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   URGENT - IMMEDIATE BROADCAST REQUESTED
   SEVERE THUNDERSTORM WATCH NUMBER 820
   NWS STORM PREDICTION CENTER NORMAN OK
   220 PM MDT TUE SEP 14 2004
   
   THE NWS STORM PREDICTION CENTER HAS ISSUED A
   SEVERE THUNDERSTORM WATCH FOR PORTIONS OF 
   
          NORTHEAST COLORADO
          EXTREME NORTHWEST KANSAS
          SOUTHWEST NEBRASKA
          FAR SOUTHEAST WYOMING
   
   EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 220 PM UNTIL 900
   PM MDT.
   
   HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
   MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.
   
   THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 75 STATUTE MILES
   NORTH AND SOUTH OF A LINE FROM 10 MILES WEST NORTHWEST OF FORT
   COLLINS COLORADO TO 20 MILES NORTHEAST OF IMPERIAL NEBRASKA.
   
   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 819...
   
   DISCUSSION...STRONG SHORTWAVE TROUGH WILL ENHANCE THUNDERSTORM
   DEVELOPMENT OFF HIGHER TERRAIN WHICH WILL MOVE GENERALLY EWD ACROSS
   THE CENTRAL HIGH PLAINS THROUGH THIS EVENING.  SHEAR IS MORE THAN
   ADEQUATE FOR SUPERCELLS.  HOWEVER...WITH THE EXCEPTION OF SMALL
   CORRIDOR NEAR E-W SURFACE FRONT OVER SRN NEB PANHANDLE...PRIMARY
   THREATS WILL BE FROM LARGE HAIL AND ISOLATED DAMAGING WINDS. 
   STEEPNESS OF LAPSE RATES AND ROTATING UPDRAFTS MAY ALLOW SOME VERY
   LARGE HAIL.
   
   AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
   TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
   KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM
   MOTION VECTOR 26025.
   
   
   ...EVANS