000 WTNT41 KNHC 250238 TCDAT1 TROPICAL STORM OPHELIA DISCUSSION NUMBER 17 NWS NATIONAL HURRICANE CENTER MIAMI FL AL162011 1100 PM AST SAT SEP 24 2011 IT IS UNCLEAR WHETHER OR NOT OPHELIA STILL HAS A WELL-DEFINED CENTER...BUT IN THE INTEREST OF CONTINUITY ADVISORIES ARE STILL BEING ISSUED. WITHOUT ANY NEW DATA TO CONTRADICT EARLIER ESTIMATES...THE INTENSITY IS BEING HELD AT 40 KT...AND THE INITIAL MOTION WILL BE MAINTAINED AT 295/10 KT. THE TRACK AND INTENSITY FORECASTS ARE MORE LINKED TONIGHT THAN USUAL. OPHELIA WILL BE MOVING ALONG THE SOUTHERN EDGE OF A LOW- TO MID-LEVEL AREA OF HIGH PRESSURE OVER THE NEXT FEW DAYS...AND THE EXACT TRACK WILL DEPEND ON WHAT KIND OF INTENSITY OPHELIA CAN MAINTAIN. THE GFS AND ECMWF...USUALLY THE MOST RELIABLE GLOBAL MODELS...SHOW OPHELIA CONTINUING TO BE BATTERED BY STRONG SOUTHWESTERLY OR WESTERLY SHEAR AND THEREFORE SHOW A WEAKER VORTEX MOVING FARTHER WEST. ON THE OTHER HAND...MANY OF THE OTHER MODELS INDICATE THAT OPHELIA WILL STRENGTHEN AND CONSEQUENTLY TURN NORTHWARD STEERED BY DEEPER FLOW. BASED ON THE OVERALL SYNOPTIC ENVIRONMENT AND THE MORE LIKELY SCENARIO THAT THE VERTICAL SHEAR WILL NOT DECREASE SIGNIFICANTLY IN THE COMING DAYS...THE OFFICIAL FORECAST KEEPS OPHELIA AS A LOW-END TROPICAL STORM AND LEANS IN THE DIRECTION OF THE GFS AND ECMWF...WHICH IS ALSO JUST TO THE WEST OF THE TRACK MODEL CONSENSUS. THERE IS A POSSIBILITY THAT OPHELIA COULD DEGENERATE INTO A TROUGH OF LOW PRESURE AT ANY TIME IF IT IS DETERMINED THAT IT NO LONGER HAS A WELL-DEFINED CENTER. SHOULD THAT HAPPEN...NHC WOULD NO LONGER ISSUE ADVISORIES UNLESS IT REGENERATES INTO A TROPICAL CYCLONE. FORECAST POSITIONS AND MAX WINDS INIT 25/0300Z 18.3N 58.4W 40 KT 45 MPH 12H 25/1200Z 18.9N 59.8W 40 KT 45 MPH 24H 26/0000Z 19.8N 61.3W 35 KT 40 MPH 36H 26/1200Z 20.6N 62.6W 35 KT 40 MPH 48H 27/0000Z 21.3N 63.6W 35 KT 40 MPH 72H 28/0000Z 23.0N 65.0W 40 KT 45 MPH 96H 29/0000Z 24.5N 65.5W 45 KT 50 MPH 120H 30/0000Z 26.5N 66.0W 45 KT 50 MPH $$ FORECASTER BERG