ZCZC MIATCDEP2 ALL TTAA00 KNHC DDHHMM TROPICAL DEPRESSION GREG DISCUSSION NUMBER 18 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 8 AM PDT MON AUG 15 2005 GOES SHORTWAVE INFRARED IMAGERY CONTINUES TO REVEAL AN EXPOSED LOW- LEVEL CIRCULATION WITH THE NEAREST CONVECTION ABOUT 40-45 NM SOUTHWEST OF THE LOW LEVEL CENTER. EASTERLY SHEAR MAINTAINS ITS GRIP ON THE SYSTEM. DVORAK INTENSITY ESTIMATES REMAIN 30 KT...AS DOES THE ADVISORY INTENSITY. DUE TO THE CURRENT DISORGANIZATION OF THE DEPRESSION...AND SINCE THE SHEAR IS NOT FORECAST TO RELAX...NO INTENSITY CHANGE IS INDICATED...DESPITE THE AGGRESSIVE GFDL AND OPTIMISTIC SHIPS FORECASTS. THE MOTION OVER THE PAST 6 HOURS HAS OSCILLATED BETWEEN SOUTHWEST AND WEST-SOUTHWEST WITH A MEAN INITIAL MOTION OF 245/4. THE FORECAST SOLUTIONS FROM THE VARIOUS DYNAMICAL MODELS ARE IN BETTER AGREEMENT AT LEAST THROUGH 72 HOURS AND ARE UNANIMOUS IN FORECASTING A GENERAL WESTWARD TREND. THE MODELS DIVERGE SIGNIFICANTLY AFTER 72 HOURS WITH THE NOGAPS/UKMET AND THE GUNS...GUNA AND CONU DYNAMICAL CONCENSUS FORECASTING A TURN TOWARD THE NORTHWEST. ONCE AGAIN THE GFDL FORECASTS A SLOW WEST- SOUTHWESTWARD DRIFT AS A STRENGTHENING TROPICAL STORM FOR THE NEXT THREE DAYS...FOLLOWED BY AN ABRUPT TURN TO THE NORTH-NORTHEAST. THE GFS IS FORECASTING A FAIRLY SIGNIFICANT MID LEVEL CIRCULATION SOUTH OF BAJA CALIFORNIA...WHICH IS LIKELY DUE TO POOR INITIALIZATION. THEREFORE THAT MODEL'S TRACK...WHICH MOVES GREG IN A CLOCKWISE LOOP...DOES NOT APPEAR TO BE REALISTIC. THE OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS AND INDICATES A VERY SLOW WESTWARD MOTION AT ABOUT 5 KNOTS THROUGHOUT THE FORECAST PERIOD. FORECASTER COBB/PASCH FORECAST POSITIONS AND MAX WINDS INITIAL 15/1500Z 14.0N 116.4W 30 KT 12HR VT 16/0000Z 13.7N 117.0W 30 KT 24HR VT 16/1200Z 13.4N 117.7W 30 KT 36HR VT 17/0000Z 13.1N 118.6W 30 KT 48HR VT 17/1200Z 12.7N 120.0W 30 KT 72HR VT 18/1200Z 12.5N 122.0W 30 KT 96HR VT 19/1200Z 12.5N 124.0W 30 KT 120HR VT 20/1200Z 12.5N 126.0W 30 KT $$ NNNN
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Page last modified: Monday, 15-Aug-2005 14:55:11 UTC