000 WTNT42 KNHC 101439 TCDAT2 TROPICAL STORM GABRIELLE DISCUSSION NUMBER 8 NWS NATIONAL HURRICANE CENTER MIAMI FL AL072013 1100 AM AST TUE SEP 10 2013 THE CONVECTIVE PATTERN OF GABRIELLE CONTINUES TO FEATURE VERY COLD CLOUD TOPS IN A CDO TYPE FEATURE. MICROWAVE AND GEOSTATIONARY SATELLITE IMAGERY CONTINUE TO SUGGEST THAT THE LOW-LEVEL CENTER IS LOCATED ON THE SOUTHWESTERN SIDE OF THE DEEP CONVECTION...AND THIS STRUCTURE IS CONSISTENT WITH THE 25 KT OR SO OF SOUTHWESTERLY SHEAR ANALYZED OVER THE SYSTEM BY UW-CIMSS. THE INITIAL INTENSITY REMAINS 35 KT IN AGREEMENT WITH THE LATEST DVORAK CLASSIFICATIONS FROM TAFB AND SAB. AN AIR FORCE RESERVE AIRCRAFT WILL INVESTIGATE GABRIELLE THIS AFTERNOON TO PROVIDE MORE DETAILED INFORMATION ON THE EXACT LOCATION AND STRENGTH OF THE CYCLONE. THE ENVIRONMENT WILL REMAIN MARGINAL FOR STRENGTHENING DURING THE NEXT COUPLE OF DAYS...AS GABRIELLE REMAINS OVER SSTS ABOVE 27C WITH MODERATE SOUTHWESTERLY TO WESTERLY VERTICAL SHEAR. THE NHC INTENSITY FORECAST IS UNCHANGED FROM THE PREVIOUS ADVISORY AND IS CLOSE TO THE CONSENSUS AIDS FOR THE FIRST 48 HOURS. LATE IN THE PERIOD...THE GLOBAL MODELS SHOW LITTLE CHANGE IN INTENSITY DURING AND AFTER EXTRATROPICAL TRANSITION...WHICH SHOULD BE COMPLETE BY 96 HOURS. GABRIELLE SHOULD DISSIPATE OR BE ABSORBED BY DAY 5. THE INITIAL MOTION ESTIMATE IS 360/10...AS THE CYCLONE IS CURRENTLY SITUATED BETWEEN A MID-LEVEL RIDGE TO THE EAST AND A MID/UPPER- LEVEL LOW TO THE WEST. THE FORWARD MOTION OF GABRIELLE WILL SLOW AS THE STEERING FLOW WEAKENS...AND THE CYCLONE SHOULD TURN GRADUALLY TOWARD THE NORTHWEST BY 48 HOURS. LATER IN THE PERIOD...GABRIELLE WILL ACCELERATE NORTHEASTWARD AHEAD OF A DEEP-LAYER TROUGH MOVING INTO EASTERN NORTH AMERICA IN 3-4 DAYS. THE NHC FORECAST IS LARGELY AN UPDATE OF THE PREVIOUS ONE THROUGH 48 HOURS AND THEN TRENDS A LITTLE SLOWER AT DAYS 3 AND 4...LYING BETWEEN THE FASTER ECMWF AND THE SLOWER TVCA MULTI-MODEL CONSENSUS. FORECAST POSITIONS AND MAX WINDS INIT 10/1500Z 30.6N 65.0W 35 KT 40 MPH 12H 11/0000Z 31.9N 64.9W 40 KT 45 MPH 24H 11/1200Z 33.1N 65.2W 45 KT 50 MPH 36H 12/0000Z 34.0N 65.8W 45 KT 50 MPH 48H 12/1200Z 35.2N 66.2W 45 KT 50 MPH 72H 13/1200Z 39.5N 65.0W 45 KT 50 MPH 96H 14/1200Z 49.0N 56.5W 45 KT 50 MPH...POST-TROP/EXTRATROP 120H 15/1200Z...DISSIPATED $$ FORECASTER BRENNAN