August 23, 2011 Severe Weather

The Severe Weather of August 23, 2011

What Happened?

During the late afternoon and evening of August 23rd, a warm front lifted north through central Wisconsin. At the same time, a strong upper level disturbance was moving across the Upper Midwest and northern Great Lakes. These two features combined to generate scattered severe thunderstorms over central Wisconsin that then moved off into east central Wisconsin during the evening.

The storms initially produced large hail, some of which were the size of golf balls near Thorp in the northwestern section of Clark County. As the storms continued to move southeast, a tornado formed 7 miles northwest of Chili at about 5:05pm. This EF2 tornado traveled approximately 7.2 miles east-southeastward before it ended around 5:30pm about 2 miles north-northeast of Chili. The maximum width of this tornado was around 200 yards and had winds estimated at between 120 and 130 mph. The tornado knocked a house off its foundation, blew roofs off houses, destroyed or damaged barns and trees, and power lines were blown down. In addition, two people suffered minor injuries.

Shortly after this damage occurred, the storm began to weaken as it moved off into Wood and Jackson Counties. Another storm developed as the first one was dissipating, which tracked across southern Clark county into northern Jackson county. This storm produced walnut sized hail in Neillsville. The storm weakened as it left Jackson county and entered northern Juneau county.

Below are maps of the approximate track of the tornado near Chili (click to enlarge).

Radar Imagery

Below are a pair of radar loops from the two main storms that developed. The radar loop on the left shows the progression of the supercell thunderstorm that developed the Chili tornado, while the radar loop on the right shows the progression of the supercell that tracked across southern Clark and northern Jackson counties.


Click on image for a loop of the radar reflectivity with the Chili Supercell	Click on image for a loop of the radar reflectivity with the Neillsville Supercell

Images

Tornado evidence in the corn, beginning of track.	First barn to suffer a direct hit from tornado near Bobwhite Rd and Pelsdorf Ave.	Damage to mobile home storage unit near Bobwhite Rd. and Romadka Ave.	Home just missed as tornado passed to the south 100 yds.	Heavy damage to residence about 3 miles into tornado track. Higher end EF-2 damage near Bobwhite Rd and Catlin Ave.
Closer image of higher end EF-2 damage near Bobwhite Rd and Catlin Ave.Top floor and roof missing. Two persons survived in basement.	Second residence with heavy damage near Heintown Rd and Division Ave. Unanchored home was slid about 20 feet off foundation. EF-1 to EF-2 damage in this vicinity with 200 yard tornado width.	Larger picture of second residence with heavy damage near Heintown Rd and Division Ave. Facing due east along tornado path.	West side of second residence with heavy damage near Heintown Rd and Division Ave. Two persons survived in the house.	Forwarded by WSAW
Forwarded by WSAW	Forwarded by WSAW	Photo of Supercell near Neillsville taken from jet at 40,000ft.	Photo of Supercell near Neillsville taken from jet at 40,000ft.	Radar image of the supercell

Damage Reports

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE LA CROSSE WI
856 PM CDT TUE AUG 23 2011

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0424 PM     HAIL             THORP                   44.96N 90.80W
08/23/2011 M1.75 INCH       CLARK              WI   TRAINED SPOTTER

0444 PM     HAIL             3 S THORP               44.92N 90.80W
08/23/2011 M1.00 INCH       CLARK              WI   LAW ENFORCEMENT

0501 PM     HAIL             LOYAL                   44.74N 90.50W
08/23/2011 M1.00 INCH       CLARK              WI   PUBLIC

0515 PM     TORNADO          5 NW CHILI              44.68N 90.42W
08/23/2011                   CLARK              WI   PUBLIC

0520 PM     TSTM WND DMG     1 S CHILI               44.62N 90.35W
08/23/2011                   CLARK              WI   TRAINED SPOTTER

0520 PM     TSTM WND DMG     1 S CHILI               44.62N 90.35W
08/23/2011                   CLARK              WI   TRAINED SPOTTER

            POWER LINES DOWN ON PINE CREEK ROAD AND COUNTY Y

0530 PM     TORNADO          CHILI                   44.63N 90.35W
08/23/2011                   CLARK              WI   EMERGENCY MNGR

            HOUSE OFF FOUNDATION...POWER LINES DOWN...ROOFS OFF
            HOUSES...AND BARNS DESTROYED

0544 PM     HAIL             NEILLSVILLE             44.56N 90.59W
08/23/2011 M1.25 INCH       CLARK              WI   TRAINED SPOTTER

0558 PM     TSTM WND DMG     2 NE CHILI              44.65N 90.32W
08/23/2011                   CLARK              WI   TRAINED SPOTTER

            POWER LINES DOWN. POSSIBLE TORNADO DAMAGE.

National Weather Service Weather Forecast Office