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| #46941 (Received by flhurricane at: 11:08 AM 19.Sep.2005) TCDAT3 TROPICAL STORM RITA DISCUSSION NUMBER 7 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 AM EDT MON SEP 19 2005 SINCE THE LAST RECON FIX SHORTLY BEFORE 12Z...WHICH MEASURED A 997 MB CENTRAL PRESSURE...VERY DEEP CONVECTION HAS WRAPPED AROUND THE LOW LEVEL CENTER...SO RITA IS DEVELOPING SUBSTANTIAL INNER CORE CONVECTION FOR THE FIRST TIME. DVORAK INTENSITY ESTIMATES AT 12Z WERE UNANIMOUSLY T3.5/55 KT...WHICH IS THE ADVISORY INTENSITY. RECON IS SCHEDULED TO BE BACK INTO THE SYSTEM EARLY THIS AFTERNOON. RITA IS MOVING TOWARD THE WEST-NORTHWEST OR 285 DEGREES AT ABOUT 10 KNOTS...TO THE SOUTH OF THE EASTERN EXTENSION OF A STRONG MID-LEVEL RIDGE CENTERED OVER TEXAS. DYNAMICAL MODELS ARE IN VERY TIGHT AGREEMENT THROUGH 36 HOURS ON BASICALLY THIS CONTINUED HEADING...WITH PERHAPS A SLIGHT INCREASE IN FORWARD SPEED AS THE RIDGE TO THE NORTH STRENGTHENS AND THE TROPICAL CYCLONE DEEPENS. MOST OF THE MODELS AND THEIR CONSENSUS HAVE SHIFTED NORTHWARD...AND THE OFFICIAL FORECAST IS ADJUSTED LIKEWISE...BRINGING THE TRACK CLOSER TO THE FLORIDA KEYS THAN THE PREVIOUS ADVISORY. ADDITIONALLY...MOST OF THE MODELS HAVE SHIFTED FARTHER NORTH LATE IN THE FORECAST PERIOD OVER THE WESTERN GULF OF MEXICO...DUE TO A WEAKENING RIDGE AS A TROUGH APPROACHES FROM THE WESTERN UNITED STATES IN SEVERAL DAYS. THE OFFICIAL FORECAST IS ADJUSTED TO THE NORTH OR RIGHT OVER THE GULF...BUT NOT AS FAR AS THE MODEL CONSENSUS. RECON DATA AND SURFACE OBSERVATIONS INDICATE THE SIZE OF THE STORM IS INCREASING...ESPECIALLY TO THE NORTH OF THE CENTER. THE FORECAST WIND RADII ARE EXPANDED BASED ON THESE DATA...WIND RADII CLIPER GUIDANCE...AND GLOBAL MODELS DEPICTING AN EXPANDING SYSTEM. IT IS IMPORTANT TO EMPHASIZE THAT RITA COULD AFFECT A LARGE AREA AND ONE SHOULD NOT FOCUS ON THE EXACT TRACK. ATMOSPHERIC CONDITIONS ARE CONTINUING TO BECOME MORE CONDUCIVE FOR STRENGTHENING...AND ALL FORECAST GUIDANCE SUGGESTS RITA SHOULD INTENSIFY SOME MORE...BEFORE AND AFTER IT REACHES THE GULF OF MEXICO. THE NEW OFFICIAL INTENSITY FORECAST IS ADJUSTED UPWARD AND IS A BLEND BETWEEN THE SHIPS AND GFDL GUIDANCE THROUGH DAY 3...AND SHOWS RITA REACHING CATEGORY TWO STATUS BEFORE REACHING THE GULF OF MEXICO. THERE IS A SLIGHT POSSIBILITY IT COULD STRENGTHEN FASTER THAN FORECAST. ALL INDICATIONS ARE THAT RITA WILL BECOME A MAJOR HURRICANE OVER THE GULF OF MEXICO... WHERE A LARGE UPPER LEVEL ANTICYCLONE IS FORECAST BY THE MODELS TO DOMINATE AND PROVIDE A WEAK SHEAR ENVIRONMENT. FORECASTER KNABB FORECAST POSITIONS AND MAX WINDS INITIAL 19/1500Z 23.0N 75.2W 55 KT 12HR VT 20/0000Z 23.4N 76.9W 70 KT 24HR VT 20/1200Z 24.0N 79.4W 80 KT 36HR VT 21/0000Z 24.4N 81.9W 90 KT 48HR VT 21/1200Z 24.7N 84.5W 95 KT 72HR VT 22/1200Z 25.5N 88.5W 100 KT 96HR VT 23/1200Z 26.5N 92.5W 100 KT 120HR VT 24/1200Z 29.0N 95.0W 100 KT |
