000 WTNT44 KNHC 080841 TCDAT4 TROPICAL STORM COLIN DISCUSSION NUMBER 18 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL042010 500 AM AST SUN AUG 08 2010 THE LOW-LEVEL CENTER OF COLIN REMAINS DISPLACED TO THE NORTH OF THE REMAINING DEEP CONVECTION...AS SHEAR AND DRY AIR CONTINUE TO INHIBIT CONVECTIVE DEVELOPMENT OVER AND WEST OF THE CENTER. THE INITIAL INTENSITY IS HELD AT 35 KT FOR THIS ADVISORY...IN AGREEMENT WITH A DVORAK ESTIMATE OF 2.5 FROM TAFB. THE ENVIRONMENT AROUND COLIN DOES NOT APPEAR CONDUCIVE FOR MORE THAN MODEST STRENGTHENING OVER THE NEXT COUPLE OF DAYS...AND THE OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS ONE...SHOWING SOME SLOW STRENGTHENING UNTIL EXTRATROPICAL TRANSITION OCCURS IN ABOUT 3 DAYS. THE CENTER IS DIFFICULT TO PINPOINT IN THE MULTI-CHANNEL INFRARED IMAGERY...BUT THE INITIAL MOTION ESTIMATE IS A LITTLE FASTER NOW...TOWARD 005 DEGREES AT 5 KT. COLIN FINALLY APPEARS TO BE RESPONDING TO THE DEEP LAYER TROUGH MOVING OFFSHORE OF THE U.S. EAST COAST...AND MOST OF THE TRACK GUIDANCE IS IN GOOD AGREEMENT ON THE GENERAL SCENARIO OF AN ACCELERATION TOWARD THE NORTH-NORTHEAST AND NORTHEAST AHEAD OF THE TROUGH. HOWEVER...THE FORWARD SPEED OF MOST OF THE GUIDANCE HAS TRENDED SLOWER WITH THIS CYCLE. THE OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS ONE...BUT TRENDS SLOWER AFTER 12 HOURS. COLIN SHOULD UNDERGO EXTRATROPICAL TRANSITION BY 72 HOURS BEFORE BEING ABSORBED BY A LARGER EXTRATROPICAL CYCLONE IN ABOUT 4 DAYS. IT IS POSSIBLE THAT THE CENTER OF COLIN COULD BECOME ELONGATED AND OPEN UP INTO A TROUGH AS IT DECOUPLES FROM THE MID-LEVEL CENTER...AS SUGGESTED BY THE UKMET MODEL. IF THIS OCCURS...COLIN COULD DISSIPATE EARLIER THAN INDICATED HERE. FORECAST POSITIONS AND MAX WINDS INITIAL 08/0900Z 30.7N 65.6W 35 KT 12HR VT 08/1800Z 31.7N 65.6W 35 KT 24HR VT 09/0600Z 33.4N 65.5W 40 KT 36HR VT 09/1800Z 36.0N 64.8W 40 KT 48HR VT 10/0600Z 38.9N 61.9W 45 KT 72HR VT 11/0600Z 46.0N 52.0W 45 KT...POST-TROP/EXTRATROP 96HR VT 12/0600Z...ABSORBED BY EXTRATROPICAL LOW $$ FORECASTER BRENNAN