000 WTNT44 KNHC 132035 TCDAT4 TROPICAL STORM NADINE DISCUSSION NUMBER 10 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142012 ISSUED BY THE HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD 500 PM AST THU SEP 13 2012 NADINE CONTINUES TO MAINTAIN THE APPEARANCE OF A STRONG TROPICAL STORM PER SATELLITE IMAGERY...AND THIS IS CONFIRMED BY DATA FROM A RECENT SCATTEROMETER OVERPASS. ALTHOUGH THE CYCLONE EXHIBITS A FAIRLY WELL DEFINED CENTRAL DENSE OVERCAST...NO EYE IS APPARENT IN EITHER VISIBLE OR INFRARED IMAGERY. WATER VAPOR IMAGERY SUGGESTS THAT VERTICAL SHEAR HAS NOT BECOME PROHIBITIVELY STRONG OVER THE STORM. THE SHEAR HAS...HOWEVER...BEEN STRONG ENOUGH TO PREVENT NADINE FROM STRENGTHENING TODAY. THE DYNAMICAL GUIDANCE DOES NOT SHOW AS MUCH SHEAR DURING THE FORECAST PERIOD AS IN PREVIOUS CYCLES. THIS LIKELY RESULTS FROM THE PREDICTION OF THE GLOBAL MODELS THAT A TROUGH TO THE WEST OF NADINE WILL DE-AMPLIFY AND PHASE WITH ANOTHER CYCLONE EXITING EASTERN CANADA. THIS WOULD LEAVE THE TROPICAL CYCLONE SOUTH OF AN AMPLIFYING RIDGE...IN AN ENVIRONMENT THAT COULD ALLOW FOR SOME RELAXATION OF THE SHEAR. THEREFORE...NADINE MAY STILL HAVE AN OPPORTUNITY TO STRENGTHEN...AS SUGGESTED BY THE OFFICIAL FORECAST. HOWEVER...IT SHOULD BE NOTED THAT THE TIMING AND DURATION OF A POTENTIAL STRENGTHENING EPISODE IS UNCERTAIN. THE MOTION CONTINUES TO BEND TOWARD THE RIGHT...AND IS NOW NEAR 325/14. THE SYNOPTIC TRACK FORECAST REASONING IS BASICALLY UNCHANGED FROM THE PREVIOUS ADVISORY...AND THE GFS AND ECMWF FORECASTS HAVE COME INTO BETTER AGREEMENT DURING THE LATTER PART OF THE FORECAST PERIOD. THE GFDL CONTINUES TO APPEAR AS A LEFT OUTLIER...ALTHOUGH NOT AS FAR LEFT AS IN ITS PREVIOUS RUN. THE OFFICIAL FORECAST TRACK HAS CHANGED VERY LITTLE...EXCEPT TO LOOP JUST SLIGHTLY FARTHER WEST DURING THE FIRST COUPLE OF DAYS...BEFORE RETURNING TO THE PREVIOUS NHC TRACK FOR DAYS 3-5. THIS FALLS BETWEEN THE LATEST TVCN CONSENSUS AND THE GFS/ECMWF TRACKS. THE SCATTEROMETER PASS SHOWED A MUCH LARGER TROPICAL CYCLONE THAN PREVIOUSLY ANALYZED...ESPECIALLY OVER THE EASTERN SEMICIRCLE WHERE TROPICAL STORM FORCE WINDS EXTEND OUTWARD AT LEAST 200 N MI. THIS IS CONSISTENT WITH THE SATELLITE PRESENTATION IN WHICH NADINE IS SEEN TO HAVE A LARGE AREA OF DEEP CONVECTION THAT EXTENDS WELL TO THE EAST AND NORTHEAST OF THE CENTER. FORECAST POSITIONS AND MAX WINDS INIT 13/2100Z 24.0N 53.0W 60 KT 70 MPH 12H 14/0600Z 25.7N 54.0W 60 KT 70 MPH 24H 14/1800Z 28.0N 54.4W 60 KT 70 MPH 36H 15/0600Z 30.1N 53.8W 65 KT 75 MPH 48H 15/1800Z 31.3N 52.0W 65 KT 75 MPH 72H 16/1800Z 32.0N 47.0W 60 KT 70 MPH 96H 17/1800Z 33.0N 41.0W 60 KT 70 MPH 120H 18/1800Z 35.0N 34.0W 60 KT 70 MPH $$ FORECASTER BURKE/PASCH