Milwaukee/Sullivan, WI

Weather Forecast Office

Tornado and Wind Damage Across Far Southern Wisconsin on Monday, August 10th (Updated 2 PM 8/12)

Damaging Winds and a Couple of Brief Tornadoes Across Southern Wisconsin

A cluster of strong thunderstorms evolved into a line as they tracked across southern Wisconsin on Monday, August 10th, 2020. The storms produced damaging winds and a couple of brief tornadoes. The counties hardest hit were right along the WI/IL border: Lafayette, Green, Rock, Walworth, Racine, and Kenosha Counties.

These strong thunderstorms evolved from several thunderstorms over southern Minnesota and northern Iowa early on Monday into a widespread, long-lived wind storm, or "Derecho". For more information on Derechoes, check out the Storm Prediction Center Derecho Facts Page.

Radar Animation

Tornado
Wind
Heavy Rainfall
Storm Reports

Tornadoes:

Tornado - 1 S Lake Geneva
Walworth County

Date	8/10/2020
Time (Local)	3:38 PM - 3:42 PM
EF Rating	EF-0
Est. Peak Winds	80 MPH
Path Length	3.3 miles
Max Width	50 yards
Injuries/Deaths	None
Summary: A bowing line segment was moving north-northeast out of northern Illinois and into southeast Wisconsin. There were scattered thunderstorms already ongoing across southern Wisconsin. The collision of these two storm systems caused a brief tornado in the Lake Geneva area. The storm survey crew found damage consistent with a high-end EF-0 tornado in the southern Lake Geneva area. Winds upwards of 80 mph occurred and much of the damage was to trees. Large limbs and tree trunks were knocked down or snapped.

Downloadable KMZ File


Lake Geneva Blvd	W South St & Lake Geneva Blvd	W South St	Mobile St

Tornado - 2 SSW Camp Lake
Kenosha County

Date	8/10/2020
Time (Local)	3:41 PM - 3:48 PM
EF Rating	EF-1
Est. Peak Winds	90 MPH
Path Length	3.75 miles
Max Width	150 yards
Injuries/Deaths	None
Summary: This tornado developed along the leading edge of a line of thunderstorms rolling across northern Illinois. The strengthening rear inflow jet along the apex of a bowing line segment allowed for the development of a brief tornado near Wonder Lake in northern Illinois and tracked northeast into the Camp Lake, Wisconsin area before dissipating. The damage to buildings and trees were consistent with the rating of a low end EF-1 tornado in northern Illinois, just south of the Wisconsin state line. There was mainly tree damage in the Camp Lake area, and it was consistent with an EF-0 tornado rating with winds around 80 mph.

Downloadable KMZ File


Camp Lake 117th St	Camp Lake 115th Pl	Camp Lake Wilmot Rd	Camp Lake 117th St

The Enhanced Fujita (EF) Scale classifies tornadoes into the following categories:

EF0 Weak 65-85 mph	EF1 Moderate 86-110 mph	EF2 Significant 111-135 mph	EF3 Severe 136-165 mph	EF4 Extreme 166-200 mph	EF5 Catastrophic 200+ mph

Wind:

Wind

Wind damage was reported in the following areas:

Lafayette County - Belmont, Darlington, Gratiot, South Wayne
Green County - Browntown, Monroe, Juda
Walworth County - Darien, Lake Geneva, Pell Lake
Kenosha County - Camp Lake, Trevor, Paddock Lake, Kenosha
Racine County - Union Grove, Racine.


Lake Geneva (Courtesy Ryan T)	Camp Lake (Courtesy Spencer D)	Mt. Pleasant (Courtesy Andrew M)	Mt. Pleasant (Courtesy Andrew M)

Pell Lake (Courtesy David S)	Racine (Courtesy Susan F)	Salem (Courtesy Sally G)	Troy (Courtesy Melissa E)

Hail

There was no significant hail reported with this event.

