WATCHES: Severe Thunderstorm Watch Number 285

WWUS20 KWNS 201727
SEL5
SPC WW 201727
MIZ000-WIZ000-LMZ000-LSZ000-210100-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 285
NWS STORM PREDICTION CENTER NORMAN OK
1225 PM CDT SUN MAY 20 2012

THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

WESTERN AND CENTRAL UPPER MICHIGAN
NORTHERN AND CENTRAL WISCONSIN
LAKE MICHIGAN
LAKE SUPERIOR

EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 1225 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 75
STATUTE MILES EAST AND WEST OF A LINE FROM 5 MILES NORTHEAST OF
HOUGHTON MICHIGAN TO 40 MILES WEST SOUTHWEST OF OSHKOSH
WISCONSIN. 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...STORMS ARE BEGINNING TO INCREASE IN COVERAGE AND
INTENSITY ALONG/AHEAD OF A COLD FRONT MOVING ACROSS WRN WI. THE
ENVIRONMENT IN THE WARM SECTOR IS MODERATELY UNSTABLE WITH MLCAPE OF
1500-2000 J/KG AND CONTINUED AFTERNOON HEATING WILL FURTHER STEEPEN
LOW LEVEL LAPSE RATES. SWLY MID LEVEL WINDS OF 40-50 KT ARE
CONTRIBUTING TO FAVORABLE DEEP LAYER SHEAR SUPPORTIVE OF ORGANIZED
CONVECTIVE STRUCTURES INCLUDING A FEW SUPERCELLS AND/OR BOW ECHOES.
THIS WILL ENHANCE WIND GUST POTENTIAL WITH STRONGER STORMS...AND
STEEP MID LEVEL LAPSE RATES ABOVE THE PBL WILL ALSO PROMOTE LARGE
HAIL AS STORMS MOVE EWD/NEWD THIS AFTERNOON.

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 500. MEAN STORM
MOTION VECTOR 22030.


...WEISS

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