THE BASIS FOR LOWERING THE INITIAL INTENSITY TO 35 KT. PATTY IS NOT LIKELY TO HANG ON AS A TROPICAL CYCLONE FOR MUCH LONGER. AN INCREASINGLY DRIER AND MORE STABLE AIR MASS IS WRAPPING AROUND THE CIRCULATION OF THE STORM DUE ITS PROXIMITY TO A FRONT. IN ADDITION...A BUILDING LOW-LEVEL RIDGE OVER WESTERN ATLANTIC AND STRONG SOUTHWESTERLY FLOW ALOFT WILL RESULT IN EVEN STRONGER VERTICAL SHEAR OVER PATTY DURING THE NEXT DAY OR SO. THESE FACTORS SHOULD PROMOTE WEAKENING...AND PATTY IS LIKELY TO BE SHEARED APART AND BECOME A REMNANT LOW WITHIN 24-36 HOURS...IF NOT SOONER. THE NHC INTENSITY FORECAST IS REDUCED FROM THE PREVIOUS ONE AND A BIT LOWER THAN THE STATISTICAL-DYNAMICAL GUIDANCE. SATELLITE DATA SUGGEST THAT THE CENTER OF PATTY IS FARTHER SOUTH THAN PREVIOUSLY ESTIMATED...AND HAS BEEN DRIFTING TOWARD THE SOUTH- SOUTHWEST...OR 200/03...DURING THE LAST SEVERAL HOURS. THE MODEL GUIDANCE SHOWS THE INCREASINGLY SHALLOW CYCLONE BEING PUSHED SOUTHWESTWARD BY THE BUILDING SURFACE RIDGE OVER THE WESTERN ATLANTIC DURING THE NEXT FEW DAYS...EXCEPT FOR THE ECMWF AND UKMET MODELS THAT DISSIPATE THE STORM RELATIVELY SOON. THE NHC TRACK FORECAST IS SIMILAR TO THE PREVIOUS ONE...BUT A BIT FASTER TOWARD THE SOUTHWEST THROUGH 36 HOURS. FORECAST POSITIONS AND MAX WINDS INIT 12/0900Z 25.1N 72.5W 35 KT 40 MPH 12H 12/1800Z 24.9N 72.8W 30 KT 35 MPH 24H 13/0600Z 24.6N 73.1W 30 KT 35 MPH 36H 13/1800Z 24.3N 73.5W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 14/0600Z 23.9N 74.4W 20 KT 25 MPH...POST-TROP/REMNT LOW 72H 15/0600Z 23.0N 78.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 16/0600Z...DISSIPATED $$ FORECASTER KIMBERLAIN