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| #41764 (Received by flhurricane at: 5:03 AM 25.Aug.2005) TCDAT2 TROPICAL STORM KATRINA DISCUSSION NUMBER 7 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT THU AUG 25 2005 KATRINA IS GENERATING STRONG CONVECTION WITH TOPS COLDER THAN -80C. HOWEVER...THE RADAR APPEARANCE HAS BEEN SOMEWHAT RAGGED...WITH THE CENTER NEAR THE EDGE OF THE CONVECTION AND NO EVIDENCE OF THE EYE STRUCTURE SEEN AROUND 00Z. RECENT DOPPLER RADAR DATA SHOWS THAT AN INNER WIND CORE IS PRESENT...WHICH MAY BE THE SAME FEATURE SEEN IN THE EARLIER RECONNAISSANCE FLIGHT. SATELLITE INTENSITY ESTIMATES FROM ALL AGENCIES ARE 45 KT...SO THAT REMAINS THE INITIAL INTENSITY. THE INITIAL MOTION IS 275/7. KATRINA REMAINS SOUTH OF A COMPLEX WEAKNESS IN THE SUBTROPICAL RIDGE. THE LOW LEVEL RIDGE HAS ONLY A SLIGHT WEAKNESS...WITH THE ASSOCIATED FLOW TRYING TO PUSH KATRINA TOWARD THE WEST-NORTHWEST. THE MID/UPPER-LEVEL RIDGE HAS A MORE PRONOUNCED WEAKNESS ASSOCIATED WITH A TROUGH OVER THE EASTERN UNITED STATES AND RIDGE ALONG THE GULF COAST. THE FLOW ASSOCIATED WITH THESE FEATURES IS TRYING TO PUSH KATRINA TOWARD THE SOUTHWEST. TRACK MODEL GUIDANCE RESPONDS TO THIS PATTERN WITH A SPREAD OF LANDFALLS IN FLORIDA FROM THE KEYS TO NORTH OF LAKE OKEECHOBEE. AFTER CROSSING FLORIDA...THE GUIDANCE HAS COME INTO SOMEWHAT BETTER AGREEMENT THAT KATARINA WILL TURN NORTHWARD IN RESPONSE TO A DEEPENING TROUGH OVER THE CENTRAL UNITED STATES...ALTHOUGH THERE IS STILL A NOTABLE SPREAD. THE NEW FORECAST TRACK IS AN UPDATE OF THE PREVIOUS PACKAGE AND IS DOWN THE MIDDLE OF THE ENVELOP OF MODEL GUIDANCE. KATRINA HAS BEEN BATTLING DRY AIR INTRUSION AND POSSIBLE NORTHERLY SHEAR UNDERCUTTING THE OUTFLOW LAYER...WHICH HAS PREVENTED THE CONVECTION FROM WRAPPING AROUND THE CENTER DURING THE NIGHT. SOME NORTHERLY TO NORTHEASTERLY SHEAR WILL LIKELY CONTINUE UNTIL KATRINA MAKES LANDFALL IN FLORIDA...WHICH WOULD SLOW DEVELOPMENT. ON THE OTHER HAND...THE COLD TOPS AND THE INNER WIND CORE SUGGEST THE POSSIBILITY OF STRENGTHENING. BASED ON THIS...THE INTENSITY FORECAST CALLS FOR KATRINA TO BECOME A HURRICANE BEFORE LANDFALL. KATRINA SHOULD WEAKEN WHILE SLOWLY CROSSING THE FLORIDA PENINSULA...THE RE-INTENSIFY UNDER LIGHT SHEAR CONDITIONS OVER THE GULF OF MEXICO. FORECASTER BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 25/0900Z 26.2N 78.7W 45 KT 12HR VT 25/1800Z 26.2N 79.4W 55 KT 24HR VT 26/0600Z 26.3N 80.4W 65 KT...INLAND 36HR VT 26/1800Z 26.3N 81.4W 45 KT...INLAND 48HR VT 27/0600Z 26.5N 82.5W 40 KT...OVER WATER 72HR VT 28/0600Z 27.5N 84.0W 50 KT 96HR VT 29/0600Z 29.5N 85.0W 70 KT 120HR VT 30/0600Z 33.0N 83.0W 30 KT...INLAND |
