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#211128 (Received by flhurricane at: 4:55 AM 28.Aug.2008) TCDAT3 TROPICAL DEPRESSION EIGHT DISCUSSION NUMBER 1 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL082008 500 AM EDT THU AUG 28 2008 THE AREA OF LOW PRESSURE ASSOCIATED WITH A TROPICAL WAVE THAT HAS BEEN TRACKED WESTWARD ACROSS THE TROPICAL ATLANTIC FOR THE PAST SEVERAL DAYS HAS DEVELOPED ENOUGH SURFACE CIRCULATION AND DEEP ORGANIZED CONVECTION TO BE CLASSIFIED AS A TROPICAL DEPRESSION. A SHIP VERY NEAR THE CENTER ALSO REPORTED A PRESSURE OF 1005 MB NEAR THE CENTER. DVORAK T-NUMBERS FROM BOTH TAFB AND SAB ARE 2.5 AND 3.0 RESPECTIVELY. INITIAL INTENSITY HAS BEEN SET AT 30 KNOTS. ALTHOUGH THE CENTER IS ESTIMATED TO BE ON THE NORTHWESTERN PORTION OF THE CONVECTION...THE PREVAILING NORTHWESTERLY SHEAR OVER THE CYCLONE HAS BEEN GRADUALLY ABATING AND THE OUTFLOW IS BECOMING ESTABLISHED IN ALL QUADRANTS. MOST OF THE GLOBAL MODELS SUGGEST THAT RIDGING WILL PREVAIL ALOFT...RESULTING IN AN ENVIRONMENT OF LIGHT SHEAR. A GRADUAL INTENSIFICATION IS FORECAST IN AGREEMENT WITH THE SHIPS INTENSITY MODEL...AND THE DEPRESSION WILL LIKELY BECOME A TROPICAL STORM LATER TODAY AND COULD REACH HURRICANE INTENSITY IN 3 DAYS. THE HWRF AND GFDL MODELS ARE MORE AGGRESSIVE...PREDICTING AN INTENSE HURRICANE. THE DEPRESSION IS MOVING TOWARD THE NORTHWEST OR 305 DEGREES AT 5 KNOTS WHILE EMBEDDED WITHIN VERY LIGHT STEERING CURRENTS. THE LARGE TROUGH CURRENTLY LOCATED OVER THE WESTERN ATLANTIC IS FORECAST TO BE REPLACED BY A LARGE SUBTROPICAL RIDGE OVER THE NEXT FEW DAYS. THIS PATTERN SHOULD FORCE THE CYCLONE TO TAKE A MORE WEST-NORTHWEST TRACK IN A DAY OR SO. THE FLOW AROUND AN UPPER-LOW JUST NORTH OF PUERTO RICO COULD ALSO INDUCE SOME WESTWARD COMPONENT OVER THE NEXT FEW DAYS. BY THE END OF THE FORECAST PERIOD...THE STEERING FLOW IS EXPECTED TO WEAKEN AND THE CYCLONE COULD MEANDER FOR A WHILE. THE TRACK FORECAST IS BASICALLY IN THE MIDDLE OF THE GUIDANCE ENVELOPE WHICH INDEED SHOWS A WESTWARD TRACK BEYOND 4 DAYS. FORECAST POSITIONS AND MAX WINDS INITIAL 28/0900Z 19.8N 57.9W 30 KT 12HR VT 28/1800Z 20.5N 58.8W 35 KT 24HR VT 29/0600Z 22.0N 60.5W 40 KT 36HR VT 29/1800Z 23.5N 62.5W 45 KT 48HR VT 30/0600Z 25.0N 64.5W 55 KT 72HR VT 31/0600Z 26.0N 67.0W 70 KT 96HR VT 01/0600Z 27.0N 69.0W 75 KT 120HR VT 02/0600Z 27.0N 70.5W 75 KT $$ FORECASTER AVILA |