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000 

WWUS20 KWNS 030421

SEL9

SPC WW 030421

IAZ000-MNZ000-NEZ000-SDZ000-031100-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 799

NWS STORM PREDICTION CENTER NORMAN OK

1115 PM CDT SAT AUG 2 2008



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHWEST IOWA

       SOUTHWEST MINNESOTA

       NORTHEAST NEBRASKA

       SOUTHEAST SOUTH DAKOTA



EFFECTIVE THIS SATURDAY NIGHT AND SUNDAY MORNING FROM 1115 PM

UNTIL 600 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 120

STATUTE MILES EAST AND WEST OF A LINE FROM 30 MILES NORTH

NORTHEAST OF MITCHELL SOUTH DAKOTA TO 45 MILES SOUTH OF YANKTON

SOUTH DAKOTA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU9).



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 796...WW 798...



DISCUSSION...LONG-LIVED CLUSTER OF STORMS NOW IN N CNTRL NEB MAY

INCREASE IN STRENGTH/COVERAGE AS IT MOVES FARTHER ENE INTO

STRENGTHENING WAA ZONE OVER THE MID MO VLY.  IN THIS REGION...STORMS

WILL ENCOUNTER SUBSTANTIALLY INCREASED MOISTURE RELATIVE TO POINTS

FARTHER W.  WHILE REGION IS CAPPED UNFORCED SFC PARCELS...GIVEN

DEGREE OF POTENTIAL INSTABILITY/HI PWS...AND STRENGTHENING

LLJ...SETUP MAY SUPPORT DEVELOPMENT INTO A LARGER MCS CONTAINING

HIGH WIND...AND POSSIBLY HAIL OR AN ISOLD TORNADO.



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

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