ZCZC MIATCDAT5 ALL TTAA00 KNHC DDHHMM TROPICAL STORM DANNY DISCUSSION NUMBER 10 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL052009 500 PM EDT FRI AUG 28 2009 AFTER STALLING EARLIER THIS AFTERNOON...THE CENTER OF DANNY IS FINALLY MOVING SLOWLY NORTHWARD OR NORTH-NORTHEASTWARD. DATA FROM AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT SUGGEST THAT DANNY IS STILL A MINIMAL TROPICAL STORM...BASED ON A 33-KT OBSERVATION FROM THE SFMR IN THE SOUTHEASTERN QUADRANT. THE INTENSITY FORECAST SHOWS THE POSSIBILITY FOR A LITTLE STRENGTHENING IN THE SHORT TERM...AS THE INCREASING UPPER-LEVEL DIVERGENCE COULD SUPPORT THE REDEVELOPMENT OF CONVECTION NEAR THE CENTER. HOWEVER...BY 24 HOURS...DANNY WILL BE MOVING INTO A VERY UNFAVORABLE ENVIRONMENT FOR A TROPICAL CYCLONE...WITH THE SHIPS MODEL SHOWING WIND SHEAR INCREASING TO 35 KT BY THAT TIME. BY 36 HOURS...DANNY WILL BE OVER SSTS OF NEAR 20C...AND INTERACTING WITH THE DEEP-LAYER BAROCLINIC TROUGH OVER THE EASTERN U.S. MOST OF THE LATEST GLOBAL MODELS AND PHASE SPACE DIAGRAMS SHOW THAT DANNY WILL BE EXTRATROPICAL BY THAT TIME. THERE IS THE POTENTIAL FOR SOME INTENSIFICATION OF DANNY LATE IN THE FORECAST PERIOD AS AN EXTRATROPICAL CYCLONE OVER THE NORTH ATLANTIC. THE GUIDANCE WAS INITIALIZED WITH A LONG TERM MOTION OF 315/08... AND REMAINS IS GOOD AGREEMENT ON THE RAPID ACCELERATION OF DANNY NORTHWARD AND NORTH-NORTHEASTWARD. IN FACT...THE MODEL SPREAD IS SMALLER NOW THAN IT WAS EARLIER TODAY. THE OFFICIAL TRACK IS SLOWER THAN THE MODEL CONSENSUS THROUGH MOST OF THE PERIOD DUE TO THE SLOW INITIAL MOTION. FROM 24 TO 36 HOURS...THE NEW FORECAST IS SHIFTED TO THE RIGHT OF THE PREVIOUS FORECAST TRACK...BUT DANNY IS STILL EXPECTED TO MOVE CLOSE TO THE SOUTHEASTERN COAST OF NEW ENGLAND AND APPROACH NOVA SCOTIA IN 36-48 HOURS. DATA FROM THE AIRCRAFT SUGGEST THAT THE ONLY 34-KT WINDS ARE LOCATED IN THE SOUTHEASTERN QUADRANT. THE LACK OF WINDS ON THE WEST SIDE OF DANNY LESSEN THE THREAT FOR TROPICAL STORM WIND REACHING THE NORTH CAROLINA OUTER BANKS. HOWEVER...THE WATCH IS LEFT IN PLACE IN CASE THE WIND FIELD BECOMES BETTER DEFINED ON THE WESTERN SIDE OF DANNY. AS DANNY BECOMES EXTRATROPICAL...ITS EXPANDING WIND FIELD MAY IMPACT THE COAST OF NEW ENGLAND. THESE POTENTIAL IMPACTS WILL BE HANDLED WITH GALE WARNINGS AND OTHER PRODUCTS ISSUED BY LOCAL NWS OFFICES IN THAT REGION. FORECAST POSITIONS AND MAX WINDS INITIAL 28/2100Z 30.4N 75.4W 35 KT 12HR VT 29/0600Z 32.7N 75.8W 40 KT 24HR VT 29/1800Z 37.3N 73.2W 40 KT 36HR VT 30/0600Z 41.9N 68.2W 40 KT...EXTRATROPICAL 48HR VT 30/1800Z 46.5N 61.4W 40 KT...EXTRATROPICAL 72HR VT 31/1800Z 50.5N 49.5W 40 KT...EXTRATROPICAL 96HR VT 01/1800Z 53.0N 35.0W 45 KT...EXTRATROPICAL 120HR VT 02/1800Z 55.0N 22.0W 50 KT...EXTRATROPICAL $$ FORECASTER BRENNAN NNNN
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Page last modified: Thursday, 31-Dec-2009 12:09:08 UTC