ZCZC MIATCDAT3 ALL TTAA00 KNHC DDHHMM TROPICAL DEPRESSION EIGHT DISCUSSION NUMBER 1 NATIONAL WEATHER SERVICE MIAMI FL 5 PM EDT TUE SEP 11 2001 SURFACE DATA SHOW A DEFINITE CLOSED CYCLONIC CIRCULATION OVER THE SOUTHEAST GULF OF MEXICO. DEEP CONVECTION DOES NOT SHOW MUCH CURVATURE...BUT IT IS DEEMED SUFFICIENTLY ORGANIZED NEAR THE LOW PRESSURE CENTER TO WARRANT CLASSIFYING THE SYSTEM AS A TROPICAL DEPRESSION. THERE IS NORTHERLY SHEAR OVER THE AREA...AND WATER VAPOR ANIMATION SHOWS AN UPPER-LEVEL CYCLONIC VORTICITY MAXIMUM MOVING SOUTH-SOUTHEASTWARD FROM THE NORTHEAST GULF COAST...TOWARD THE DEPRESSION. THIS COULD INHIBIT STRENGTHENING FOR A WHILE...SO THE INTENSITY FORECAST SHOWS LITTLE CHANGE FOR THE NEXT DAY OR SO. LATER IN THE PERIOD...THERE IS SOME DIFFERENCE OF OPINION AMONG THE GLOBAL MODELS AS TO HOW FAVORABLE THE UPPER-LEVEL ENVIRONMENT WILL BECOME. THE U.K. MET OFFICE MODEL SHOWS A DIFFLUENT...FAIRLY LIGHT WIND REGIME AT 200 MB OVER THE EASTERN GULF IN 2-3 DAYS...WHEREAS THE AVN MODEL SHOWS AN UPPER-LEVEL TROUGH OVER THE NORTHERN HALF OF THE GULF. THE FORMER REGIME COULD LEAD TO A SIGNIFICANT TROPICAL CYCLONE...WHEREAS THE LATTER FAVORS A MORE BAROCLINIC-TYPE DEVELOPMENT. THE DEPRESSION HAS BEEN DRIFTING TOWARD THE WEST-SOUTHWEST...AND STEERING CURRENTS ARE EXPECTED TO BE RATHER WEAK OVER THE EASTERN GULF FOR THE NEXT DAY OR TWO. THE AVN MODEL INDICATES THAT THE UPPER-LEVEL TROUGH WILL CARRY THE CYCLONE TOWARD AND OVER THE CENTRAL FLORIDA PENINSULA. ON THE OTHER HAND...THE NOGAPS MODEL INDICATES THAT THE SYSTEM WILL BE STEERED SLOWLY WEST-SOUTHWESTWARD ON THE SOUTHEAST FLANK OF A MID-LEVEL RIDGE OVER THE NORTHWEST GULF. THE U.K. MET OFFICE IS MORE OR LESS IN BETWEEN THESE OPTIONS...AND SHOWS LITTLE MOTION OVER THE NEXT 3 DAYS. THE OFFICIAL FORECAST IS A COMPROMISE OF THESE POSSIBILITIES. FORECASTER PASCH FORECAST POSITIONS AND MAX WINDS INITIAL 11/2100Z 25.5N 84.2W 25 KTS 12HR VT 12/0600Z 25.4N 84.6W 30 KTS 24HR VT 12/1800Z 25.4N 85.2W 30 KTS 36HR VT 13/0600Z 26.0N 85.5W 35 KTS 48HR VT 13/1800Z 26.5N 85.5W 40 KTS 72HR VT 14/1800Z 28.0N 84.0W 50 KTS NNNN