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WWUS20 KWNS 152030

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SPC WW 152030

MNZ000-SDZ000-WIZ000-LSZ000-160400-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 581

NWS STORM PREDICTION CENTER NORMAN OK

330 PM CDT WED AUG 15 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       MINNESOTA

       NORTHEAST SOUTH DAKOTA

       NORTHWEST WISCONSIN

       LAKE SUPERIOR



EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 330 PM UNTIL

1100 PM CDT.



HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 75

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



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 105

STATUTE MILES EITHER SIDE OF A LINE FROM 30 MILES EAST SOUTHEAST

OF INTERNATIONAL FALLS MINNESOTA TO 15 MILES SOUTHWEST OF REDWOOD

FALLS MINNESOTA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU1).



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 580...



DISCUSSION...A STRONG COLD FRONT WILL SWEEP EAST AND SOUTHEAST

ACROSS MN...ERN SD AND INTO NWRN WI THROUGH THE EVENING HOURS.

AIRMASS AHEAD OF THE FRONT HAS BECOME MODERATELY TO STRONGLY

UNSTABLE WITH LATEST MLCAPE VALUES RANGING FROM 1000 J/KG ACROSS THE

WRN PORTION OF THE ARROWHEAD OF MN TO OVER 2000 J/KG ACROSS PARTS OF

WRN MN AND NERN SD. THIS INSTABILITY IS EXPECTED TO FUEL RAPID AND

ROBUST TSTM DEVELOPMENT ALONG THE FRONT OVER THE NEXT FEW HOURS.

THIS DEVELOPMENT WILL OCCUR COINCIDENT WITH STRENGTHENING DEEP-LAYER

SHEAR AND INCREASING ASCENT THAT SHOULD FURTHER SUPPORT STORM

ORGANIZATION AND UPDRAFT PERSISTENCE. INITIAL DISCRETE STORMS MAY BE

SUPERCELLULAR WITH ROTATING UPDRAFTS AND LARGE HAIL POTENTIAL. WITH

TIME...STORMS SHOULD BECOME INCREASINGLY LINEAR ALONG OR JUST AHEAD

OF THE FRONT WITH A SEVERE QLCS/SQUALL LINE EVOLVING. HIGH/DAMAGING

WINDS MAY ACCOMPANY THE SQUALL LINE INTO THE EVENING HOURS ACROSS

PORTIONS OF SRN MN AS WELL AS WRN WI.



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

TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 65

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM

MOTION VECTOR 26035.





...CARBIN

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