

349 

WWUS20 KWNS 190457

SEL4

SPC WW 190457

NEZ000-191100-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 474

NWS STORM PREDICTION CENTER NORMAN OK

1155 PM CDT THU JUN 18 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       MUCH OF NEBRASKA



EFFECTIVE THIS THURSDAY NIGHT AND FRIDAY MORNING FROM 1155 PM

UNTIL 600 AM CDT.



HAIL TO 2 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 85

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 65 MILES WEST

SOUTHWEST OF MULLEN NEBRASKA TO 65 MILES NORTHEAST OF GRAND

ISLAND NEBRASKA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU4).



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 470...WW 471...WW

472...WW 473...



DISCUSSION...STORMS CONTINUE TO EXPAND ACROSS FAR NERN CO AND INTO

NEB ATTM...AS STRENGTHENING SLY LOW-LEVEL JET ACROSS WRN KS YIELDS

INCREASING ISENTROPIC ASCENT ACROSS NEB N OF A SURFACE WARM FRONT

OVER KS/SERN NEB.  WITH AMPLE INSTABILITY AND DEEP-LAYER SHEAR

SUFFICIENT FOR SUPERCELLS...LARGE HAIL AND DAMAGING WIND THREAT

SHOULD EXPAND WITH TIME IN CONJUNCTION WITH INCREASING STORM

COVERAGE OVERNIGHT.



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

TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM

MOTION VECTOR 25035.





...GOSS

