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| #145850 (Received by flhurricane at: 4:55 AM 14.Aug.2007) TCDAT4 TROPICAL DEPRESSION FOUR DISCUSSION NUMBER 4 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL042007 500 AM EDT TUE AUG 14 2007 LATEST SATELLITE IMAGERY INDICATES THAT THERE HAS BEEN LITTLE OVERALL CHANGE IN THE ORGANIZATION OR THE STRUCTURE OF THE DEPRESSION. THE LOW-LEVEL CIRCULATION IS STILL NOT WELL-DEFINED AND IS ELONGATED EAST TO WEST WITH ALL OF THE DEEP CONVECTION DISPLACED WEST OF THE ESTIMATED CENTER. THE INITIAL INTENSITY REMAINS 30 KT FOR THIS ADVISORY IN CONCURRENCE WITH DVORAK ESTIMATES FROM BOTH TAFB AND SAB. GLOBAL MODELS ALL INDICATE THAT THE SHEAR WILL GRADUALLY RELAX OVER THE NEXT COUPLE OF DAYS AND AN UPPER-LEVEL ANTICYCLONE WILL BUILD OVER THE CYCLONE. THIS...COMBINED WITH INCREASINGLY WARMER WATERS ALONG THE FORECAST TRACK...SHOULD CREATE A MORE FAVORABLE ENVIRONMENT FOR INTENSIFICATION. THE GFDL... HWRF...AND SHIPS MODELS ARE NOW FORECASTING PEAK INTENSITIES OF 110 KT...104 KT...AND 92 KT RESPECTIVELY. HOWEVER...CONSIDERING THE PRESENT LACK OF ORGANIZATION...THE OFFICIAL FORECAST STAYS NEAR THE LOWER END OF THE AVAILABLE INTENSITY GUIDANCE AND IS PRACTICALLY UNCHANGED FROM THE PREVIOUS ADVISORY. UNDER THE INFLUENCE OF A STRONG DEEP-LAYER RIDGE TO THE NORTH...THE DEPRESSION CONTINUES TO MOVE RAPIDLY WESTWARD OR 270/18. THIS GENERAL MOTION IS LIKELY TO CONTINUE DURING THE NEXT DAY OR TWO. THEREAFTER...A WEAKNESS IN THE RIDGE OVER THE CENTRAL ATLANTIC SHOULD CAUSE A GRADUAL TURN TOWARD THE WEST-NORTHWEST WITH A REDUCTION IN FORWARD SPEED. BY DAYS 4-5...MODELS BEGIN TO DIVERGE DUE TO DIFFERING FORECASTS OF AN MID/UPPER-LEVEL CUTOFF LOW EXPECTED TO FORM OFF THE SOUTHEASTERN UNITED STATES COAST. THE UKMET QUICKLY DISSIPATES THE LOW...ALLOWING MID-LEVEL RIDGING TO BUILD OVER THE WESTERN ATLANTIC. CONVERSELY...THE GFS SHOWS THE MID/UPPER-LEVEL LOW REMAINING STATIONARY...PRODUCING A GAP IN THE SUBTROPICAL RIDGE. THE LATEST OFFICIAL FORECAST IS NUDGED TOWARD THE MODEL CONSENSUS AND IS A LITTLE SOUTH OF...AND SLIGHTLY SLOWER THAN...THE PREVIOUS ADVISORY. FORECAST POSITIONS AND MAX WINDS INITIAL 14/0900Z 12.0N 36.8W 30 KT 12HR VT 14/1800Z 12.0N 39.3W 35 KT 24HR VT 15/0600Z 12.1N 42.1W 40 KT 36HR VT 15/1800Z 12.3N 45.0W 45 KT 48HR VT 16/0600Z 12.7N 47.9W 55 KT 72HR VT 17/0600Z 14.0N 53.5W 65 KT 96HR VT 18/0600Z 16.0N 59.0W 80 KT 120HR VT 19/0600Z 18.5N 63.5W 90 KT $$ FORECASTER RHOME |
