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| #37549 (Received by flhurricane at: 10:34 PM 04.Aug.2005) TCDAT4 TROPICAL DEPRESSION NINE DISCUSSION NUMBER 2 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 PM EDT THU AUG 04 2005 THE CENTER OF TROPICAL DEPRESSION NINE IS A LITTLE DIFFICULT TO LOCATE THIS EVENING. AN SSM/I OVERPASS AT 2245Z AND SHORTWAVE IR IMAGERY FROM METEOSAT-8 SUGGEST THAT THE CYCLONE CENTER IS ELONGATED NORTH-NORTHEAST TO SOUTH-SOUTHWEST...WITH SATELLITE FIXES FROM TAFB AND SAB FALLING NEAR THE SOUTH-SOUTHWEST END. IT IS POSSIBLE THAT THE MEAN CENTER IS TO THE NORTH AND EAST OF THE ADVISORY POSITION. OVERPASSES FROM THE TRMM AND AQUA SATELLITES LATER TONIGHT MAY HELP RESOLVE THE ISSUE. DEEP CONVECTION IS CURRENTLY SOMEWHAT DISORGANIZED...SO THE INITIAL INTENSITY REMAINS 25 KT IN AGREEMENT WITH SATELLITE INTENSITY ESTIMATES. THE INITIAL MOTION IS AN SOMEWHAT UNCERTAIN 280/11. THE DEPRESSION IS ON THE SOUTH SIDE OF A DEEP-LAYER RIDGE. LARGE-SCALE MODELS FORECAST THIS SHOULD BE THE CASE FOR THE NEXT 3 DAYS...WHICH SHOULD PRODUCE A GENERAL WESTWARD TO WEST-NORTHWESTWARD MOTION. AFTER THAT...THE CYCLONE COULD BE APPROACHING A WEAKNESS IN THE RIDGE IN THE MID-ATLANTIC...WHICH WOULD ALLOW A MORE NORTHERLY MOTION. THE OFFICIAL FORECAST TRACK FOLLLOWS THIS SCENARIO AND IS AN UPDATE OF THE PREVIOUS FORECAST. IT SHOULD BE NOTED THAT THE 18Z GFS MODEL DID NOT APPEAR TO INITIALIZE THE CYCLONE WELL...WHILE THE 18Z NOGAPS MODEL DISSIPATED THE SYSTEM IN LESS THAN 72 HR. LARGE-SCALE MODELS FORECAST LIGHT VERTICAL SHEAR ALONG THE FORECAST TRACK DURING THE NEXT FIVE DAYS. THUS...THE BIGGEST CONTROL ON THE INTENSITY SHOULD BE SEA SURFACE TEMPERATURES. THE CENTER OF THE CYCLONE IS CURRENTLY OVER 27C WATER...WHILE REPORTS IN THE NORTHEASTERN PART OF THE CIRCULATION SHOW 26C WATER. COMBINE THIS WITH THE BROAD CIRCULATION AND THE INITIAL INTENSIFICATION SHOULD SOMEWHAT SLOW...PERHAPS EVEN SLOWER THAN CURRENTLY FORECAST. THE FORECAST TRACK BRINGS THE SYSTEM TO 28C WATER BY 72 HR...WHICH COULD ALLOW MORE STRENGTHENING THAN CURRENTLY FORECAST. HOWEVER... ANY MOTION TO THE RIGHT OF THE TRACK WOULD DELAY THE ARRIVAL OVER WARMER WATER AND SLOW INTENSIFICATION. THE INTENSITY FORECAST COMPROMISES BETWEEN THESE EXTREMES AND IS SIMILAR TO...BUT STRONGER THAN...THE SHIPS MODEL. THE WIND RADII FORECAST AT 72 HR HAS BEEN REVISED BASED ON CLIMATOLOGY AND THE BROAD CYCLONIC ENVELOPE OF THE DEPRESSION. FORECASTER BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 05/0300Z 13.0N 35.2W 25 KT 12HR VT 05/1200Z 13.3N 36.8W 30 KT 24HR VT 06/0000Z 13.7N 38.9W 40 KT 36HR VT 06/1200Z 14.3N 41.1W 45 KT 48HR VT 07/0000Z 14.9N 43.2W 55 KT 72HR VT 08/0000Z 16.5N 47.0W 65 KT 96HR VT 09/0000Z 18.5N 50.5W 75 KT 120HR VT 10/0000Z 20.5N 54.0W 75 KT |
