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#458271 (Received by flhurricane at: 10:52 PM 09.Sep.2011) TCDAT5 TROPICAL STORM NATE DISCUSSION NUMBER 10 NWS NATIONAL HURRICANE CENTER MIAMI FL AL152011 1000 PM CDT FRI SEP 09 2011 THERE HAS NOT BEEN A LOT OF CHANGE WITH THE STRUCTURE OF NATE DURING THE PAST SEVERAL HOURS. ALTHOUGH THE CYCLONE CONTINUES TO HAVE CURVED BANDING FEATURES ON THE SABANCUY RADAR...THE ASSOCIATED CONVECTION IS NOT VERY DEEP AND THE CENTER HAS A HOLLOW APPEARANCE ON INFRARED SATELLITE PICTURES. THE INITIAL WINDS ARE KEPT AT 45 KT...AND AN AIR FORCE RESERVE PLANE WILL BE IN THE AREA AROUND 0600 UTC TO OBTAIN A BETTER ESTIMATE. SATELLITE IMAGES SUGGEST THAT NATE HAS MOVED A LITTLE BIT TONIGHT... WITH AN INITIAL MOTION ESTIMATE OF 280/2. A RIDGE IS FORECAST TO BUILD TO THE NORTH OF NATE...CAUSING THE STORM TO ACCELERATE TO THE WEST TOMORROW. A FAIR NUMBER OF THE MODELS ALSO SUGGEST A SOUTH-OF-WEST MOTION COULD OCCUR AS THE CYCLONE APPROACHES LAND...WHICH IS NOT UNCOMMON IN THAT PART OF THE SOUTHWESTERN GULF OF MEXICO. THE NEW NHC TRACK IS ADJUSTED A SMIDGE TO THE SOUTH AND IS A LITTLE FASTER THAN THE PREVIOUS FORECAST...THOUGH IT REMAINS TO THE NORTH OF THE MODEL CONSENSUS. NATE IS YET ANOTHER EXAMPLE OF THE LIMITATIONS OF INTENSITY FORECASTING. DESPITE A SEEMINGLY FAVORABLE ENVIRONMENT AND ALL MODELS SUGGESTING STRENGTHENING...THE STORM HAS LOST ORGANIZATION SINCE THIS TIME YESTERDAY. ONE REASON COULD BE THAT THE STATIONARY SYSTEM HAS UPWELLED COOLER WATERS...CAUSING A LACK OF INSTABILITY NEAR THE CENTER...WHICH SEEMS LIKE A GOOD POSSIBILITY GIVEN THE DEARTH OF CENTRAL CONVECTION. DRY AIR ALOFT ALSO MAY HAVE PLAYED A ROLE...THOUGH LITTLE EVIDENCE CAN BE SEEN IN SSM/IS VAPOR IMAGES. IN ANY CASE...NATE IS FORECAST TO MOVE A LITTLE FASTER OVERNIGHT... WHICH SHOULD BRING THE STORM OVER WARMER WATERS. WITH LIGHT SHEAR CONDITIONS LIKELY...SOME INTENSIFICATION IS THE BEST BET. THE MODELS DO SHOW STRENGTHENING...THOUGH THEY HAVE BACKED OFF OF THE PEAK INTENSITY AND ALMOST ALL OF THEM KEEP NATE BELOW HURRICANE STRENGTH BEFORE LANDFALL. THIS REDUCTION SEEMS REASONABLE GIVEN THAT NATE IS FORECAST TO SPEND LESS TIME OVER WATER. THUS THE INTENSITY FORECAST IS DECREASED FROM THE PREVIOUS ADVISORY...THOUGH IT REMAINS ABOVE THE INTENSITY CONSENSUS. FORECAST POSITIONS AND MAX WINDS INIT 10/0300Z 20.1N 93.2W 45 KT 50 MPH 12H 10/1200Z 20.2N 93.8W 45 KT 50 MPH 24H 11/0000Z 20.1N 94.7W 55 KT 65 MPH 36H 11/1200Z 20.0N 95.5W 60 KT 70 MPH 48H 12/0000Z 19.8N 96.8W 55 KT 65 MPH...INLAND 72H 13/0000Z 19.5N 99.5W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 14/0000Z...DISSIPATED $$ FORECASTER BLAKE/BEVEN |