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#38359 (Received by flhurricane at: 11:03 AM 08.Aug.2005) TCDAT4 TROPICAL DEPRESSION IRENE DISCUSSION NUMBER 16 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 AM EDT MON AUG 08 2005 THE EXPOSED LOW-LEVEL CIRCULATION HAS BECOME INCREASINGLY SEPARATED FROM WHAT IS LEFT OF THE CONVECTION TO ITS EAST THAT OCCURRED OVERNIGHT. A QUIKSCAT OVERPASS NEAR 0820Z MISSED MOST OF THE CIRCULATION BUT DID INDICATE SOME 35 KT WINDS JUST OUTSIDE OF THE DEEP CONVECTION IN THE NORTHEASTERN QUADRANT. HOWEVER... AT THAT TIME THE CONVECTION WAS DEEPER AND MORE INVOLVED WITH THE LOW-LEVEL CENTER THAN IT HAS BEEN DURING THE PAST COUPLE OF HOURS... SO IT IS PROBABLY SAFE TO ASSUME THAT THE WINDS HAVE DECREASED SINCE THEN. DVORAK INTENSITY ESTIMATES HAVE ALSO FALLEN TO 30 KT. IRENE IS THEREFORE DOWNGRADED TO A TROPICAL DEPRESSION WITH 30 KT WINDS. A LIMITED AMOUNT OF CONVECTION HAS RESUMED JUST EAST OF THE CENTER...BUT IT REMAINS TO BE SEEN IF THIS IS THE START OF A COMEBACK. THE INTENSITY FORECAST IS ADJUSTED DOWNWARD FROM THE PREVIOUS ADVISORY...AND CLOSER TO THE GFDL THAN THE SHIPS GUIDANCE. THE TRACK AND INTENSITY FORECASTS ARE ALWAYS INTERDEPENDENT TO SOME DEGREE...BUT FOR IRENE...ESPECIALLY IN THE 3-5 DAY PERIOD...ONE COULD AFFECT THE OTHER PERHAPS MORE SO THAN USUAL. THE INITIAL MOTION ESTIMATE IS 285/14. BASED ON A IRENE REMAINING WEAKER THAN PREVIOUSLY EXPECTED...A CONTINUED WEST-NORTHWESTWARD MOTION WITHIN THE LOW TO MID LEVEL FLOW IS FORECAST UNTIL VERY LATE IN THE FORECAST...WHICH WOULD TAKE THE SYSTEM FARTHER WEST THAN THE PREVIOUS ADVISORY. THIS SCENARIO IS IN BEST AGREEMENT WITH THE GFDL...ECMWF...AND BAM SHALLOW SOLUTIONS. FORECASTER KNABB FORECAST POSITIONS AND MAX WINDS INITIAL 08/1500Z 22.4N 50.7W 30 KT 12HR VT 09/0000Z 22.9N 52.1W 30 KT 24HR VT 09/1200Z 23.5N 54.3W 30 KT 36HR VT 10/0000Z 24.0N 56.5W 35 KT 48HR VT 10/1200Z 24.6N 58.8W 40 KT 72HR VT 11/1200Z 26.5N 63.0W 40 KT 96HR VT 12/1200Z 29.0N 66.5W 45 KT 120HR VT 13/1200Z 31.0N 67.0W 45 KT |