ZCZC MIATCDEP1 ALL TTAA00 KNHC DDHHMM TROPICAL DEPRESSION SIX-E DISCUSSION NUMBER 1 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 8 PM PDT THU JUL 17 2003 MICROWAVE DATA SUGGEST THAT THE TROPICAL DISTURBANCE SOUTHWEST OF MANZANILLO HAS A LOW-LEVEL CIRCULATION SOMEWHAT DISPLACED TO THE EAST OF THE MAIN CONVECTION. BASED ON THIS...AND DVORAK CLASSIFICATIONS THAT WERE A CONSENSUS 2.0 FROM THE THREE AGENCIES...THE DISTURBANCE IS UPGRADED TO A TROPICAL DEPRESSION. THE DEPRESSION IS NOT WELL ORGANIZED AT THIS TIME AND THERE IS SUBSTANTIAL EASTERLY SHEAR. THE GLOBAL MODELS SUGGEST THAT THE SHEAR WILL GRADUALLY LESSEN...ALTHOUGH I DO NOT SEE WHY THE SHIPS MODEL READS THE SHEAR AS LESSENING TO ABOUT 5 KT IN 48 HOURS. WITH THIS...THE SHIPS MODEL BRINGS THE DEPRESSION TO HURRICANE STRENGTH IN 72 HOURS OVER 26C WATERS. THIS SEEMS EXCESSIVE TO ME...PARTICULARLY GIVEN THE POOR INITIAL ORGANIZATION AND LACK OF DEVELOPMENT SHOWN EXPLICITLY IN THE GLOBAL MODELS. THE INITIAL MOTION IS 285/13...BUT VERY UNCERTAIN. THE DEPRESSION IS SOUTH OF A MID-LEVEL RIDGE CENTERED OVER THE SOUTHERN ROCKIES. IN TWO TO THREE DAYS...THE CYCLONE WILL BE NEARING A WEAKNESS IN THIS RIDGE AND SO THE FORWARD MOTION SHOULD SLOW SOME AT THAT TIME. THE OFFICIAL FORECAST IS BASED LARGELY ON THE GFS AND BAMM GUIDANCE. FORECASTER FRANKLIN FORECAST POSITIONS AND MAX WINDS INITIAL 18/0300Z 14.6N 107.4W 30 KT 12HR VT 18/1200Z 15.0N 109.3W 30 KT 24HR VT 19/0000Z 15.2N 112.3W 35 KT 36HR VT 19/1200Z 15.5N 115.6W 40 KT 48HR VT 20/0000Z 15.5N 119.0W 45 KT 72HR VT 21/0000Z 16.5N 123.5W 45 KT 96HR VT 22/0000Z 17.5N 128.0W 40 KT 120HR VT 23/0000Z 18.0N 133.5W 30 KT NNNN
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Page last modified: Monday, 07-Feb-2005 16:49:56 UTC