

598 

WWUS20 KWNS 082052

SEL8

SPC WW 082052

MNZ000-WIZ000-090300-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 678

NWS STORM PREDICTION CENTER NORMAN OK

345 PM CDT SAT AUG 8 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       EASTERN MINNESOTA

       WESTERN WISCONSIN



EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 345 PM UNTIL

1000 PM CDT.



TORNADOES...HAIL TO 3 INCHES IN DIAMETER...THUNDERSTORM WIND

GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE

AREAS.



THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 75 STATUTE

MILES NORTH AND SOUTH OF A LINE FROM 35 MILES NORTH NORTHWEST OF

MANKATO MINNESOTA TO 60 MILES EAST OF EAU CLAIRE WISCONSIN.  FOR

A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU8).



REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR

TORNADOES AND 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.



OTHER WATCH INFORMATION...CONTINUE...WW 677...



DISCUSSION...UPPER IMPULSE OVER THE ERN DAKOTAS IS EXPECTED TO AID

IN INCREASED STORM DEVELOPMENT ACROSS ERN MN AND WRN WI INTO THE

EVENING HOURS. EFFECTIVE SHEAR NEAR 50 KT AND EXTREME INSTABILITY

AROUND 5000 J/KG WILL BE FAVORABLE FOR INTENSE SUPERCELLS WITH VERY

LARGE HAIL AND WIND DAMAGE. ALTHOUGH THE LOW LEVEL SHEAR IS ONLY

AROUND 15 KT...THE PRESENCE OF LOW LEVEL BOUNDARIES AND AMOUNT OF

INSTABILITY MAY COMPENSATE FOR THE WEAKER LOW LEVEL SHEAR AND YIELD

A COUPLE OF TORNADOES.



AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL

SURFACE AND ALOFT TO 3 INCHES. EXTREME TURBULENCE AND SURFACE

WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO

550. MEAN STORM MOTION VECTOR 24035.





...IMY

