ZCZC MIATCDEP1 ALL TTAA00 KNHC DDHHMM TROPICAL DEPRESSION TWENTY-ONE-E SPECIAL DISCUSSION NUMBER 1 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP212006 1000 PM PDT MON NOV 13 2006 OVER THE PAST COUPLE OF HOURS...DEEP CONVECTION HAS INCREASED NEAR THE ESTIMATED CENTER OF THE LOW PRESSURE SYSTEM SEVERAL HUNDRED MILES SOUTH OF MANZANILLO MEXICO AND BANDING FEATURES ARE STARTING TO BECOME MORE EVIDENT. THEREFORE THE SYSTEM IS BEING DESIGNATED AS A TROPICAL CYCLONE AND A SPECIAL ADVISORY IS BEING ISSUED AT THIS TIME. VERTICAL SHEAR IS CURRENTLY LIGHT OVER THE AREA AND GRADUAL STRENGTHENING IS LIKELY OVER THE NEXT DAY OR TWO. THEREAFTER...WE EXPECT THE SYSTEM TO COME UNDER THE INFLUENCE OF STRONG WEST-SOUTHWESTERLY UPPER-LEVEL WINDS WHICH WOULD REVERSE THE INTENSIFICATION PROCESS. THE NHC WIND SPEED FORECAST IS BELOW THE SHIPS GUIDANCE SINCE WE DO NOT BELIEVE THAT MODEL IS DIAGNOSING STRONG ENOUGH SHEAR IN THE LATTER PART OF THE FORECAST PERIOD. INITIAL MOTION IS ABOUT 300/7. STEERING CURRENTS ARE FORECAST TO COLLAPSE AS HIGH PRESSURE WEAKENS TO THE NORTH OF THE TROPICAL CYCLONE. GLOBAL MODELS SUCH AS THE GFS APPEAR TO HAVE BOTH A POOR INITIALIZATION AND AN UNREALISTIC EVOLUTION OF THE SYSTEM AS THEY SEEM TO OVEREMPHASIZE A CYCLONIC CIRCULATION TO THE WEST AND SOUTHWEST OF THE TROPICAL CYCLONE. AT THE MOMENT...THE COURSE OF LEAST REGRET IS TO FORECAST A SLOW...AND GENERALLY NORTHWESTWARD... MOTION THROUGH MOST OF THE FORECAST PERIOD. FORECAST POSITIONS AND MAX WINDS INITIAL 14/0500Z 12.9N 104.5W 25 KT 12HR VT 14/1200Z 13.4N 105.2W 35 KT 24HR VT 15/0000Z 14.0N 105.8W 40 KT 36HR VT 15/1200Z 14.5N 106.2W 45 KT 48HR VT 16/0000Z 15.0N 106.6W 45 KT 72HR VT 17/0000Z 16.0N 107.0W 40 KT 96HR VT 18/0000Z 17.0N 107.5W 35 KT 120HR VT 19/0000Z 17.5N 108.0W 30 KT $$ FORECASTER PASCH/BROWN NNNN
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Page last modified: Tuesday, 14-Nov-2006 05:54:46 UTC