

311 

WWUS20 KWNS 300132

SEL7

SPC WW 300132

IAZ000-MOZ000-300700-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 117

NWS STORM PREDICTION CENTER NORMAN OK

830 PM CDT THU MAR 29 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTH CENTRAL IOWA

       NORTH CENTRAL MISSOURI



EFFECTIVE THIS THURSDAY NIGHT AND FRIDAY MORNING FROM 830 PM

UNTIL 200 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 50

STATUTE MILES EAST AND WEST OF A LINE FROM 5 MILES EAST OF DES

MOINES IOWA TO 45 MILES SOUTH SOUTHEAST OF LAMONI 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 115...WW 116...



DISCUSSION...A CLUSTER OF SEVERE STORMS IN SW IA/NW MO IS EXPECTED

TO SPREAD EWD OVER SRN IA/NRN MO IN CONJUNCTION WITH LOW-LEVEL WAA

AND ASCENT IN ADVANCE OF A MIDLEVEL TROUGH CROSSING NEB.  THE

CONVECTION WILL BECOME MORE ELEVATED WITH EWD EXTENT...BUT WILL BE

FED BY MODERATE INSTABILITY BASED AROUND 850 MB PER THE 00Z TOP

SOUNDING.  LARGE HAIL WILL BE THE MAIN THREAT...BUT ISOLATED

DAMAGING GUSTS WILL ALSO BE POSSIBLE IF STORMS CAN GROW UPSCALE INTO

A SMALL MCS CLOSE TO THE WARM FRONT ALONG THE MO/IA BORDER LATER

TONIGHT.



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 27025.





...THOMPSON

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