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| #51960 (Received by flhurricane at: 11:03 PM 15.Oct.2005) TCDAT4 TROPICAL DEPRESSION TWENTY-FOUR DISCUSSION NUMBER 2 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 PM EDT SAT OCT 15 2005 THE CYCLONE IS STILL IN THE FORMATIVE STAGES AND DOES NOT YET HAVE VERY MUCH DEEP CONVECTION NEAR THE CIRCULATION CENTER... BUT OUTER BANDING FEATURES SEEM TO BE GRADUALLY CONSOLIDATING. THE CYCLONIC CIRCULATION ENVELOPE IS WELL-ESTABLISHED... AS IS UPPER LEVEL ANTICYCLONIC OUTFLOW. A 23Z QUIKSCAT OVERPASS HAD SOME 30-35 KT VECTORS THAT ARE PROBABLY RAIN CONTAMINATED... SO THE ADVISORY INTENSITY REMAINS 25 KT. THE DEPRESSION HAS BEEN DRIFTING SOUTHWESTWARD FOR THE PAST FEW HOURS...AT ABOUT 225/3. THE WEAK STEERING RESULTS FROM THE DEPRESSION BEING STUCK BETWEEN MID-LEVEL RIDGES CENTERED OVER THE WESTERN GULF OF MEXICO AND THE CENTRAL TROPICAL ATLANTIC OCEAN. THIS RELATIVE WEAKNESS IN THE RIDGING IS ASSOCIATED WITH A MIDLATITUDE LOW PRESSURE SYSTEM NEAR THE NEW ENGLAND STATES. THE FLOW AROUND THE GULF RIDGE APPEARS TO HAVE A SLIGHTLY GREATER INFLUENCE FOR NOW... AND THE DYNAMICAL MODELS FORECAST THE GULF RIDGE TO REMAIN IN PLACE FOR THE NEXT COUPLE OF DAYS. THEREAFTER... THE MODELS SHOW THE GULF RIDGE MIGRATING WESTWARD... LEAVING A GROWING WEAKNESS OVER THE EASTERN GULF AND ALLOWING THE WESTWARD-BUILDING RIDGE OVER THE ATLANTIC TO BEGIN PUSHING THE TROPICAL CYCLONE NORTHWARD. SINCE THIS PATTERN CHANGE IS FORECAST TO OCCUR SO GRADUALLY... NONE OF THE GLOBAL MODELS... EXCEPT FOR THE CANADIAN... FORECAST THE TROPICAL CYCLONE TO LEAVE THE WESTERN CARIBBEAN SEA WITHIN THE NEXT FIVE DAYS. THE OFFICIAL FORECAST IS SOUTH OF THE PREVIOUS ADVISORY FOR THE FIRST COUPLE OF DAYS TO ADJUST FOR THE INITIAL MOTION... THEN BACK ON TRACK THEREAFTER... AND CLOSE TO A BLEND OF THE GFS AND GFDL. ATMOSPHERIC AND OCEANIC CONDITIONS APPEAR CONDUCIVE FOR STRENGTHENING. EVEN THOUGH THE FORWARD MOTION WILL BE SLOW... THE LARGE OCEANIC HEAT CONTENT SHOULD CONTINUE TO SUPPLY FUEL FOR INTENSIFICATION WHILE VERTICAL SHEAR REMAINS WEAK BENEATH A LARGE UPPER-LEVEL ANTICYCLONE. THE COUPLED GFDL SYSTEM FORECASTS A HURRICANE IN ABOUT 36 HOURS WITH CONTINUED STRENGTHENING TO GREATER THAN 90 KT IN LESS THAN 72 HOURS... WHILE SHIPS SHOWS STEADY BUT MORE CONSERVATIVE STRENGTHENING. THE OFFICIAL FORECAST IS IN BETWEEN AND IS SIMILAR TO THE PREVIOUS ADVISORY. FORECASTER KNABB FORECAST POSITIONS AND MAX WINDS INITIAL 16/0300Z 17.0N 79.0W 25 KT 12HR VT 16/1200Z 16.8N 79.5W 35 KT 24HR VT 17/0000Z 16.6N 80.0W 45 KT 36HR VT 17/1200Z 16.6N 80.4W 55 KT 48HR VT 18/0000Z 16.8N 80.8W 65 KT 72HR VT 19/0000Z 17.5N 81.5W 75 KT 96HR VT 20/0000Z 18.5N 82.5W 85 KT 120HR VT 21/0000Z 20.5N 83.0W 85 KT |
