

926 

WWUS20 KWNS 230640

SEL4

SPC WW 230640

NEZ000-SDZ000-231300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 494

NWS STORM PREDICTION CENTER NORMAN OK

1240 AM MDT TUE JUN 23 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       WESTERN AND NORTH CENTRAL NEBRASKA

       SOUTH CENTRAL SOUTH DAKOTA



EFFECTIVE THIS TUESDAY MORNING FROM 1240 AM UNTIL 700 AM MDT.



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 NORTH AND SOUTH OF A LINE FROM 20 MILES WEST

SOUTHWEST OF ALLIANCE NEBRASKA TO 25 MILES EAST NORTHEAST OF

AINSWORTH 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.



DISCUSSION...SMALL WRN NEB MCS EXPECTED TO CONTINUE GENERALLY

ENEWD...SUPPORTED BY UPLIFT OF MOIST LOW LVL ELY FLOW ATOP NE-MOVING

SYSTEM COLD POOL.  WV IMAGERY SUGGESTS THAT MCS MAY BE

SUPPORTED...IN PART...BY ASCENT IN ENTRANCE REGION OF A NRN STREAM

JET STREAK.  GIVEN DEEP EML ABOVE MOIST LAYER...FORWARD PROPAGATING

SEGMENTS/VERY SMALL BOWS MAY YIELD A FEW SPOTS OF HIGH

WIND/MARGINALLY SVR HAIL THROUGH LATER THIS MORNING /REF MCD 1280/.



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 25025.





...CORFIDI

