

969 

WWUS20 KWNS 110619

SEL3

SPC WW 110619

IAZ000-111300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 623

NWS STORM PREDICTION CENTER NORMAN OK

115 AM CDT MON JUL 11 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL IOWA



EFFECTIVE THIS MONDAY MORNING FROM 115 AM UNTIL 800 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 75

STATUTE MILES EAST AND WEST OF A LINE FROM 55 MILES EAST

SOUTHEAST OF OMAHA NEBRASKA TO 25 MILES NORTH NORTHEAST OF MASON

CITY IOWA.  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...THIS SEVERE THUNDERSTORM WATCH REPLACES

SEVERE THUNDERSTORM WATCH NUMBER 663.  WATCH NUMBER 663 SHOULD HAVE

BEEN NUMBERED WATCH 623.  THIS CURRENT WATCH...WATCH 623...REPLACES

WATCH 663 AT 115 AM CDT. CONTINUE...WW 618...WW 619...WW 620...WW

621...WW 622...



DISCUSSION...ERN NEB MCS EXPECTED TO CONTINUE GENERALLY E OR ENE AT

25-30 KTS...WITH ADDITIONAL STORM DEVELOPMENT EXPECTED OVER NW IA

NEAR INTERSECTION OF SYSTEM OUTFLOW BOUNDARY WITH W-E ORIENTED

BOUNDARY ASSOCIATED WITH MN/WI MCS.  DESPITE BOUNDARY LAYER

COOLING...PRESENCE OF VERY DEEP UNSTABLE LAYER ABOVE SHALLOW

NOCTURNAL INVERSION...40+ KT WLY DEEP SHEAR FOR SUSTAINED

STORMS/SUPERCELLS...AND NOCTURNALLY-ENHANCED WSWLY LLJ SUGGEST A

CONTINUED RISK FOR BOWING SEGMENTS WITH DMGG WIND AND POSSIBLY

MARGINALLY SVR HAIL.



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 550. MEAN STORM

MOTION VECTOR 26030.





...CORFIDI

