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URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 189

NWS STORM PREDICTION CENTER NORMAN OK

100 PM EDT MON MAY 20 2013



THE NWS STORM PREDICTION CENTER HAS ISSUED A



* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

  LOWER MICHIGAN

  LAKE HURON

  LAKE MICHIGAN



* EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 100 PM UNTIL

  800 PM EDT.



* PRIMARY THREATS INCLUDE...

  SEVERAL LARGE HAIL EVENTS WITH A FEW VERY LARGE HAIL EVENTS TO 2

    INCHES IN DIAMETER POSSIBLE

  SEVERAL DAMAGING WIND GUSTS TO 70 MPH POSSIBLE



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 75

STATUTE MILES EAST AND WEST OF A LINE FROM 60 MILES WEST

NORTHWEST OF ALPENA MICHIGAN TO 40 MILES SOUTH OF JACKSON

MICHIGAN.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU9).



PRECAUTIONARY/PREPAREDNESS ACTIONS...



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...IN THE PRESENCE OF AT LEAST MODEST DEEP LAYER

SHEAR...STORM DEVELOPMENT IS EXPECTED TO CONTINUE INCREASING IN

COVERAGE AND INTENSITY ALONG AN EASTWARD PROGRESSING WIND

SHIFT...ENHANCED BY THE LAKE BREEZE...ACROSS LOWER MICHIGAN THIS

AFTERNOON.  BENEATH FAIRLY STEEP LAPSE RATES...SURFACE HEATING OF A

MOIST BOUNDARY LAYER HAS YIELDED LARGE MIXED LAYER CAPE OF

2000-3000+ J/KG... SUPPORTIVE OF SEVERE STORMS CAPABLE OF PRODUCING

LARGE HAIL.  CONSOLIDATING CONVECTIVELY GENERATED COLD POOLS MAY

CONTRIBUTE TO INCREASING POTENTIAL FOR POTENTIALLY DAMAGING WIND

GUSTS THROUGH THE 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 24035.





...KERR

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