

966 

WWUS20 KWNS 242034

SEL6

SPC WW 242034

IAZ000-ILZ000-WIZ000-250300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 296

NWS STORM PREDICTION CENTER NORMAN OK

335 PM CDT THU MAY 24 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL AND EASTERN IOWA

       EXTREME NORTHWEST ILLINOIS

       SOUTHWEST WISCONSIN



EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 335 PM UNTIL

1000 PM CDT.



HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 75

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 45 MILES WEST

NORTHWEST OF LONEROCK WISCONSIN TO 35 MILES SOUTH SOUTHWEST OF

OTTUMWA IOWA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU6).



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 295...



DISCUSSION...STORMS ARE DEVELOPING ALONG AN EWD MOVING COLD FRONT

OVER THE CENTRAL PARTS OF IA AND ACTIVITY IS EXPECTED TO INTENSIFY

THROUGH THE LATE AFTERNOON HOURS.  CONVECTION WILL BE MOVING INTO AN

ENVIRONMENT CHARACTERIZED BY SBCAPE OF 1500-2000 J/KG AND VERY

STRONG LOW AND MID LEVEL SHEAR.  LOW LEVEL INVERTED-V SOUNDINGS WILL

AID IN DEVELOPMENT OF STRONG DOWNDRAFTS...ESPECIALLY OVER ERN IA

WHERE DCAPE EXCEEDS 1000 J/KG.  DAMAGING WIND GUSTS AND OCCASIONAL

HAIL WILL BE THE PRIMARY SEVERE THREATS.



AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 65

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM

MOTION VECTOR 22040.





...WEISS

