

696 

WWUS20 KWNS 122308

SEL5

SPC WW 122308

IAZ000-130600-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 295

NWS STORM PREDICTION CENTER NORMAN OK

610 PM CDT THU MAY 12 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       WESTERN AND CENTRAL IOWA



EFFECTIVE THIS THURSDAY NIGHT AND FRIDAY MORNING FROM 610 PM

UNTIL 100 AM CDT.



HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 60

MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 55

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 40 MILES SOUTH OF

WATERLOO IOWA TO 20 MILES NORTHWEST OF OMAHA NEBRASKA.  FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU5).



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 291...WW 292...WW

293...WW 294...



DISCUSSION...TSTMS EXPECTED TO INCREASE OVER REGION THROUGH MID-LATE

EVE AS LARGE SCALE ASCENT STRENGTHENS WITH THE CONTINUED SLOW EWD

MOVEMENT OF KS/NEB UPR LOW AND ASSOCIATED VORT LOBE.  WHILE DEEP

SHEAR WILL BE MODEST...IT WILL BE SUFFICIENT FOR ORGANIZED/SUSTAINED

STORMS GIVEN PERSISTENT LOW LVL CONVERGENCE/MOISTURE INFLOW AND

STEEP MID LVL LAPSE RATES.  A BRIEF TORNADO CANNOT BE RULED OUT NEAR

W-E BOUNDARY IN NRN PART OF WW AND ALONG WRN BORDER OF WW...BUT MAIN

THREAT SHOULD BE SVR HAIL.



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

TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 50

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 450. MEAN STORM

MOTION VECTOR 20020.





...CORFIDI

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