

602 

WWUS20 KWNS 280344

SEL6

SPC WW 280344

PAZ000-281100-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 246

NWS STORM PREDICTION CENTER NORMAN OK

1145 PM EDT WED APR 27 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL PENNSYLVANIA



EFFECTIVE THIS WEDNESDAY NIGHT AND THURSDAY MORNING FROM 1145 PM

UNTIL 700 AM EDT.



HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70

MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 60

STATUTE MILES EAST AND WEST OF A LINE FROM 55 MILES NORTH

NORTHWEST OF WILLIAMSPORT PENNSYLVANIA TO 10 MILES SOUTH

SOUTHEAST OF HAGERSTOWN MARYLAND.  FOR A COMPLETE DEPICTION OF

THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS

WOU6).



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 238...WW 239...WW

240...WW 241...WW 242...WW 244...WW 245...



DISCUSSION...TSTMS HAVE RECENTLY INCREASED IN COVERAGE AND INTENSITY

OVER CNTRL PA ALONG WRN EDGE OF MORE MOIST BOUNDARY LAYER

CHARACTERIZED BY DEWPOINTS IN THE MID/UPPER 60S AND MLCAPE VALUES OF

500-1000 J/KG.  CURRENT STATE COLLEGE VWP IS SHOWING RATHER STRONG

LOW AND DEEP-LAYER SHEAR...SUPPORTIVE OF SUPERCELLS AND BOWING

STRUCTURES CAPABLE OF DAMAGING WINDS AND HAIL.  A BRIEF TORNADO

REMAINS POSSIBLE...THOUGH THE GRADUALLY COOLING AIR MASS AND

RESULTANT CIN ACCUMULATION WILL PROHIBIT A MORE ROBUST THREAT.



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 22040.





...MEAD

