http://www.spc.noaa.gov/products/watch/ww0171.html

URGENT - IMMEDIATE BROADCAST REQUESTED
   TORNADO WATCH NUMBER 171
   NWS STORM PREDICTION CENTER NORMAN OK
   630 PM CDT SAT APR 14 2012
   
   THE NWS STORM PREDICTION CENTER HAS ISSUED A
   TORNADO WATCH FOR PORTIONS OF 
   
          CENTRAL AND SOUTHEAST NEBRASKA
   
   EFFECTIVE THIS SATURDAY NIGHT AND SUNDAY MORNING FROM 630 PM
   UNTIL 200 AM CDT.
   
   ...THIS IS A PARTICULARLY DANGEROUS SITUATION...
   
   DESTRUCTIVE TORNADOES...LARGE HAIL TO 2 INCHES IN DIAMETER...
   THUNDERSTORM WIND GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE
   POSSIBLE IN THESE AREAS.
   
   THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 50 STATUTE
   MILES NORTH AND SOUTH OF A LINE FROM 15 MILES WEST OF KEARNEY
   NEBRASKA TO 40 MILES SOUTH OF OMAHA NEBRASKA.  FOR A COMPLETE
   DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE
   (WOUS64 KWNS WOU1).
   
   REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
   TORNADOES AND 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.
   
   OTHER WATCH INFORMATION...CONTINUE...WW 166...WW 167...WW
   169...WW 170...
   
   DISCUSSION...SURFACE LOW N OF GLD WILL DEVELOP NEWD INTO CNTRL NEB
   TONIGHT WITH AN ASSOCIATED WARM FRONT/OUTFLOW BOUNDARY LIFTING NWD
   THROUGH S-CNTRL/SERN NEB.  THE RETREAT OF THIS BOUNDARY WILL
   COINCIDE WITH THE WRN EXTENSION OF A 50+ KT SLY LLJ WHICH WILL
   ENHANCED VERTICAL SHEAR AND AIR MASS DESTABILIZATION.  AS
   SUCH...ENVIRONMENT IS EXPECTED TO REMAIN SUPPORTIVE OF SUPERCELLS
   CAPABLE OF TORNADOES /SOME SIGNIFICANT/ AND LARGE HAIL.
   
   AVIATION...TORNADOES AND 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
   450. MEAN STORM MOTION VECTOR 24035.