SEL8
   
   URGENT - IMMEDIATE BROADCAST REQUESTED
   SEVERE THUNDERSTORM WATCH NUMBER 558
   NWS STORM PREDICTION CENTER NORMAN OK
   915 PM CDT WED JUN 29 2005
   
   THE NWS STORM PREDICTION CENTER HAS ISSUED A
   SEVERE THUNDERSTORM WATCH FOR PORTIONS OF 
   
          CENTRAL AND EASTERN IOWA
          EXTREME SOUTHWEST WISCONSIN
   
   EFFECTIVE THIS WEDNESDAY NIGHT AND THURSDAY MORNING FROM 915 PM
   UNTIL 300 AM CDT.
   
   HAIL TO 1.5 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 70
   STATUTE MILES EAST AND WEST OF A LINE FROM 70 MILES NORTH
   NORTHEAST OF WATERLOO IOWA TO 25 MILES EAST OF LAMONI IOWA.  FOR A
   COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
   UPDATE (WOUS64 KWNS WOU8).
   
   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 554...WW 555...WW 556...WW
   557...
   
   DISCUSSION...BROKEN BAND OF STORMS APPROACHING CENTRAL IA MAY
   PERSIST FOR SEVERAL HOURS WITH A THREAT FOR DAMAGING WINDS/LARGE
   HAIL...BEFORE THE BOUNDARY LAYER GRADUALLY STABILIZES OVERNIGHT. 
   THE COMBINATION OF VERTICAL SHEAR AND INSTABILITY ARE ALSO
   SUPPORTIVE OF SUPERCELLS...WHICH MAY ENHANCE THE LARGE HAIL THREAT. 
   OTHER ELEVATED STORMS FORMING IN NE IA WILL SPREAD INTO SW WI IN THE
   NEXT 2-3 HOURS.
   
   AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
   TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
   KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM
   MOTION VECTOR 25030.
   
   
   ...THOMPSON