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#288663 (Received by flhurricane at: 5:01 AM 16.Aug.2009) TCDAT4 TROPICAL DEPRESSION FOUR DISCUSSION NUMBER 1 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL042009 500 AM EDT SUN AUG 16 2009 DATA FROM THE WFO TAMPA RADAR INDICATE THAT THE DISTURBANCE IN THE EASTERN GULF OF MEXICO HAS BECOME SIGNIFICANTLY BETTER ORGANIZED OVERNIGHT. A QUIKSCAT PASS NEAR 00Z SUGGESTED THAT THERE PROBABLY WAS A CLOSED SURFACE CIRCULATION. GIVEN THIS...ADVISORIES ARE BEING INITIATED ON A NEW TROPICAL DEPRESSION. ALTHOUGH THERE WAS A SHIP REPORT FROM A CARNIVAL CRUISE LINE VESSEL OF 40 KT...THIS REPORT IS NOT CONSIDERED TO BE REPRESENTATIVE OF THE SURFACE WINDS. DOPPLER VELOCITIES FROM THE TAMPA RADAR ALSO DO NOT SUPPORT TROPICAL STORM STRENGTH AT THIS TIME. HOWEVER...THE EXCELLENT RADAR PRESENTATION AND DEEP CONVECTION SUGGESTS THAT STORM STATUS IS LIKELY TO BE ATTAINED SOON. VERTICAL SHEAR IS VERY LOW...AND THE INTENSITY GUIDANCE FROM THE HWRF AND GFDL SUGGEST A MIDDLE-RANGE TROPICAL STORM BY LANDFALL. IT SHOULD BE NOTED THAT SOME ADDITIONAL STRENGTHENING PRIOR TO LANDFALL BUT AFTER THE 12 HOUR 45 KT FORECAST INTENSITY SHOWN BELOW IS LIKELY. THE INITIAL MOTION IS 330/13. THE CYCLONE IS MOVING AROUND THE PERIPHERY OF THE SUBTROPICAL RIDGE AND IS EXPECTED TO MAINTAIN THIS APPROXIMATE TRACK UNTIL LANDFALL. THE OFFICIAL FORECAST IS CLOSE TO A CONSENSUS OF A FAIRLY TIGHTLY CLUSTERED GUIDANCE SUITE. THIS IS A VERY SMALL TROPICAL CYCLONE...AND ITS EFFECTS ARE LIKELY TO REMAIN RATHER CLOSE TO THE PATH OF THE CENTER. FORECAST POSITIONS AND MAX WINDS INITIAL 16/0900Z 27.7N 83.9W 30 KT 12HR VT 16/1800Z 29.2N 85.0W 45 KT 24HR VT 17/0600Z 31.0N 86.7W 40 KT...INLAND 36HR VT 17/1800Z 33.0N 87.5W 20 KT...DISSIPATING INLAND 48HR VT 18/0600Z...DISSIPATED $$ FORECASTER FRANKLIN |