|
Show Selection: |
| #47649 (Received by flhurricane at: 4:46 AM 22.Sep.2005) TCDAT3 HURRICANE RITA DISCUSSION NUMBER 19 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT THU SEP 22 2005 IF RITA HAS NOT PEAKED IN INTENSITY...IT LOOKS LIKE IT IS PRETTY CLOSE TO DOING SO. THE LATEST CENTRAL PRESSURE ESTIMATED FROM RECONNAISSANCE AIRCRAFT DATA IS 897 MB...WHICH SHOWS LITTLE CHANGE DURING THE PAST 8 HR. THE MAXIMUM FLIGHT-LEVEL WINDS SO FAR ARE 165 KT IN THE NE EYEWALL...WHICH IS ONLY SLIGHTLY HIGHER THAN THE 161 KT OBSERVED YESTERDAY AFTERNOON. THE AIRCRAFT DATA SHOWS A INCREASINGLY STRONG OUTER WIND MAXIMUM THAT IS LIKELY THE START OF A CONCENTRIC EYEWALL CYCLE...AND SATELLITE IMAGERY SINCE THE END OF THE ECLIPSE PERIOD SHOWS WARMING OF THE CONVECTION NEAR THE CENTER. BASED ON ALL OF THIS...THE INITIAL INTENSITY REMAINS 150 KT. RITA HAS TURNED A LITTLE TO THE RIGHT DURING THE PAST SEVERAL HOURS AND THE INITIAL MOTION IS NOW 285/8. RAWINSONDE DATA SHOWS A STRONG MID-LEVEL RIDGE CENTERED OVER TEXAS. LARGE-SCALE MODELS FORECAST THIS RIDGE TO SHIFT EASTWARD INTO THE SOUTHEASTERN STATES AND THE EASTERN GULF OF MEXICO DURING THE NEXT 48 HR. THIS SHOULD ALLOW RITA TO TURN MORE NORTHWARD WITH TIME. THE TRACK GUIDANCE IS NOW CLUSTERED AROUND A LANDFALL BETWEEN THE SABINE RIVER AND MATAGORDA TEXAS IN 48-60 HR...WITH A NET EASTWARD SHIFT OF THE GUIDANCE SINCE THE LAST PACKAGE. THE NEW FORECAST TRACK IS ALSO SHIFTED EASTWARD ABOUT 30 N MI...CALLING FOR LANDFALL NEAR THE BOLIVAR PENINSULA AND GALVESTON BAY. HOWEVER...IT SHOULD BE NOTED THAT THE NEW TRACK IS ALONG THE LEFT OR WEST SIDE OF THE ENVELOPE OF GUIDANCE. THE INTENSITY FORECAST REMAINS SOMEWHAT PROBLEMATIC. FIRST...THE MORE NORTHERLY TRACK WILL LIKELY KEEP RITA OVER THE LOOP CURRENT LONGER THAN PREVIOUSLY EXPECTED...SO THE EFFECT OF LOWER OCEAN HEAT CONTENT MAY BE SOMEWHAT LESS THAN PREVIOUSLY EXPECTED IN THE FIRST 24 HR OR SO. SECOND...THE GFS AND SHIP MODELS FORECAST SIGNIFICANT SHEAR OVER RITA AFTER 24 HR...WHICH RESULTS IN SHIPS CALLING FOR SIGNIFICANT WEAKENING. SHEAR ANALYSES FROM CIMSS AT THE UNIVERSITY OF WISCONSIN SHOW ABOUT 12 KT OF SOUTHERLY SHEAR CAUSED BY AN UPPER-LEVEL ANTICYCLONE EAST OF RITA...AND THE LARGE-SCALE MODELS SUGGEST THIS PATTERN WILL CONTINUE UNTIL LANDFALL. HOWEVER...THE GFS AND SHIPS MAY BE OVERDOING THE SHEAR. FINALLY...THERE WILL BE AT LEAST ONE AND POSSIBLE MORE CONCENTRIC EYEWALL CYCLES BEFORE LANDFALL. THE INTENSITY FORECAST IS BASED ON THE PREMISE THAT SHEAR AND REDUCED OUTFLOW WILL CAUSE A GRADUAL WEAKENING... ESPECIALLY AFTER RITA MOVES WEST OF THE LOOP CURRENT IN 24-36 HR. SUPERIMPOSED ON TOP OF THIS WILL BE FLUCTUATIONS CAUSED BY CONCENTRIC EYEWALL CYCLES. THE NEW INTENSITY FORECAST IS AN UPDATE OF THE PREVIOUS FORECAST...CALLING FOR SLOW OVERALL WEAKENING BUT NOT AS MUCH AS SHOWN BY SHIPS. FORECASTER BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 22/0900Z 24.9N 88.0W 150 KT 12HR VT 22/1800Z 25.3N 89.3W 150 KT 24HR VT 23/0600Z 26.1N 91.1W 145 KT 36HR VT 23/1800Z 27.2N 92.8W 140 KT 48HR VT 24/0600Z 28.8N 94.3W 130 KT 72HR VT 25/0600Z 32.0N 95.5W 65 KT...INLAND 96HR VT 26/0600Z 34.1N 95.0W 30 KT...INLAND 120HR VT 27/0600Z 34.5N 94.5W 25 KT...INLAND DISSIPATING |
