ZCZC MIATCDAT4 ALL TTAA00 KNHC DDHHMM TROPICAL STORM CLAUDETTE DISCUSSION NUMBER 4 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 AM EDT WED JUL 09 2003 CLAUDETTE HAS WEAKENED SOME THIS MORNING. SOUTHWESTERLY VERTICAL SHEAR HAS CAUSED THE CENTER TO BECOME INTERMITTENTLY EXPOSED ON THE EDGE OF THE CONVECTION...AND A RECONNAISSANCE AIRCRAFT INDICATES A CENTRAL PRESSURE OF 1004 MB ALONG WITH FLIGHT-LEVEL WINDS OF 59 KT. BASED ON THIS THE MAXIMUM WINDS ARE REDUCED TO 55 KT...AND THIS MAY BE A LITTLE GENEROUS. THE INITIAL MOTION IS 275/21. THERE IS LITTLE CHANGE IN THE SYNOPTIC PATTERN AND THE FORECAST PHILOSOPHY FROM THE PREVIOUS PACKAGE. CLAUDETTE REMAINS SOUTH OF A DEEP LAYER SUBTROPICAL RIDGE...WHOSE WESTERN END IS FORECAST TO WEAKEN AFTER 36 HR AS A DEEP-LAYER TROUGH DEVELOPS OVER THE EASTERN UNITED STATES. CLAUDETTE WILL LIKELY BE TOO FAR SOUTH AND WEST TO RECURVE AHEAD OF THE TROUGH...SO THE MOST LIKELY RESPONSE OF THE STORM IS A SLOW MOTION WHILE OVER THE GULF OF MEXICO. THE TRACK FORECAST CALLS FOR A GRADUALLY DECELERATING WEST-NORTHWESTWARD MOTION THROUGH 36-48 HR AS CLAUDETTE APPROACHES THE WESTERN END OF THE RIDGE...FOLLOWED BY A SLOWER NORTHWESTWARD MOTION OVER THE GULF OF MEXICO. THIS TRACK FORECAST IS ALONG THE SOUTHERN EDGE OF THE DYNAMICAL MODELS. IT SHOULD BE NOTED THAT BAMS AND NHC98 ARE SOUTH OF THE CURRENT FORECAST...BUT COULD VERIFY IF CLAUDETTE WEAKENS FURTHER. AIRCRAFT DATA SHOWS THAT THE CLAUDETTE VORTEX IS RATHER SMALL...SO THERE IS A DISTINCT POSSIBILITY THAT IF THE SHEAR PERSISTS THE SYSTEM COULD WEAKEN TO AN EASTERLY WAVE. ASSUMING THAT DOES NOT HAPPEN...LARGE-SCALE MODELS FORECAST THE UPPER-LEVEL LOW WEST OF CLAUDETTE TO WEAKEN AFTER 12-24 HR AND THE SHEAR TO DECREASE. THE LOW APPEARS STRONGER ON WATER VAPOR IMAGERY THAN ANY OF THE MODEL FORECASTS FOR 12Z...SO IT WILL LIKELY HANG ON LONGER THAN THE MODELS CURRENTLY FORECAST. BASED ON THIS...THE INTENSITY FORECAST WILL CALL FOR CLAUDETTE TO CHANGE LITTLE FOR THE NEXT 24 HR IN A MARGINAL AT BEST ENVIRONMENT...FOLLOWED BY STRENGTHENING AS THE CYCLONE APPROACHES YUCATAN. BY THE TIME CLAUDETTE REACHES THE GULF OF MEXICO...A LARGE-SCALE UPPER-LEVEL ANTICYCLONE SHOULD BE IN PLACE TO PROVIDE A FAVORABLE ENVIRONMENT. FORECASTER BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 09/1500Z 15.5N 77.6W 55 KT 12HR VT 10/0000Z 16.3N 80.5W 55 KT 24HR VT 10/1200Z 17.6N 83.8W 55 KT 36HR VT 11/0000Z 19.1N 86.7W 60 KT 48HR VT 11/1200Z 20.5N 89.0W 40 KT...INLAND 72HR VT 12/1200Z 22.5N 91.5W 45 KT...OVER WATER 96HR VT 13/1200Z 24.0N 93.0W 50 KT 120HR VT 14/1200Z 25.5N 94.0W 60 KT NNNN
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Page last modified: Monday, 07-Feb-2005 16:49:56 UTC