Heavy Rainfall:

Heavy rain caused street flooding in portions of southern Wisconsin. Janesville, Elkhorn, and the greater Racine area all reported some flooding.


Caledonia	Oak Creek (Courtesy of Matt K)

Elkhorn (Courtesy of April W)	Caledonia

Storm Reports

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
241 PM CDT TUE AUG 11 2020

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

0345 PM     TORNADO          2 SSW CAMP LAKE         42.50N 88.16W
08/10/2020                   KENOSHA            WI   NWS STORM SURVEY

            DAMAGE TO BUILDINGS AND TREES CONSISTENT
            WITH A LOW END EF-1 TORNADO OCCURRED IN
            NORTHERN ILLINOIS JUST SOUTH OF THE
            WISCONSIN STATE LINE. THIS TORNADO PROCEEDED
            NE INTO WISCONSIN TOWARDS CAMP LAKE WHERE
            MAINLY TREE DAMAGE WAS OBSERVED THAT IS
            CONSISTENT WITH AN EF-0 TORNADO AND WINDS OF
            80 MPH. THE POINT IS PLACED BETWEEN THE TWO
            CENTERS OF DAMAGE.



PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1030 AM CDT TUE AUG 11 2020

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

0338 PM     TORNADO          1 S LAKE GENEVA         42.58N 88.43W
08/10/2020                   WALWORTH           WI   NWS STORM SURVEY

            STORM SURVEY CREW FOUND DAMAGE CONSISTENT
            WITH A HIGH END EF-0 IN LAKE GENEVA. WINDS
            UPWARDS OF 80 MPH OCCURRED AND MUCH OF THE
            DAMAGE WAS TO TREES. LARGE LIMBS AND TREE
            TRUNKS KNOCKED DOWN OR SNAPPED. TIME IS
            ESTIMATED OFF OF RADAR.


PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
922 PM CDT MON AUG 10 2020

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

0225 PM     TSTM WND GST     3 ENE MONROE            42.62N 89.59W
08/10/2020  M62 MPH          GREEN              WI   MESONET



0220 PM     TSTM WND DMG     MONROE                  42.60N 89.64W
08/10/2020                   GREEN              WI   PUBLIC

            SOCIAL MEDIA REPORT OF A DOWNED TREE IN
            MONROE, WI. TIME ESTIMATED BASED ON RADAR.

0455 PM     HEAVY RAIN       KENOSHA                 42.59N 87.82W
08/10/2020  E2.55 INCH       KENOSHA            WI   PUBLIC

            RAINFALL AS 4:55 PM.

0409 PM     TSTM WND GST     POWERS LAKE             42.54N 88.30W
08/10/2020  E60 MPH          KENOSHA            WI   PUBLIC



0407 PM     TSTM WND DMG     1 WNW KENOSHA           42.59N 87.83W
08/10/2020                   KENOSHA            WI   PUBLIC

            LARGE TREE BRANCHES DOWN IN THE CITY OF
            KENOSHA. REPORT RELAYED VIA SOCIAL MEDIA.

0355 PM     TSTM WND GST     PADDOCK LAKE            42.58N 88.11W
08/10/2020  E70 MPH          KENOSHA            WI   PUBLIC



0352 PM     TSTM WND DMG     1 E POWERS LAKE         42.54N 88.28W
08/10/2020                   KENOSHA            WI   PUBLIC

            TREES DOWN AROUND THE INTERSECTION OF HWY Z
            AND HWY P IN POWERS LAKE.

0347 PM     TSTM WND DMG     1 SE CAMP LAKE          42.52N 88.14W
08/10/2020                   KENOSHA            WI   PUBLIC

            TREE SNAPPED AT LOCATION. REPORT RELAYED VIA
            SOCIAL MEDIA. TIME ESTIMATED FROM RADAR.

0345 PM     FLOOD            2 SSW CAMP LAKE         42.51N 88.16W
08/10/2020                   KENOSHA            WI   PUBLIC

            NUMEROUS TREES DOWN AND SNAPPED AT WILMOT
            AND 286TH. REPORT RELAYED VIA SOCIAL MEDIA.
            TIME ESTIMATED FROM RADAR.

