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#105924 (Received by flhurricane at: 5:03 PM 24.Aug.2006) TCDAT4 TROPICAL STORM DEBBY DISCUSSION NUMBER 13 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL042006 500 PM EDT THU AUG 24 2006 SATELLITE IMAGERY INDICATES THAT THERE HAS BEEN LITTLE OVERALL CHANGE IN DEBBY DURING THE LAST SEVERAL HOURS. ACCORDINGLY...THE INITIAL INTENSITY IS UNCHANGED AT 45 KT. IT WOULD APPEAR THAT SOUTHERLY SHEAR CONTINUES OVER THE CYCLONE WITH THE DEEPEST CONVECTION DISPLACED A LITTLE NORTH OF THE ESTIMATED CENTER. ADDITIONALLY...DEBBY IS EXHIBITING A BURSTING TYPE PATTERN IN ITS CONVECTIVE EVOLUTION. SINCE THE SHEAR IS NOT EXPECTED TO WEAKEN SIGNIFICANTLY IN THE SHORT-TERM...ONLY GRADUAL STRENGTHENING IS SHOWN DURING THE FIRST 2 DAYS. THE UPPER FLOW MAY BECOME A BIT MORE CONDUCIVE FOR STRENGTHENING THEREAFTER. THE BEST CHANCE FOR THIS SYSTEM TO BECOME A HURRICANE MAY NOT COME UNTIL IT NEARS A MID-LATITUDE TROUGH THAT IS EXPECTED TO DIG SOUTHWARD OVER THE CENTRAL ATLANTIC AT DAYS 4 AND 5. THIS SAME TROUGH IS ALSO EXPECTED TO RESULT IN DEBBY'S EXTRATROPICAL TRANSITION BY DAY 5. THE ONLY CHANGE TO THE OFFICIAL INTENSITY FORECAST IS TO DELAY STRENGTHENING TO A HURRICANE BY ONE DAY. THE INITIAL MOTION ESTIMATE IS 300/7. DEBBY SHOULD CONTINUE ON A GENERAL NORTHWESTWARD MOTION FOR THE NEXT COUPLE OF DAYS AS IT MOVES AROUND THE SOUTHWESTERN PERIPHERY OF A MID-LEVEL ANTICYCLONE NEAR THE AZORES. THEREAFTER...THE CYCLONE IS EXPECTED TO TURN NORTH INTO A WEAKNESS WITHIN THE SUBTROPICAL RIDGE...THEN ACCELERATE NORTHEASTWARD AHEAD OF A MID-LATITUDE TROUGH FORECAST TO DIG SOUTHWARD OVER THE CENTRAL ATLANTIC. THERE HAS BEEN NO SIGNIFICANT CHANGE TO THE TRACK GUIDANCE...WHICH REMAINS IN GOOD AGREEMENT... AND ONLY COSMETIC CHANGES TO THE OFFICIAL TRACK FORECAST. FORECAST POSITIONS AND MAX WINDS INITIAL 24/2100Z 21.3N 39.5W 45 KT 12HR VT 25/0600Z 22.3N 41.9W 45 KT 24HR VT 25/1800Z 23.8N 44.9W 45 KT 36HR VT 26/0600Z 25.4N 47.4W 50 KT 48HR VT 26/1800Z 27.1N 49.5W 55 KT 72HR VT 27/1800Z 30.9N 51.3W 55 KT 96HR VT 28/1800Z 35.0N 49.0W 65 KT 120HR VT 29/1800Z 40.1N 44.0W 65 KT...EXTRATROPICAL |