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#108572 (Received by flhurricane at: 4:40 AM 04.Sep.2006) TCDAT1 TROPICAL DEPRESSION SIX DISCUSSION NUMBER 3 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL062006 500 AM EDT MON SEP 04 2006 CONVENTIONAL SATELLITE IMAGERY SUGGEST THAT THERE HAS BEEN LITTLE OVERALL CHANGE IN THE ORGANIZATION OF THE DEPRESSION. THE CIRCULATION CONTINUES TO BE BROAD WITH SEVERAL POSSIBLE CENTERS. ALTHOUGH BANDING FEATURES REMAIN IMPRESSIVE...THEY ARE SOMEWHAT REMOVED FROM THE ESTIMATED CENTER. BASED ON THIS ANALYSIS AND UNCHANGED DVORAK INTENSITY ESTIMATES...THE INITIAL INTENSITY REMAINS 30 KT FOR THIS ADVISORY. THE DEPRESSION APPEARS TO BE ENCOUNTERING SOME SOUTHWESTERLY SHEAR ASSOCIATED WITH AN UPPER-TROPOSPHERIC TROUGH TO THE NORTHWEST. THIS TROUGH IS EXPECTED TO SLOWLY LIFT NORTHEASTWARD OVER THE NEXT 2 TO 3 DAYS...SO VERTICAL SHEAR MAY LIMIT STRENGTHENING IN THE SHORT-TERM. LATER IN THE FORECAST PERIOD...GLOBAL MODELS INDICATE THAT THE UPPER-LEVEL ENVIRONMENT COULD BECOME MORE CONDUCIVE FOR STRENGTHENING AS A LARGE UPPER-LEVEL ANTICYCLONE FORMS OVER CYCLONE. THE OFFICIAL FORECAST IS BASED ON A BLEND OF THE SHIPS AND GFDL MODELS...AND IS ESSENTIALLY AN UPDATE OF THE PREVIOUS ADVISORY. GIVEN THE POORLY DEFINED CENTER...THE ESTIMATED INITIAL MOTION OF 310/10 IS UNCERTAIN. THE DEPRESSION IS CURRENTLY MOVING TOWARD A WEAKNESS IN THE MID-LEVEL RIDGE BETWEEN 45W-55W LONGITUDE. THIS WEAKNESS IS EXPECTED TO REMAIN ESSENTIALLY STATIONARY DURING THE NEXT 2 TO 3 DAYS ALLOWING A CONTINUATION OF THE CURRENT MOTION. THEREAFTER...A RIDGE OVER THE WESTERN ATLANTIC IS FORECAST TO SHIFT EASTWARD NORTH OF THE CYCLONE RESULTING IN A MORE WESTWARD MOTION. WHILE ALL GLOBAL MODELS AND THE GFDL ARE IN GOOD AGREEMENT ON THIS GENERAL WESTWARD TURN...NEARLY ALL OF THEM ARE NOW MUCH SLOWER IN THE FORWARD SPEED. THIS REQUIRES SOME ADJUSTMENT AND THE NEW FORECAST IS ALONG BUT SLOWER THAN THE PREVIOUS ONE. FORECAST POSITIONS AND MAX WINDS INITIAL 04/0900Z 15.6N 41.1W 30 KT 12HR VT 04/1800Z 16.5N 42.4W 30 KT 24HR VT 05/0600Z 17.5N 44.0W 35 KT 36HR VT 05/1800Z 18.4N 45.6W 45 KT 48HR VT 06/0600Z 19.0N 47.1W 55 KT 72HR VT 07/0600Z 20.0N 51.0W 60 KT 96HR VT 08/0600Z 21.0N 54.0W 70 KT 120HR VT 09/0600Z 22.0N 57.0W 75 KT $$ FORECASTER RHOME/AVILA |