000 WTNT42 KNHC 100845 TCDAT2 TROPICAL STORM GABRIELLE DISCUSSION NUMBER 7 NWS NATIONAL HURRICANE CENTER MIAMI FL AL072013 500 AM AST TUE SEP 10 2013 DURING THE PAST 12 HOURS...INFRARED SATELLITE IMAGERY INDICATES DEEP CONVECTION HAS DEVELOPED AND PERSISTED OVER AND TO THE EAST OF THE WELL-DEFINED LOW-LEVEL CIRCULATION CENTER ASSOCIATED WITH THE REMNANTS OF GABRIELLE. IN ADDITION...AN EARLIER ASCAT OVERPASS CONTAINED SOME 34- TO 36-KT WIND VECTORS TO THE SOUTH OF THE CENTER AND OBSERVATIONS FROM NOAA BUOY 41049 LOCATED MORE THAN 100 NMI SOUTHEAST OF THE CENTER HAVE BEEN STEADILY INCREASING TO AT LEAST 31 KT OUTSIDE OF CONVECTION. BASED ON THE ABOVE DATA...ADVISORIES HAVE BEEN RE-INITIATED ON TROPICAL STORM GABRIELLE. AN AIR FORCE RESERVE AIRCRAFT IS SCHEDULED TO RECONNOITER THE CYCLONE THIS AFTERNOON TO PROVIDE MORE DETAILED INFORMATION ON THE EXACT LOCATION AND STRENGTH OF GABRIELLE. THE INITIAL MOTION ESTIMATE IS 360/10 KT...WHICH IS BASED MAINLY ON LIMITED MICROWAVE FIXES. THE NHC MODEL GUIDANCE IS IN VERY GOOD AGREEMENT ON GABRIELLE MOVING NORTHWARD TO NORTH-NORTHWESTWARD AND SLOWING DOWN DURING THE NEXT 36 TO 48 HOURS AS THE CYCLONE MOVES AROUND THE EASTERN PERIPHERY OF A RETROGRADING MID-/UPPER-LEVEL LOW CURRENTLY LOCATED JUST NORTH OF THE BAHAMAS. ON THE FORECAST TRACK...GABRIELLE IS EXPECTED TO PASS OVER OR NEAR BERMUDA IN ABOUT 24 HOURS. BY 72 HOURS...GABRIELLE IS FORECAST TO BEGIN TO LIFT OUT AND ACCELERATE NORTHWARD AND THEN NORTHEASTWARD AHEAD OF A STRONG MID-TROPOSPHERIC TROUGH AND FRONTAL SYSTEM THAT IS FORECAST TO MOVE OFF OF THE U.S. EAST COAST BY 96 HOURS. THE OFFICIAL FORECAST TRACK IS CLOSE TO THE MULTI-MODEL CONSENSUS TVCA. GABRIELLE IS EXPECTED TO REMAIN IN A MODERATE SHEAR ENVIRONMENT BUT OVER 28-29C SSTS FOR THE NEXT 24 HOURS OR SO...WHICH SHOULD ALLOW FOR SOME ADDITONAL STRENGTHENING TO OCCUR. THE INTENSITY IS EXPECTED TO LEVEL OFF BY 48 HOURS AS SOUTHWESTERLY VERTICAL WIND SHEAR BEGINS TO GRADUALLY INCREASE AHEAD OF THE AFOREMENTIONED APPROACHING FRONTAL SYSTEM. AT 72 HOURS AND BEYOND...GABRIELLE WILL BE MOVING OVER SUB-25C SSTS AND THE CYCLONE IS FORECAST TO BECOME A POST-TROPICAL/EXTRATROPICAL LOW BY 96 HOURS WHEN WATER TEMPERATURES WILL BE LESS THAN 20C. THE NHC INTENSITY FORECAST IS CLOSE TO THE CONSENSUS MODEL ICON. FORECAST POSITIONS AND MAX WINDS INIT 10/0900Z 29.6N 65.0W 35 KT 40 MPH 12H 10/1800Z 31.1N 65.0W 40 KT 45 MPH 24H 11/0600Z 32.7N 65.2W 45 KT 50 MPH 36H 11/1800Z 33.7N 65.7W 45 KT 50 MPH 48H 12/0600Z 34.5N 66.3W 45 KT 50 MPH 72H 13/0600Z 37.7N 65.9W 45 KT 50 MPH 96H 14/0600Z 46.8N 58.6W 45 KT 50 MPH...POST-TROP/EXTRATROP 120H 15/0600Z 56.5N 41.9W 45 KT 50 MPH...POST-TROP/EXTRATROP $$ FORECASTER STEWART