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Severe Thunderstorm Watch 317
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WW0317 Radar
Hazard Tornadoes EF2+ Tornadoes
Likelihood Low Very Low
Severe Wind 65 kt+ Wind
Moderate Moderate
Severe Hail 2"+ Hail
Moderate Moderate

Note:  The expiration time in the watch graphic is amended if the watch is replaced, cancelled or extended.
Note: Click for Watch Status Reports.
   SEL7
   
   URGENT - IMMEDIATE BROADCAST REQUESTED
   SEVERE THUNDERSTORM WATCH NUMBER 317
   NWS STORM PREDICTION CENTER NORMAN OK
   225 PM CDT SAT MAY 21 2011
   
   THE NWS STORM PREDICTION CENTER HAS ISSUED A
   SEVERE THUNDERSTORM WATCH FOR PORTIONS OF 
   
          WESTERN IOWA
          EASTERN NEBRASKA
   
   EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 225 PM UNTIL
   1000 PM 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 55
   STATUTE MILES EAST AND WEST OF A LINE FROM 20 MILES SOUTH
   SOUTHEAST OF BEATRICE NEBRASKA TO 25 MILES NORTH NORTHEAST OF
   SPENCER IOWA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
   ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).
   
   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 316...
   
   DISCUSSION...TSTMS ARE DEVELOPING THIS AFTERNOON ALONG SURFACE
   CONVERGENCE ZONE ASSOCIATED WITH MIDLEVEL VORTICITY MAXIMUM
   TRANSLATING NEWD ACROSS REGION. AMBIENT AIR MASS IS MODERATELY
   UNSTABLE WITH MLCAPE VALUES OF 1500-2000 J/KG AND LITTLE OR NO
   CONVECTIVE INHIBITION.  VERTICAL SHEAR SHOULD INTENSIFY THROUGH LATE
   AFTERNOON INTO EVENING AS MIDLEVEL FLOW STRENGTHENS...RESULTING IN A
   KINEMATIC ENVIRONMENT SUPPORTIVE OF SUPERCELLS. GIVEN THE STEEP
   LAPSE RATES AND COLD MID-TROPOSPHERIC TEMPERATURES...LARGE HAIL WILL
   BE THE PRIMARY HAZARD WITH THE MOST INTENSE STORMS.
   
   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 24020.
   
   
   ...MEAD
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