

203 

WWUS20 KWNS 130010

SEL1

SPC WW 130010

NEZ000-SDZ000-130600-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 291

NWS STORM PREDICTION CENTER NORMAN OK

710 PM CDT TUE MAY 12 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL AND NORTH CENTRAL NEBRASKA

       CENTRAL SOUTH DAKOTA



EFFECTIVE THIS TUESDAY NIGHT AND WEDNESDAY MORNING FROM 710 PM

UNTIL 100 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 60

STATUTE MILES EAST AND WEST OF A LINE FROM 10 MILES EAST OF NORTH

PLATTE NEBRASKA TO 40 MILES NORTHWEST OF ABERDEEN SOUTH DAKOTA.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU1).



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 289...WW 290...



DISCUSSION...ONGOING SEVERE STORMS/SUPERCELLS FROM CENTRAL SD INTO

CENTRAL NEB WILL LIKELY CONTINUE THROUGH EARLY TONIGHT IN ADVANCE OF

A STRONG MID LEVEL TROUGH AND ASSOCIATED SURFACE COLD FRONT.  STEEP

MID LEVEL LAPSE RATES AND 0-6 KM BULK SHEAR OF 45-60 KT WILL SUPPORT

A CONTINUED THREAT FOR SUPERCELLS AND SMALL BOWS AS THE BELT OF

ASCENT SPREADS FROM W TO E ACROSS SD AND NRN NEB...DESPITE SOMEWHAT

LIMITED MOISTURE.



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 27035.





...THOMPSON

