

392 

WWUS20 KWNS 070318

SEL3

SPC WW 070318

IAZ000-ILZ000-MOZ000-071000-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 733

NWS STORM PREDICTION CENTER NORMAN OK

1015 PM CDT SAT AUG 6 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTH CENTRAL AND SOUTHEAST IOWA

       WEST CENTRAL ILLINOIS

       NORTH CENTRAL AND NORTHEAST MISSOURI



EFFECTIVE THIS SATURDAY NIGHT AND SUNDAY MORNING FROM 1015 PM

UNTIL 500 AM 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 80

STATUTE MILES EITHER SIDE OF A LINE FROM 55 MILES SOUTHWEST OF

KNOXVILLE IOWA TO 40 MILES EAST NORTHEAST OF QUINCY ILLINOIS.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU3).



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 732...



DISCUSSION...BOWING QLCS OVER SWRN IA AND EXTREME NWRN MO IS

EXPECTED TO PROGRESS EWD WITH SOME POTENTIAL FOR NEW UPDRAFTS TO

DEVELOP ON THE SRN END OF THE LEADING CONVECTIVE LINE.  AIR MASS IS

ADVANCE OF THE SYSTEM REMAINS QUITE MOIST WITH SURFACE DEW POINTS IN

THE MID/UPPER 70S...CONTRIBUTING TO MLCAPE OF 2000-3000 J/KG.

MODERATELY STRONG WESTERLY MID LEVEL FLOW OF 35-40 KT EVIDENT IN

WIND PROFILES IS RESULTING IN SUFFICIENT VERTICAL SHEAR TO MAINTAIN

THE ORGANIZED CONVECTIVE SYSTEM.  THERE IS POTENTIAL FOR SEVERE WIND

GUSTS AND HAIL TO ACCOMPANY THE SYSTEM AS IT MOVES EWD 30-35 KT.



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 550. MEAN STORM

MOTION VECTOR 27030.





...WEISS

