000 WTPZ42 KNHC 160854 TCDEP2 TROPICAL STORM LANE DISCUSSION NUMBER 4 NWS NATIONAL HURRICANE CENTER MIAMI FL EP122012 200 AM PDT SUN SEP 16 2012 LANE HAS BEEN MAINTAINING A BALL OF COLD-TOPPED CONVECTION TONIGHT...BUT IS LARGELY ABSENT SIGNIFICANT BANDING FEATURES. WHILE A 0506 UTC ASCAT PASS SUGGESTS THAT THE LOW-LEVEL CENTER IS EMBEDDED WITHIN THE CONVECTIVE MASS...MICROWAVE IMAGES WOULD PLACE THE CENTER CLOSER TO THE EDGE. SATELLLITE CLASSIFICATIONS HAVE INCREASED TO A CONSENSUS T3.0/45 KT FROM TAFB AND SAB. HOWEVER... SEVERAL BELIEVABLE 45-50 KT WIND VECTORS WERE PRESENT IN THE EARLIER ASCAT PASS...AND BASED ON THIS...THE INITIAL INTENSITY IS INCREASED TO 50 KT. THE DISAGREEMENT BETWEEN MICROWAVE AND ASCAT CENTER FIXES MAKES THE INITIAL MOTION ESTIMATE RATHER UNCERTAIN. A BLEND OF THESE ESTIMATES SUGGESTS A GENERALLY WESTWARD TRACK OF 280/06. LANE IS NEARING THE SOUTHWESTERN EDGE OF A WEAK MID-LEVEL RIDGE SOUTH OF BAJA CALIFORNIA WHICH HAS BEEN ERODED BY A LARGE CUT-OFF LOW OVER SUBTROPICAL PACIFIC NEAR 34N 137W. GLOBAL MODELS SHOW LANE QUICKLY GAINING LATITUDE DURING THE NEXT COUPLE OF DAYS AS IT MOVES INTO THE WEAKNESS CREATED BY THIS CUT-OFF FEATURE. AFTER 72 HOURS...THE TRACK SHOULD BEND TOWARD THE WEST AS LANE WEAKENS AND GRADUALLY BECOMES A SHALLOW CYCLONE. THE NHC TRACK FORECAST IS SIMILAR TO THE PREVIOUS ONE AND IS WEIGHTED TOWARD THE GFS/ECMWF MODELS...ON THE LEFT SIDE OF THE GUIDANCE ENVELOPE THROUGH 48 HOURS. THEREAFTER... THE TRACK FORECAST IS CLOSE TO THE MULTI-MODEL CONSENSUS TVCE. LANE HAS A LIMITED WINDOW OF OPPORTUNITY FOR STRENGTHENING. THE SHEAR IS EXPECTED TO BE LOW AND THE WATERS WARM FOR ANOTHER 36-48 HOURS. AFTER THAT TIME...THE MORE POLEWARD MOTION OF THE CYCLONE SHOULD CAUSE IT TO REACH A SHARP BOUNDARY OF SSTS. SOUTHWESTERLY SHEAR IS ALSO LIKELY TO SIGNIFICANTLY INCREASE IN ASSOCIATION WITH AN UPPER-LEVEL TROUGH TO THE NORTHWEST OF THE CYCLONE. GIVEN THE CURRENT INTENSIFICATION TREND...THE INTENSITY FORECAST UP TO 72 HR HAS BEEN ADJUSTED HIGHER EARLY IN THE FORECAST PERIOD IN BEST AGREEMENT WITH THE LGEM AND FSU SUPERENSEMBLE OUTPUT. AFTER THAT TIME...IT IS UNCHANGED FROM THE PREVIOUS ADVISORY. FORECAST POSITIONS AND MAX WINDS INIT 16/0900Z 13.3N 124.5W 50 KT 60 MPH 12H 16/1800Z 14.0N 125.4W 60 KT 70 MPH 24H 17/0600Z 14.9N 126.5W 65 KT 75 MPH 36H 17/1800Z 16.2N 127.5W 70 KT 80 MPH 48H 18/0600Z 17.8N 128.4W 60 KT 70 MPH 72H 19/0600Z 20.0N 130.3W 40 KT 45 MPH 96H 20/0600Z 20.0N 132.8W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 21/0600Z 19.5N 137.0W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ FORECASTER KIMBERLAIN