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217 

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

