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487 

WWUS20 KWNS 242055

SEL8

SPC WW 242055

PAZ000-250400-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 138

NWS STORM PREDICTION CENTER NORMAN OK

455 PM EDT WED APR 24 2013



THE NWS STORM PREDICTION CENTER HAS ISSUED A



* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

  CENTRAL AND EASTERN PENNSYLVANIA



* EFFECTIVE THIS WEDNESDAY AFTERNOON FROM 455 PM UNTIL MIDNIGHT

  EDT.



* PRIMARY THREATS INCLUDE...

  SEVERAL DAMAGING WIND GUSTS TO 70 MPH POSSIBLE



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 60

STATUTE MILES EAST AND WEST OF A LINE FROM 30 MILES NORTHWEST OF

WILKESBARRE PENNSYLVANIA TO 35 MILES SOUTH OF HARRISBURG

PENNSYLVANIA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU8).



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.



&&



DISCUSSION...A LOW-TOPPED...PRE-FRONTAL CONVECTIVE LINE IS EVOLVING

LATE THIS AFTERNOON AHEAD OF A STRONG SHORT-WAVE TROUGH AND

ASSOCIATED MIDLEVEL JET STREAK LIFTING NEWD THROUGH THE UPPER-OH

VALLEY.  DESPITE A RELATIVELY DRY AIR MASS...THE PRESENCE OF STEEP

LOW-LEVEL LAPSE RATES AND STRONG VERTICAL SHEAR AND FORCING FOR

ASCENT WILL PROMOTE EMBEDDED BOWING STRUCTURES CAPABLE OF LOCALLY

DAMAGING WINDS.



AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 0.5 INCH. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 300. MEAN STORM

MOTION VECTOR 25040.





...MEAD

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