

076 

WWUS20 KWNS 210704

SEL5

SPC WW 210704

MIZ000-MNZ000-WIZ000-LSZ000-211400-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 675

NWS STORM PREDICTION CENTER NORMAN OK

205 AM CDT TUE SEP 21 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       WESTERN UPPER MICHIGAN

       EASTERN MINNESOTA

       NORTHERN AND WESTERN WISCONSIN

       LAKE SUPERIOR



EFFECTIVE THIS TUESDAY MORNING FROM 205 AM UNTIL 900 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 60

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

MINNEAPOLIS MINNESOTA TO 65 MILES EAST OF IRONWOOD MICHIGAN.  FOR

A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU5).



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.



DISCUSSION...TSTMS HAVE INCREASED IN THE PAST 30 MINUTES OVER ERN

MN...POSSIBLY IN REFLECTING FACT THAT FORCING WITH SRN STREAM

SHORTWAVE IMPULSE APPEARS TO HAVE ENCOUNTERED RESERVOIR OF HIGHER PW

OVER WW REGION.  STRENGTH OF CLOUD LAYER SHEAR AND STEEP MID LVL

LAPSE RATES SUGGEST POTENTIAL FOR SVR HAIL AND POSSIBLY SMALL BOWING

SEGMENTS WITH HIGH WIND AS FORCING CONTINUES NEWD.



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 450. MEAN STORM

MOTION VECTOR 23035.





...CORFIDI

