

469 

WWUS20 KWNS 122341

SEL4

SPC WW 122341

MNZ000-WIZ000-130400-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 604

NWS STORM PREDICTION CENTER NORMAN OK

640 PM CDT THU AUG 12 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       SOUTH CENTRAL INTO EAST CENTRAL MINNESOTA

       EXTREME WEST CENTRAL WISCONSIN



EFFECTIVE THIS THURSDAY EVENING FROM 640 PM UNTIL 1100 PM CDT.



TORNADOES...HAIL TO 2 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 70 STATUTE

MILES EAST AND WEST OF A LINE FROM 35 MILES NORTHEAST OF SAINT

CLOUD MINNESOTA TO 30 MILES SOUTHWEST OF MANKATO MINNESOTA.  FOR

A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU4).



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 602...WW 603...



DISCUSSION...A LINE OF SEVERE STORMS MOVING NEWD AT 40-45 KT WILL

LIKELY PERSIST INTO E CENTRAL MN AND THE MSP AREA THIS EVENING WITH

A CONTINUED RISK FOR DAMAGING WINDS GIVEN THE STRONG INSTABILITY AND

EFFECTIVE BULK SHEAR OF 35-40 KT.  ADDITIONALLY...LOW-LEVEL SHEAR IS

MAXIMIZED ALONG A SURFACE WARM FRONT ACROSS E CENTRAL MN IN A MOIST

ENVIRONMENT.  THERE IS SOME UNCERTAINTY REGARDING THE FUTURE OF THE

TORNADIC SUPERCELLS IN W CENTRAL MN BEYOND ABOUT 01Z GIVEN THE

PRESENCE OF THE LINE OF STORMS AND ASSOCIATED OUTFLOW APPROACHING

CENTRAL MN.  STILL...THE STRONGER LOW-LEVEL SHEAR ALONG THE SURFACE

BOUNDARY COULD PROMOTE MAINLY BRIEF TORNADOES AS IT AND THE LINE OF

STORMS INTERACT THIS EVENING.



AVIATION...TORNADOES AND 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

550. MEAN STORM MOTION VECTOR 25040.





...THOMPSON

