000 WTNT44 KNHC 060345 TCDAT4 TROPICAL STORM COLIN DISCUSSION NUMBER 9 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL042010 1100 PM AST THU AUG 05 2010 COLIN HAS MAINTAINED A SATELLITE CLOUD SIGNATURE SIMILAR TO WHEN A RECONNAISSANCE AIRCRAFT INVESTIGATED THE SYSTEM 6 HOURS AGO. SINCE THEN...A STRONG BURST OF DEEP CONVECTION HAS DEVELOPED IN THE NORTHEASTERN QUADRANT...ALTHOUGH THE CONVECTION HAS WANED A LITTLE DURING THE PAST COUPLE OF HOURS. HOWEVER...THE STRONG PRESSURE GRADIENT IN THE EASTERN SEMICIRCLE BETWEEN THE CENTER OF COLIN AND NOAA BUOY 41049 LOCATED 225 NMI TO THE NORTHEAST SUPPORTS KEEPING THE INTENSITY AT 50 KT. THE INITIAL MOTION ESTIMATE IS 340/12. THERE IS NO SIGNIFICANT CHANGE TO THE PREVIOUS FORECAST TRACK OR REASONING. COLIN IS EXPECTED TO GRADUALLY SLOW DOWN AND TURN NORTHWARD TOWARD A DEVELOPING WEAKNESS IN THE SUBTROPICAL RIDGE OVER THE NEXT 48 HOURS...AND THEN RECURVE TO THE NORTHEAST OVER THE NORTH ATLANTIC BY 72 HOURS AHEAD OF AN EASTWARD-MOVING MID-LATITUDE SHORTWAVE TROUGH CURRENTLY MOVING ACROSS GREAT LAKES AND OHIO VALLEY REGIONS. THE MODELS REMAIN IN GOOD AGREEMENT ON THIS SCENARIO...AND THE FORECAST TRACK WAS ONLY NUDGED SLIGHTLY TO THE EAST THROUGH 48 HOURS DUE TO THE MORE EASTWARD INITIAL POSITION. COLIN IS EXPECTED TO PASS JUST WEST OF BERMUDA IN 36-48 HOURS...BUT ONLY A SLIGHT DEVIATION TO THE EAST COULD BRING THE CENTER OVER BERMUDA. SOUTHWESTERLY VERTICAL SHEAR OF 20-25 KT CONTINUES TO HINDER SIGNIFICANT INTENSIFICATION OF COLIN...AND THESE UNFAVORABLE CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THE NEXT 24 HOURS. HOWEVER...FROM 36 TO 48 HOURS...ALL OF THE GLOBAL MODELS ARE FORECASTING THE VERTICAL SHEAR TO WEAKEN SIGNIFICANTLY AS COLIN PASSES BETWEEN TWO UPPER-LEVEL LOWS AND MOVES UNDER A SMALL RIDGE...WHICH PROVIDES A BRIEF WINDOW OF OPPORTUNITY FOR COLIN TO STRENGTHEN. THE SHIPS AND LGEM MODELS BRING COLIN TO NEAR 60 KT BY 48 HOURS...WHEN THE CYCLONE IS NEAR BERMUDA...AND THIS TREND WAS FOLLOWED FOR THIS ADVISORY PACKAGE. FORECAST POSITIONS AND MAX WINDS INITIAL 06/0300Z 26.3N 66.6W 50 KT 12HR VT 06/1200Z 27.4N 66.9W 50 KT 24HR VT 07/0000Z 29.1N 67.0W 50 KT 36HR VT 07/1200Z 30.7N 66.8W 55 KT 48HR VT 08/0000Z 32.6N 66.1W 60 KT 72HR VT 09/0000Z 37.2N 63.5W 60 KT 96HR VT 10/0000Z 43.0N 57.0W 55 KT 120HR VT 11/0000Z 50.5N 45.0W 50 KT...POST-TROP/EXTRATROP $$ FORECASTER STEWART