

443 

WWUS20 KWNS 301804

SEL3

SPC WW 301804

MIZ000-WIZ000-LMZ000-LSZ000-310100-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 703

NWS STORM PREDICTION CENTER NORMAN OK

105 PM CDT SAT JUL 30 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       UPPER PENINSULA OF MICHIGAN

       NORTHERN AND CENTRAL WISCONSIN

       LAKE MICHIGAN

       LAKE SUPERIOR



EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 105 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 100

STATUTE MILES EAST AND WEST OF A LINE FROM 40 MILES SOUTH

SOUTHWEST OF MOSINEE WISCONSIN TO 10 MILES NORTH OF MARQUETTE

MICHIGAN.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU3).



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...AN MCS HAS EVOLVED THIS AFTERNOON AHEAD OF MCV LOCATED

NEAR DLH.  DOWNSTREAM AIR MASS IS EXPERIENCING STRONG DAYTIME

HEATING...WHICH COMBINED WITH BOUNDARY LAYER DEWPOINTS IN THE UPPER

60S TO LOWER 70S IS RESULTING IN MLCAPE VALUES OF 2000-3500 J/KG.

GRADUALLY STRENGTHENING DEEP-LAYER WIND FIELD COMBINED WITH THE

MODERATE INSTABILITY SHOULD SUPPORT THE EWD/SEWD

PROPAGATION/MOVEMENT OF MCS WITH A THREAT FOR DAMAGING WINDS AND

SOME HAIL.



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 28030.





...MEAD