0129 PM     TSTM WND DMG     DARLINGTON              42.68N 90.12W
08/10/2020                   LAFAYETTE          WI   PUBLIC

            MULTIPLE REPORTS OF DOWNED POWERLINES, TREE
            BRANCHES, AND A BLOWN TRANSFORMER AROUND
            ALICE ST. AND GALENA ST. ON THE SOUTH SIDE
            OF DARLINGTON. TIME ESTIMATED BASED ON
            RADAR.

0109 PM     TSTM WND DMG     2 W BELMONT             42.74N 90.38W
08/10/2020                   LAFAYETTE          WI   PUBLIC

            MULTIPLE REPORTS OF A SEMI TRUCK TIPPED OVER
            ON HWY 151 BETWEEN BELMONT AND PLATTEVILLE.
            TIME ESTIMATED BASED ON RADAR.

0525 PM     FLOOD            2 S OAK CREEK           42.85N 87.89W
08/10/2020                   MILWAUKEE          WI   TRAINED SPOTTER

            WATER OVER THE ROAD AT THE INTERSECTION OF
            ELM RD & NICHOLSON RD. IN OAK CREEK.

0513 PM     FLOOD            2 ESE OAK CREEK         42.87N 87.86W
08/10/2020                   MILWAUKEE          WI   PUBLIC

            WATER ACROSS ROADWAY. REPORT RELAYED VIA
            SOCIAL MEDIA.

0532 PM     HEAVY RAIN       1 NNW RACINE            42.75N 87.79W
08/10/2020  M3.00 INCH       RACINE             WI   COCORAHS

            3 INCHES OF RAIN IN JUST UNDER AN HOUR WITH
            STREET FLOODING.

0507 PM     FLOOD            2 W FRANKSVILLE         42.76N 87.95W
08/10/2020                   RACINE             WI   PUBLIC

            WATER OVER ROADWAY ON GOLF RD.

0507 PM     FLOOD            1 E FRANKSVILLE         42.76N 87.89W
08/10/2020                   RACINE             WI   PUBLIC

            CORRECTS PREVIOUS FLASH FLOOD REPORT FROM 1
            E FRANKSVILLE. FLOODING ON NORTHWESTERN AVE
            IN RACINE CTY.

0501 PM     FLOOD            4 W FRANKSVILLE         42.76N 87.98W
08/10/2020                   RACINE             WI   PUBLIC

            FLOODING OVER ROADWAY REPORTED AT 51ST ST
            AND 2 MILE ROAD IN RACINE CTY.

0500 PM     TSTM WND DMG     1 N ELMWOOD PARK        42.71N 87.82W
08/10/2020                   RACINE             WI   PUBLIC

            TREE REPORTED DOWN AT LOCATION.

0455 PM     TSTM WND DMG     RACINE                  42.73N 87.78W
08/10/2020                   RACINE             WI   PUBLIC

            REPORT RELAYED VIA SOCIAL MEDIA OF DOWNED
            TREE LIMBS CAUSED BY ESTIMATED 60 MPH GUSTS.

0455 PM     TSTM WND DMG     2 NNW ELMWOOD PARK      42.72N 87.84W
08/10/2020                   RACINE             WI   TRAINED SPOTTER

            LARGE TREE LIMBS DOWN AT LOCATION.

0448 PM     FLOOD            WATERFORD               42.76N 88.22W
08/10/2020                   RACINE             WI   PUBLIC

            FLOODING OVER INTERSECTION OF JEFFERSON ST.
            AND WASHINGTON ST. IN WATERFORD.

0421 PM     TSTM WND DMG     NORTH BAY               42.76N 87.78W
08/10/2020                   RACINE             WI   PUBLIC

            LARGE BRANCHES DOWN. REPORT RELAYED VIA
            SOCIAL MEDIA. TIME ESTIMATED FROM RADAR.

