ZCZC MIATCDEP5 ALL TTAA00 KNHC DDHHMM TROPICAL DEPRESSION FIFTEEN-E DISCUSSION NUMBER 3 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2 PM PDT WED SEP 28 2005 TROPICAL DEPRESSION 15-E REMAINS A WELL-ORGANIZED TROPICAL CYCLONE IN TERMS OF THE LOW-LEVEL WIND FIELD... AS NOTED IN 28/1302Z QUIKSCAT WIND DATA. EVEN THOUGH THE DEPTH AND AMOUNT OF CONVECTION HAS DECREASED SHARPLY SINCE THIS MORNING... THERE REMAINS A SIGNIFICANT CONVECTIVE BAND WRAPPING AROUND THE CENTER IN THE NORTHWEST SEMICIRCLE. THE ADVISORY INTENSITY OF 30 KT IS BASED ON A CONSENSUS DVORAK SATELLITE INTENSITY ESTIMATE OF T2.0/30 KT FROM ALL THREE SATELLITE AGENCIES. UPPER-LEVEL REMAINS FAIR TO GOOD IN ALL QUADRANTS... EXCEPT TO THE NORTHEAST DUE TO UPPER-LEVEL SHEAR. THE INITIAL MOTION ESTIMATE REMAINS 270/06. THE LOW-LEVEL CENTER IS A LITTLE DIFFICULT TO ASCERTAIN AS A COUPLE OF SMALL VORTICES HAVE BEEN NOTED ROTATING CYCLONICALLY AROUND THE SOUTHERN AND EASTERN QUADRANTS THIS AFTERNOON. THE LAST FEW IMAGES... HOWEVER... SUGGEST THAT THE DOMINANT CIRCULATION CENTER HAS PULLED UNDERNEATH THE WELL-DEFINED MID-LEVEL CENTER... AND THAT WAS THE FEATURE USED TO LOCATE THE CENTER OF TD-15E FOR THIS ADVISORY. THE BROAD EAST-WEST ORIENTED SUBTROPICAL RIDGE LOCATED ACROSS TEXAS AND NORTHERN MEXICO IS FORECAST TO REMAIN INTACT THROUGH ABOUT THE NEXT 48 HOURS... WHICH SHOULD ACT TO KEEP TD-15E MOVING IN A WEST-NORTHWESTWARD DIRECTION. AFTERWARDS... ALL OF THE GLOBAL MODELS AND THE GFDL MODEL ARE IN GOOD AGREEMENT ON A MID-LEVEL SHORTWAVE TROUGH TO DIG SOUTHWARD FROM THE FAR NORTH PACIFIC AND ERODE THE WESTERN PORTION OF THE RIDGE. AN ELONGATED MID-LEVEL TROUGH OR A CLOSED LOW IS FORECAST TO PERSIST OFF THE CALIFORNIA COAST IN 72 TO 120 HOURS... WHICH IS EXPECTED TO TURN THE CYCLONE MORE NORTHWARD AND POSSIBLY RESULT IN LANDFALL ALONG THE WEST COAST OF BAJA CALIFORNIA IN 96-120 HOURS. THE MAIN DIFFERENCE BETWEEN THE MODELS REMAINS THE TIMING AND DEGREE OF EROSION OF THE RIDGE. THE GFDL MODEL ROCKETS THE CYCLONE NORTHWARD AND HAS IT OVER SOUTHERN UTAH IN 120 HOURS. THIS IS CLEARLY THE OUTLIER MODEL AT THIS TIME SINCE THE REMAINDER OF THE MODEL GUIDANCE IS MUCH SLOWER AND KEEPS THE CYCLONE OVER OR SOUTHWEST OF BAJA CALIFORNIA THROUGHOUT THE FORECAST PERIOD. SINCE THE GLOBAL MODELS INITIALIZED TD-15E QUITE WELL AT 12Z... THE OFFICIAL TRACK IS CLOSE TO THE NHC MODEL CONSENSUS... ONLY SLOWER DUE TO CONTAMINATION CAUSED BY THE MUCH FASTER GFDL MODEL. THE VERTICAL SHEAR IS GRADUALLY DECREASING AND IS NOW ABOUT 15 KT FROM THE NORTHEAST. BY 48 HOURS... THE SHEAR IS STILL FORECAST TO DECREASE TO 5 KT OR LESS WHILE THE CYCLONE IS OVER 28-29C SSTS. AS A RESULT... INTENSIFICATION TO HURRICANE STRENGTH IS FORECAST... WHICH REMAINS HIGHER THAN THE SHIPS INTENSITY MODEL... BUT SIMILAR TO THE GFDL MODEL. BY DAYS 4 AND 5... THE CYCLONE IS FORECAST TO MOVE OVER MUCH COOLER WATER AND GRADUALLY WEAKEN. HOWEVER... DUE TO THE SHARP SST-GRADIENT THAT EXISTS WITHIN 100 NMI OF THE WEST COAST OF BAJA CALFIFORNIA... JUST A SLIGHT DEVIATION RIGHT/LEFT OF TRACK COULD RESULT IN A SIGNIFICANTLY HIGHER/LOWER INTENSITY AT 72 HOURS THROUGH 120 HOURS. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 28/2100Z 17.1N 106.6W 30 KT 12HR VT 29/0600Z 17.6N 107.7W 35 KT 24HR VT 29/1800Z 18.3N 109.1W 40 KT 36HR VT 30/0600Z 19.2N 110.5W 45 KT 48HR VT 30/1800Z 20.1N 111.5W 55 KT 72HR VT 01/1800Z 21.7N 112.9W 65 KT 96HR VT 02/1800Z 23.5N 114.0W 55 KT 120HR VT 03/1800Z 26.0N 114.5W 45 KT $$ NNNN
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Page last modified: Wednesday, 28-Sep-2005 20:25:23 UTC