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| #148862 (Received by flhurricane at: 11:05 PM 31.Aug.2007) TCDAT1 TROPICAL DEPRESSION SIX DISCUSSION NUMBER 2 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL062007 1100 PM EDT FRI AUG 31 2007 REPORTS FROM AN AIR FORCE RESERVE HURRICANE HUNTER...MICROWAVE SATELLITE IMAGERY...AND DATA FROM FRENCH RADAR ON MARTINIQUE SUGGEST THAT TROPICAL DEPRESSION SIX HAS AN ELONGATED LOW-LEVEL CIRCULATION...WITH THE CENTER FIXES FROM THE HURRICANE HUNTER IN THE NORTHERN PART OF THE ELONGATION. THE AIRCRAFT REPORTED A CENTRAL PRESSURE OF 1008 MB AND MAXIMUM FLIGHT-LEVEL WINDS OF 42 KT EAST OF THE CENTER. THIS DATA ALONG WITH QUIKSCAT DATA AND SUBSEQUENT SATELLITE INTENSITY ESTIMATES SHOW THAT THE DEPRESSION IS JUST BELOW TROPICAL STORM STRENGTH...AND IT COULD BECOME A TROPICAL STORM AT ANY TIME AS IT MOVES THROUGH THE WINDWARD ISLANDS. THE INITIAL MOTION IS A SOMEWHAT UNCERTAIN 280/13. THE DEPRESSION IS CURRENTLY IN A SYNOPTIC PATTERN WHICH IS SIMILAR TO THAT OF HURRICANE DEAN...ON THE SOUTH SIDE OF A WESTWARD BUILDING LOW/MID-LEVEL RIDGE. THIS PATTERN SHOULD PERSIST FOR AT LEAST FOUR DAYS... CAUSING THE TROPICAL CYCLONE TO MOVE GENERALLY WEST-NORTHWESTWARD. THE TRACK GUIDANCE IS TIGHTLY CLUSTERED THROUGH 36 HR...THEN SOME SPREAD OCCURS. THE HWRF AND THE SHALLOW AND MEDIUM MEAN LAYER BAM MODELS FORECAST A MORE NORTHWARD MOTION TO A 120 HR POSITION NEAR THE YUCATAN CHANNEL...WHILE THE REMAINDER OF THE GUIDANCE TAKES THE CYCLONE TO BELIZE AND THE SOUTHERN YUCATAN PENINSULA. THE HWRF SHOWS THE STORM DISSIPATING DURING THE FORECAST PERIOD...WHICH MAY ACCOUNT FOR ITS MORE NORTHWARD FORECAST TRACK. THE TRACK FORECAST IS DOWN THE MIDDLE OF THE REMAINDER OF THE GUIDANCE AND IS SIMILAR TO THE PREVIOUS FORECAST. THE LARGE-SCALE MODELS FORECAST THE CYCLONE TO BE IN DEEP-LAYER EASTERLY FLOW ON THE SOUTH SIDE OF AN UPPER-LEVEL ANTICYCLONE FOR THE NEXT 5 DAYS...WHICH SHOULD ALLOW SIGNIFICANT STRENGTHENING ONCE THE SYSTEM CONSOLIDATES. THE SHIPS MODEL AND THE EXPERIMENTAL LGEM MODEL BOTH FORECAST A MAJOR HURRICANE IN ABOUT 5 DAYS. ON THE OTHER HAND...AS NOTED ABOVE THE HWRF DISSIPATES THE SYSTEM...WHILE THE GFDL WAITS UNTIL IT IS WEST OF 75W TO FORECAST SIGNIFICANT STRENGTHENING. GIVEN THE GOOD OUTFLOW ALOFT AND THE FORECAST UPPER-LEVEL WINDS...THE INTENSITY FORECAST CALLS FOR STEADY STRENGTHENING THROUGH THE FORECAST PERIOD. THERE IS A CHANCE THAT THE CYCLONE COULD BE STRONGER THAN CURRENTLY FORECAST IF THE STATISTICAL MODELS ARE CORRECT. FORECAST POSITIONS AND MAX WINDS INITIAL 01/0300Z 12.0N 59.9W 30 KT 12HR VT 01/1200Z 12.5N 62.2W 35 KT 24HR VT 02/0000Z 13.2N 65.5W 40 KT 36HR VT 02/1200Z 14.0N 69.0W 50 KT 48HR VT 03/0000Z 14.6N 72.6W 55 KT 72HR VT 04/0000Z 15.5N 79.0W 60 KT 96HR VT 05/0000Z 16.5N 84.0W 70 KT 120HR VT 06/0000Z 17.5N 88.5W 80 KT...INLAND $$ FORECASTER BEVEN |
