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| #47001 (Received by flhurricane at: 5:00 PM 19.Sep.2005) TCDAT3 TROPICAL STORM RITA DISCUSSION NUMBER 8 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 PM EDT MON SEP 19 2005 RITA IS CLOSE TO HURRICANE STATUS... BUT IT IS NOT QUITE THERE YET. THE STORM IS PRODUCING SOME VERY DEEP CONVECTION NEAR THE CENTER... BANDING FEATURES IN THE NORTHERN AND EASTERN QUADRANTS...AND INCREASINGLY WELL-ESTABLISHED OUTFLOW INDICATING LESSENING SHEAR. THE OVERALL EXTENT OF DEEP CONVECTION HAS DECREASED SOMEWHAT DURING THE PAST COUPLE OF HOURS...BUT THIS OFTEN OCCURS DURING THE AFTERNOON CONVECTIVE MINIMUM PERIOD. DATA FROM THE STEPPED FREQUENCY MICROWAVE RADIOMETER...SFMR...ONBOARD A NOAA HURRICANE HUNTER AIRCRAFT...RECENTLY INDICATED SURFACE WINDS AS STRONG AS 62 KT ABOUT 25 N MI SOUTHEAST OF THE CENTER. THE MINIMUM CENTRAL PRESSURE MEASURED BY DROPSONDE HAS BEEN HOLDING AT 994-995 MB... AND THE ADVISORY INTENSITY IS MAINTAINED AT 60 KT. RITA IS ON TRACK... AND AS ANTICIPATED IS MOVING A LITTLE FASTER TOWARD THE WEST-NORTHWEST...NOW AT 285/12. MODELS REMAIN IN TIGHT AGREEMENT THAT THIS MOTION WILL CHANGE LITTLE DURING THE NEXT COUPLE OF DAYS...EXCEPT FOR A SLIGHT BEND TO THE WEST INTO THE GULF OF MEXICO TO THE SOUTH OF THE MID LEVEL RIDGE ALONG ABOUT 30N. THE DYNAMICAL MODELS HAVE GENERALLY SHIFTED SLIGHTLY BACK TO THE LEFT OR WEST AT DAYS 3 THROUGH 5...BRINGING THE CONSENSUS INTO GOOD AGREEMENT WITH THE PREVIOUS ADVISORY. OVERALL THE NEW SUITE OF GUIDANCE PROVIDES LITTLE REASON TO MAKE ANY CHANGES TO THE OFFICIAL FORECAST TRACK... EXCEPT TO SPEED IT UP JUST SLIGHTLY. HOWEVER... THE SPREAD IN THE MODELS OVER THE GULF REMAINS SIGNIFICANT...SINCE IT IS NOT CLEAR IF THE RIDGE OVER THE SOUTHEASTERN U.S. WILL MIGRATE FAR ENOUGH EASTWARD LATE IN THE FORECAST PERIOD TO CURVE RITA NORTHWARD AROUND ITS WESTERN PERIPHERY. THE NOGAPS AND GFDN FORECAST A STRAIGHT WESTWARD TRACK INTO SOUTHERN TEXAS...WHILE THE GFS AND GFDL FORECAST A NORTHWARD BEND TOWARD THE TEXAS/LOUSIANA BORDER REGION. GIVEN THIS UNCERTAINTY...IT MUST AGAIN BE EMPHASIZED THAT FORECAST ERRORS CAN BE QUITE LARGE AT THESE LONGER LEAD TIMES. EVEN THOUGH RITA IS NOT YET A HURRICANE...CONDITIONS APPEAR CONDUCIVE FOR IT TO BECOME ONE SOON...PRIOR TO REACHING THE GULF OF MEXICO. INTENSIFICATION TO MAJOR HURRICANE STATUS OVER THE GULF OF MEXICO APPEARS PROBABLE...GIVEN THAT THE DYNAMICAL MODELS ARE FORECASTING A LARGE UPPER LEVEL ANTICYCLONE TO DOMINATE THE AREA AND PROVIDE AN ENVIRONMENT OF WEAK WIND SHEAR. ADDITIONALLY...OCEAN TEMPERATURES ARE QUITE WARM IN THE GULF...AND NOT JUST AT THE SURFACE. THE NEW OFFICIAL INTENSITY FORECAST IS BASICALLY AN UPDATE OF THE PREVIOUS ONE THROUGH DAY 3...THEN CALLING FOR A PEAK AT 105 KT OVER THE GULF IN ACCORDANCE WITH THE LATEST SHIPS GUIDANCE. THE GFDL AND FSU SUPERENSEMBLE FORECAST AN EVEN STRONGER HURRICANE OVER THE GULF...AND THIS IS CERTAINLY POSSIBLE. FORECASTER KNABB FORECAST POSITIONS AND MAX WINDS INITIAL 19/2100Z 23.3N 76.5W 60 KT 12HR VT 20/0600Z 23.7N 78.4W 75 KT 24HR VT 20/1800Z 24.2N 80.9W 85 KT 36HR VT 21/0600Z 24.6N 83.5W 95 KT 48HR VT 21/1800Z 24.9N 85.9W 100 KT 72HR VT 22/1800Z 25.5N 90.0W 105 KT 96HR VT 23/1800Z 27.5N 93.5W 105 KT 120HR VT 24/1800Z 30.0N 96.0W 70 KT...INLAND |
