

000 

WWUS20 KWNS 210114

SEL6

SPC WW 210114

IAZ000-210700-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 626

NWS STORM PREDICTION CENTER NORMAN OK

810 PM CDT MON AUG 20 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       WESTERN AND CENTRAL IOWA



EFFECTIVE THIS MONDAY NIGHT AND TUESDAY MORNING FROM 810 PM UNTIL

200 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 85

STATUTE MILES EAST AND WEST OF A LINE FROM 25 MILES NORTH

NORTHWEST OF SPENCER IOWA TO 5 MILES EAST SOUTHEAST OF LAMONI

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 622...WW 623...WW

624...WW 625...



DISCUSSION...LINEAR MCS NOW NEAR OMA SHOULD CONTINUE E INTO VERY

UNSTABLE/HI PW AIR OVER W CNTRL/SW IA...WITH AN ATTENDANT THREAT FOR

HIGH WIND/HEAVY RAIN AND POSSIBLY SVR HAIL AND/OR A BRIEF SPIN-UP

TORNADO.  FARTHER N... OTHER STORMS EXPECTED TO DEVELOP/SPREAD E

INTO NW IA...WHERE SLIGHTLY STRONGER DEEP WNWLY SHEAR IS PRESENT

CLOSER TO MAIN UPR JET...BUT LOW-LVL INSTABILITY IS MORE LIMITED.

THIS ACTIVITY MAY REMAIN SEMI-DISCRETE FOR A COUPLE HOURS AND POSE A

THREAT FOR HAIL/LOCALLY DAMAGING WIND AND POSSIBLY A BRIEF TORNADO

BEFORE MERGING INTO A SMALL CLUSTER OR TWO WITH HEAVY RAIN/LOCALLY

DAMAGING WIND.



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 500. MEAN STORM

MOTION VECTOR 27025.





...CORFIDI

