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URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 308

NWS STORM PREDICTION CENTER NORMAN OK

1255 PM CDT MON MAY 28 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       EXTREME NORTHEAST IOWA

       SOUTHWEST MICHIGAN UPPER PENINSULA

       MUCH OF CENTRAL AND EASTERN WISCONSIN

       LAKE MICHIGAN



EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 1255 PM UNTIL

800 PM CDT.



HAIL TO 2 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 95

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

NORTHWEST OF IRON MOUNTAIN MICHIGAN TO 25 MILES WEST OF

JANESVILLE WISCONSIN.  FOR A COMPLETE DEPICTION OF THE WATCH SEE

THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU8).



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...STRONG ASCENT ACCOMPANYING THE SHORT WAVE TROUGH MOVING

INTO ERN MN AND IA WILL LIKELY AID CONVECTIVE DEVELOPMENT ALONG AND

AHEAD OF A COLD FRONT CURRENTLY SITUATED FROM WRN WI SWWD INTO NERN

IA. AIRMASS AHEAD OF THE FRONT CONTINUES TO DESTABILIZE WITH HEATING

OF THE DAY AND SURFACE-BASED CAPE IS CURRENTLY AROUND 1000 J/KG IN

SOME LOCATIONS. A WIDE ARRAY OF MODEL GUIDANCE INDICATES A

REMARKABLY CONSISTENT SIGNAL FOR THE DEVELOPMENT AND INCREASING

COVERAGE OF DEEP CONVECTION...ESPECIALLY ACROSS NRN AND ERN

WI...THROUGH THIS AFTERNOON. THIS MODEL SIGNAL IS LIKELY A RESULT OF

FAVORABLE LARGE SCALE FORCING FOR ASCENT MOVING INTO THE REGION AND

A LACK OF STRONGER INHIBITION THAN WHAT HAS BEEN IN PLACE IN RECENT

DAYS.

AMBIENT DEEP-LAYER SHEAR OF 40KT WITHIN THE SERN FLANK OF THE LARGE

UPPER LOW TO THE WEST WILL SUPPORT INCREASING STORM ORGANIZATION

WITH SUPERCELLS AND BOWING LINE SEGMENTS POTENTIALLY EVOLVING WITH

TIME. LARGE HAIL AND LOCALLY DAMAGING WINDS MAY ACCOMPANY THE

STRONGER STORMS LATER TODAY.



AVIATION...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 450. MEAN STORM

MOTION VECTOR 24040.





...CARBIN

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