0415 PM     TSTM WND DMG     ELMWOOD PARK            42.69N 87.83W
08/10/2020                   RACINE             WI   PUBLIC

            LARGE TREE LIMBS DOWN AT LOCATION.

0413 PM     TSTM WND DMG     2 WNW ELMWOOD PARK      42.70N 87.86W
08/10/2020                   RACINE             WI   PUBLIC

            LARGE LIMBS DOWN AND DAMAGE TO SIDING.
            REPORT RELAYED VIA SOCIAL MEDIA. TIME
            ESTIMATED FROM RADAR.

0413 PM     TSTM WND DMG     1 SSW ELMWOOD PARK      42.68N 87.83W
08/10/2020                   RACINE             WI   PUBLIC

            TWO MATURE PINE TREES DOWN AROUND LATHROP
            AVE AND FOXWOOD RD IN MT. PLEASANT. TIME
            ESTIMATED BY RADAR.

0410 PM     TSTM WND DMG     UNION GROVE             42.68N 88.05W
08/10/2020                   RACINE             WI   LAW ENFORCEMENT

            SEVERAL REPORTS OF TREE DOWN IN UNION GROVE.
            TIME ESTIMATED BY RADAR.

0230 PM     TSTM WND DMG     4 W AVALON              42.63N 88.95W
08/10/2020                   ROCK               WI   PUBLIC

            TREE DOWN ACROSS ROAD AT LOCATION. REPORT
            RELAYED VIA PICTURE ON SOCIAL MEDIA. TIME
            ESTIMATED FROM RADAR.

0520 PM     FLOOD            1 NNE ELKHORN           42.68N 88.54W
08/10/2020                   WALWORTH           WI   PUBLIC

            STREET FLOODING ON 1ST AVE IN ELKHORN. VIDEO
            AND REPORT RELAYED VIA BROADCAST MEDIA.

0449 PM     HEAVY RAIN       1 N ELKHORN             42.69N 88.54W
08/10/2020  M3.90 INCH       WALWORTH           WI   PUBLIC

            3.9 RAINFALL MEASURED AS OF 4:49PM.
            ROADWAY FLOODING JUST WEST OF INTERSECTION
            OF HWY 67 AND HIDDEN TRAIL RD.

0400 PM     TSTM WND DMG     ELKHORN                 42.67N 88.54W
08/10/2020                   WALWORTH           WI   911 CALL CENTER

            NUMEROUS REPORTS OF TREES, TREE LIMBS, AND
            POWERLINES DOWN ACROSS WALWORTH COUNTY.

0355 PM     TSTM WND DMG     PELL LAKE               42.54N 88.35W
08/10/2020                   WALWORTH           WI   TRAINED SPOTTER

            REPORTS RELAYED VIA SOCIAL MEDIA OF
            POWERLINES AND LARGE TREE BRANCHES DOWN WITH
            ESTIMATED 70 MPH WINDS. TIME ESTIMATED BASED
            ON RADAR.

0338 PM     TSTM WND DMG     1 SSE LAKE GENEVA       42.57N 88.43W
08/10/2020                   WALWORTH           WI   PUBLIC

            MULTIPLE TREES DOWN ON LAKE GENEVA BLVD AND
            WEST SOUTH STREET. REPORT PASSED ALONG BY
            BROADCAST MEDIA. TIME ESTIMATED FROM RADAR.

0338 PM     TSTM WND DMG     LAKE GENEVA             42.59N 88.43W
08/10/2020                   WALWORTH           WI   911 CALL CENTER

            MULTIPLE REPORTS OF TREES AND TREE LIMBS
            DOWN IN THE CITY OF LAKE GENEVA. TIME
            ESTIMATED BASED ON RADAR.

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Hazardous Coastal Conditions for the Mid-Atlantic; Storm System Approaching Southern Alaska

Tornado and Wind Damage Across Far Southern Wisconsin on Monday, August 10th (Updated 2 PM 8/12)