

000 

WWUS20 KWNS 070149

SEL2

SPC WW 070149

NEZ000-070800-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 662

NWS STORM PREDICTION CENTER NORMAN OK

850 PM CDT SUN JUL 6 2008



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTHWEST AND SOUTH CENTRAL NEBRASKA



EFFECTIVE THIS SUNDAY NIGHT AND MONDAY MORNING FROM 850 PM UNTIL

300 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 45

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 25 MILES WEST

NORTHWEST OF IMPERIAL NEBRASKA TO GRAND ISLAND NEBRASKA.  FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU2).



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 660...WW 661...



DISCUSSION...THE INTERACTION OF MERGING OUTFLOWS AND A STALLED FRONT

ACROSS SRN NEB WILL SUPPORT ADDITIONAL THUNDERSTORM DEVELOP THROUGH

THE OVERNIGHT HOURS.  THUNDERSTORM COVERAGE/INTENSITY WILL BE AIDED

BY THE APPROACH OF A WEAK SHORTWAVE TROUGH FROM THE SW AND WARM

ADVECTION ON THE NOSE OF A DEVELOPING LLJ IN KS.  MODERATE

INSTABILITY AND EFFECTIVE BULK SHEAR OF 35-40 KT ON THE COOL SIDE OF

THE STALLED FRONT SHOULD BE SUFFICIENT FOR ORGANIZED STORM

CLUSTERS...AND PERHAPS SUPERCELLS.  LARGE HAIL AND DAMAGING WINDS

WILL BE THE MAIN THREATS...THOUGH AN ISOLATED TORNADO CANNOT BE

RULED OUT GIVEN THE MOIST BOUNDARY LAYER AND POTENTIAL FOR A FEW

STORM/BOUNDARY INTERACTIONS.



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 24015.





...THOMPSON

