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| #90711 (Received by flhurricane at: 5:03 PM 10.Jun.2006) TCDAT1 TROPICAL DEPRESSION ONE DISCUSSION NUMBER 3 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL012006 500 PM EDT SAT JUN 10 2006 THE DEPRESSION IS STRUGGLING TO MAINTAIN A SINGLE COHERENT SURFACE CIRCULATION. A SERIES OF SMALL VORTICES HAVE ALL DAY BEEN ROTATING ABOUT THE MEAN CENTER OF THE BROADER CIRCULATION THAT IS EXTREMELY ELONGATED SOUTHWEST TO NORTHEAST. EVEN GIVEN DATA FROM THE AIR FORCE RECONNAISSANCE PLANE THAT IS STILL INVESTIGATING THE SYSTEM... WHERE TO SPECIFY A CIRCULATION CENTER IS VERY CHALLENGING. RECON FOUND A WIND SHIFT AND A BROAD PRESSURE MINIMUM IN THE YUCATAN CHANNEL AT ABOUT 18Z... BUT THAT DID NOT QUALIFY AS A WELL-DEFINED CENTER OF A VORTEX. THE AIRCRAFT IS INVESTIGATING OTHER PORTIONS OF THE CIRCULATION TO HELP DETERMINE WHERE THE CENTER IS LOCATED. FOR NOW I HAVE PLACED THE ADVISORY POSITION AT ABOUT THE CENTROID OF THE BROAD CLOUD CIRCULATION SEEN IN SATELLITE IMAGERY... WHICH RESULTS IN A NET MOTION OF ABOUT 5 KT TOWARD THE NORTH-NORTHWEST DURING THE PAST FEW HOURS. IN THE BIGGER PICTURE... MOST OF THE CONVECTION REMAINS TO THE EAST OF THE ELONGATED CENTER. IN ADDITION TO THE INTERNAL DISORGANIZATION... THE DEPRESSION IS BATTLING SOUTHWESTERLY WIND SHEAR IN BETWEEN A MID- TO UPPER-LEVEL TROUGH OVER THE SOUTHWESTERN GULF OF MEXICO AND AN UPPER-LEVEL ANTICYCLONE OVER THE WESTERN CARIBBEAN... AND DRY AIR OVER THE GULF THAT IMPINGING ON WESTERN SIDE OF THE CYCLONE. SURFACE OBSERVATIONS AND THE AIRCRAFT DATA SUGGEST 30 KT REMAINS A GOOD INITIAL INTENSITY ESTIMATE. THE TRACK AND INTENSITY FORECAST ARE BOTH HIGHLY UNCERTAIN... DUE TO THE CURRENT STATE OF THE SYSTEM AND SINCE THE SYSTEM WILL REMAIN IN A SHEARED ENVIRONMENT THROUGHOUT ITS STAY IN THE GULF OF MEXICO. WHILE THE DYNAMICAL MODELS ARE IN FAIRLY GOOD AGREEMENT THAT THE CENTER OF THE CYCLONE WILL TURN NORTHEASTWARD OVER THE EASTERN GULF OF MEXICO AND CROSS THE NORTHERN PORTIONS OF FLORIDA... THEY DISAGREE GREATLY ON THE TIMING. THE NEW OFFICIAL FORECAST IS SLOWER THAN BUT OTHERWISE SIMILAR TO THE PREVIOUS ADVISORY TO BE CLOSER TO THE MODEL CONSENSUS... OR BASICALLY AN AVERAGE OF THE VARIOUS MODEL SOLUTIONS. THE OFFICIAL INTENSITY FORECAST PEAKS AT 45 KT OVER THE GULF... LESS THAN IN PREVIOUS ADVISORIES... TO ACCOUNT FOR THE CURRENT POOR ORGANIZATION AND EXPECTED INCREASE IN VERTICAL SHEAR OVER THE NORTHEASTERN GULF. EXTRATROPICAL TRANSITION IS STILL EXPECTED AS THE SYSTEM MOVES NORTHEASTWARD NEAR THE EAST COAST OF THE UNITED STATES AHEAD OF A MID-LATITUDE TROUGH. FORECASTER KNABB FORECAST POSITIONS AND MAX WINDS INITIAL 10/2100Z 21.8N 85.7W 30 KT 12HR VT 11/0600Z 23.2N 86.3W 35 KT 24HR VT 11/1800Z 25.0N 86.5W 40 KT 36HR VT 12/0600Z 26.5N 86.0W 45 KT 48HR VT 12/1800Z 28.1N 84.1W 45 KT 72HR VT 13/1800Z 31.5N 79.5W 40 KT...BECOMING EXTRATROPICAL 96HR VT 14/1800Z 37.5N 71.5W 40 KT...EXTRATROPICAL 120HR VT 15/1800Z 47.5N 60.0W 40 KT...EXTRATROPICAL |
