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| #47367 (Received by flhurricane at: 11:14 PM 20.Sep.2005) TCDAT3 HURRICANE RITA DISCUSSION NUMBER 14 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 PM EDT TUE SEP 20 2005 DATA FROM AN AIR FORCE RESERVE UNIT RECON AIRCRAFT AT 21/0020Z IN THE NORTHEAST QUADRANT INDICATED 700 MB FLIGHT-LEVEL WINDS OF 103 KT...ROUGHLY 93 KT SURFACE WINDS. DOPPLER RADAR VELOCITIES FROM KEY WEST HAVE BEEN AS HIGH AS 113 KT AT 9500 FEET IN SPOTS...WITH THE MAJORITY OF THE HIGHEST VALUES IN THE 105-107 KT RANGE...WHICH EQUALS ABOUT 95 KT SURFACE WINDS. A RECON PASS THROUGH THE 28 NMI DIAMETER EYE AT 0204Z INDICATED A SURFACE PRESSURE OF 965 MB... WHICH ROUGHLY EQUALS 95 KT. THEREFORE...THE INITIAL INTENSITY HAS BEEN INCREASED TO 95 KT...OR JUST BELOW MAJOR HURRICANE STRENGTH. THE INITIAL MOTION IS 275/11. RITA IS EXPECTED TO CONTINUE MOVING A LITTLE NORTH OF DUE WEST FOR THE NEXT 36-48 HOURS AS THE STRONG RIDGE TO THE NORTH REMAINS INTACT ALONG THE GULF COAST AND INTO CENTRAL AND NORTHERN TEXAS. THE 18Z GFS AND GFS-ENSEMBLE MODELS HAVE SHIFTED EASTWARD TO NEAR THE TEXAS-LOUISIANA BORDER. HOWEVER ...BOTH MODELS WERE FORECASTING THE 21/00Z 500 MB HEIGHTS ACROSS TEXAS TO DECREASE BY 20 METERS...WHEN IN FACT... 21/00Z UPPER-AIR DATA INDICATE THE HEIGHTS DID NOT CHANGE AND THE MID-LEVEL HIGH OVER NORTHWEST TEXAS HAS REMAINED QUITE STRONG WITH HEIGHTS NEAR 6000 METERS. AS A RESULT...LESS WEIGHT WAS PALCED ON THE GFS MODEL ...SINCE IT APPEARS TO BE DECREASING THE STRENGTH OF THE RIDGE TOO QUICKLY...THE OFFICIAL FORECAST TRACK IS JUST AN UPDATE AND EXTENSION OF THE PREVIOUS ADVISORY TRACK...AND IS CLOSE TO THE NHC MODEL CONSENSUS. THE PREVIOUS ADVISORY INDICATING RAPID INTENSIFICATION FOR THE NEXT 24 HOURS APPEARS TO BE ON TRACK. DURING THE PAST 14 HOURS...THE CENTRAL PRESSURE HAS DECREASED 20 MB...OR AT A RATE OF ABOUT 2 DVORAK T-NUMBERS PER 24 HOURS. WHILE SUCH A LARGE PRESSURE FALL TREND RARELY OCCURS FOR MORE THAN 24 HOURS...THE VERY FAVORABLE UPPER-LEVEL OUTFLOW PATTERN AND 30C-31C SSTS BENEATH RITA SUGGEST THAT RAPID INTENSIFICATION SHOULD CONTINUE FOR AT LEAST ANOTHER 24 HOURS. A POLEWARD OUTFLOW CHANNEL IS WELL ESTABLISHED WITH OUTFLOW ACCUMULATING INTO A LARGE UPPER-LEVEL LOW...OR MASS SINK...EAST OF THE BAHAMAS. IN ADDITION... AN EQUATORWARD OUTFLOW CHANNEL ALSO APPEARS TO BE DEVELOPING. GIVEN THE DUAL OUTFLOW PATTERN THAT IS EXPECTED TO PERSIST FOR THE NEXT 36-48 HOURS...STRENGTHENING INTO A CATEGORY 5 HURRICANE IS A DISTINCT POSSIBILITY. BY 72 HOURS... A GRADUAL INCREASE IN THE SOUTHWESTERLY VERTICAL SHEAR IS EXPECTED TO BRING ABOUT SOME WEAKENING. HOWEVER...THE GFS-BASED SHIPS MODEL THAT IS INDICATING 25-30 KT OF SHEAR MAY BE INCLUDING THE WINDS ASSOCIATED WITH THE STRONG OUTFLOW PATTERN DEPICTED BY THE MODEL. THIS WOULD MEAN THAT THE GFS SHEAR IS TOO HIGH...AND THUS...THE SHARP GFS WEAKENING OF RITA DOWN TO 99 KT AT LANDFALL WOULD BE PREMATURE. THE OFFICIAL INTENSITY FORECAST LEANS CLOSER TO THE FSU SUPERENSEMBLE INTENSITY FORECAST OF 122 KT IN 48 HOURS AND 126 KT IN 60 HOURS. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 21/0300Z 24.1N 83.2W 95 KT 12HR VT 21/1200Z 24.2N 85.2W 105 KT 24HR VT 22/0000Z 24.4N 87.5W 120 KT 36HR VT 22/1200Z 24.6N 89.4W 125 KT 48HR VT 23/0000Z 25.1N 91.4W 125 KT 72HR VT 24/0000Z 27.1N 94.7W 120 KT 96HR VT 25/0000Z 30.5N 96.5W 60 KT...INLAND 120HR VT 26/0000Z 34.5N 96.5W 25 KT...DISSIPATING INLAND |
