Tropical Depression SIX-E
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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
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