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#113287 (Received by flhurricane at: 11:11 PM 27.Sep.2006) TCDAT4 TROPICAL DEPRESSION NINE DISCUSSION NUMBER 2 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092006 1100 PM EDT WED SEP 27 2006 ALTHOUGH THE DEPRESSION IS NOT VERY IMPRESSIVE IN CONVENTIONAL SATELLITE IMAGERY... MICROWAVE OVERPASSES BY QUIKSCAT AT 2132 UTC AND SSMIS AT 2309 UTC SUGGEST THAT IT IS NEARING TROPICAL STORM STRENGTH. LATEST DVORAK INTENSITY ESTIMATES...HOWEVER...REMAIN 30 KT FROM ALL AGENCIES AND THIS WILL BE THE ADVISORY INTENSITY. THE CENTER OF THE DEPRESSION IS LOCATED JUST SOUTH OF THE PRIMARY AREA OF DEEP CONVECTION DUE TO SOUTHERLY WIND SHEAR IMPOSED BY AN UPPER-LEVEL LOW TO THE WEST OF THE DEPRESSION. MOST OF THE GLOBAL MODELS GRADUALLY WEAKEN THIS FEATURE AND THEREFORE THE SHEAR OVER THE NEXT DAY OR TWO. THE OFFICIAL FORECAST CALLS FOR GRADUAL STRENGTHENING DURING THE NEXT 48 HOURS. THEREAFTER...SOUTHWESTERLY SHEAR IS EXPECTED TO INCREASE AGAIN WHILE SSTS COOL...WHICH SHOULD INHIBIT FURTHER STRENGTHENING. THE NEW OFFICIAL INTENSITY FORECAST IS CLOSE TO THE SHIPS AND GFDL INTENSITY GUIDANCE...AND SIMILAR TO THE PREVIOUS ADVISORY. THE INITIAL MOTION ESTIMATE IS 315/11. GLOBAL MODEL GUIDANCE INDICATES THAT THE DEPRESSION WILL BE STEERED AROUND THE WESTERN PERIPHERY OF A MID-TROPOSPHERIC RIDGE LOCATED TO THE NORTHEAST OF THE CYCLONE. IN ABOUT 48 HOURS...A LARGE DEEP LAYERED TROUGH IS PREDICTED TO BE DEPARTING THE EAST COAST OF THE UNITED STATES. THIS SHOULD ALLOW THE TROPICAL CYCLONE TO TURN NORTHWARD...THEN NORTHEASTWARD AHEAD OF THIS TROUGH. THE GFS IS ON THE WESTERN EDGE OF THE MODEL GUIDANCE AS IT DEPICTS A MUCH WEAKER AND MORE SHALLOW SYSTEM THAN ANTICIPATED BY THE SHIPS AND GFDL. SINCE THE SHIPS AND GFDL ARE IN SUCH GOOD AGREEMENT ON THE FUTURE INTENSITY OF THE SYSTEM...THE GFDL TRACK MIGHT BE A MORE LIKELY SOLUTION. THE OFFICIAL FORECAST IS ADJUSTED WESTWARD AND SLOWER COMPARED TO THE PREVIOUS ADVISORY TO BE IN BETTER AGREEMENT WITH THE GFDL TRACK. INITIAL 28/0300Z 27.2N 53.8W 30 KT 12HR VT 28/1200Z 28.2N 55.0W 35 KT 24HR VT 29/0000Z 29.9N 56.5W 40 KT 36HR VT 29/1200Z 31.6N 57.6W 45 KT 48HR VT 30/0000Z 33.6N 58.1W 50 KT 72HR VT 01/0000Z 38.0N 57.0W 50 KT 96HR VT 02/0000Z 42.0N 52.5W 50 KT...EXTRATROPICAL 120HR VT 03/0000Z 46.0N 45.0W 50 KT...EXTRATROPICAL $$ FORECASTER BROWN/KNABB |