WWUS20 KWNS 221946 SEL2 SPC WW 221946 NYZ000-PAZ000-LEZ000-LOZ000-230300- URGENT - IMMEDIATE BROADCAST REQUESTED SEVERE THUNDERSTORM WATCH NUMBER 212 NWS STORM PREDICTION CENTER NORMAN OK 340 PM EDT WED MAY 22 2013 THE NWS STORM PREDICTION CENTER HAS ISSUED A * SEVERE THUNDERSTORM WATCH FOR PORTIONS OF WESTERN NEW YORK NORTHEASTERN PENNSYLVANIA LAKE ERIE LAKE ONTARIO * EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 340 PM UNTIL 1100 PM EDT. * PRIMARY THREATS INCLUDE... SEVERAL DAMAGING WIND GUSTS TO 70 MPH POSSIBLE SEVERAL LARGE HAIL EVENTS TO 1.5 INCHES IN DIAMETER POSSIBLE A FEW TORNADOES POSSIBLE THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 70 STATUTE MILES NORTH AND SOUTH OF A LINE FROM 30 MILES WEST OF BUFFALO NEW YORK TO 15 MILES SOUTHEAST OF UTICA NEW YORK. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU2). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE TORNADOES. && OTHER WATCH INFORMATION...CONTINUE...WW 210...WW 211... DISCUSSION...LARGE-SCALE FORCING FOR UPWARD VERTICAL MOTION AHEAD OF A SHORT WAVE IMPULSE MOVING NORTHEAST OF THE LOWER OHIO VALLEY IS EXPECTED TO CONTRIBUTE TO INCREASING THUNDERSTORM DEVELOPMENT LATE THIS AFTERNOON AND EVENING. IN THE PRESENCE OF WEAK TO MODERATE INSTABILITY...DEEP LAYER SHEAR WILL BE SUPPORTIVE OF ORGANIZED CONVECTIVE DEVELOPMENT. A WINDOW OF OPPORTUNITY APPEARS TO EXIST FOR DISCRETE SUPERCELL DEVELOPMENT...AS SOUTHERLY 850 MB FLOW STRENGTHENS...WITH ONE OR TWO TORNADOES NOT OUT OF THE QUESTION. HOWEVER...THIS THREAT IS EXPECTED TO BE SHORT-LIVED AND FAIRLY LOCALIZED...AS BOUNDARY LAYER MIXING HAS RESULTED IN SIZABLE TEMPERATURE/DEW POINT SPREADS...WHICH PROBABLY WILL ALLOW OUTFLOW TO QUICKLY UNDERCUT MESOCYLONES. AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM MOTION VECTOR 26035. ...KERR