Wisconsin, 1998

Flooding and Hail in Wisconsin, July 20, 1998

July 20, 1998 · NWS MKX · 31 events in 16 counties and zones

Frontal induced severe thunderstorms downed trees and power lines over much of south-central and southeast Wisconsin during the evening hours. ) area where downburst winds leveled hundreds of large trees, several street signs, and a large quantity of commercial signs.

Where it happened

Every event with a place to put it; 9 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

  • Tornadoes
  • Tropical storms and surge
  • Floods
  • Wind
  • Hail
  • Winter weather
  • Heat and drought
  • Cold
  • Fire, smoke and dust
  • Marine and coastal
  • Other

Open the live radar over this ground

The toll

Deaths
0
Injuries
3
Property damage
$2.0 million
Crop damage
None recorded
Events
31

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS MKX wrote it up.

Frontal induced severe thunderstorms downed trees and power lines over much of south-central and southeast Wisconsin during the evening hours. Hardest hit was the Lake Geneva (Walworth Co.) area where downburst winds leveled hundreds of large trees, several street signs, and a large quantity of commercial signs. A dozen vehicles were damaged or totaled and 2 homes sustained significant damage. A 100 mph wind was recorded at the Grand Geneva Airport and 2 people were injured (one in a moving vehicle). Local officials consider this to be the worst storm in 58 years. In Monroe (Green Co.), the powerful thunderstorm winds also damaged 6 vehicles and 2 homes. Elsewhere, hail, high winds, lightning, and torrential rains played havoc. In West Bend (Washington Co.), lightning ignited a fire in an apartment complex and caused a quarter of a million dollars in damage. Urban flooding in Janesville (Rock Co.) resulted in standing water between a foot to a foot and a half deep across area roadways. Wind damage was the most common culprit though with over 200 power lines downed and 17,000 customers without service in southeast Wisconsin and 10,000 residents left without power across south-central Wisconsin.

The radar

The Milwaukee radar (KMKX), 66 km away, was scanning. The volume nearest the first event began at 22:38 UTC.

Open the radar archive at this moment

Event by event

19 thunderstorm wind, 7 lightning, 3 hail, 2 flood. Local standard time, as filed.

Lightning, Racine

When
July 20, 3:52 PM CST
Where
Racine County, Union Grove
Property damage
$2,000
Reported by
NEWSPAPER
Coordinates
42.730, -87.812 (the zone’s center; the record gives no point)

Flood, Dodge

When
July 20, 4:15 PM CST to 5:30 PM CST
Where
Dodge County, Randolph
Reported by
AMATEUR RADIO
Coordinates
43.416, -88.707 (the zone’s center; the record gives no point)

Thunderstorm Wind, Sauk

When
July 20, 4:40 PM CST
Where
Sauk County, Plain
Property damage
$2,000
Reported by
AMATEUR RADIO
Coordinates
43.280, -90.050

Thunderstorm Wind, Jefferson

When
July 20, 5:07 PM CST
Where
Jefferson County, Waterloo
Property damage
$1,000
Reported by
LAW ENFORCEMENT
Coordinates
43.180, -88.980

Thunderstorm Wind, Sauk

When
July 20, 5:10 PM CST
Where
Sauk County, Lake Delton to 3 mi of Lake Delton
Property damage
$2,000
Reported by
TRAINED SPOTTER
Coordinates
43.580, -89.850

Thunderstorm Wind, Lafayette

When
July 20, 5:10 PM CST
Where
Lafayette County, 5 mi N of Argyle
Property damage
$2,000
Reported by
TRAINED SPOTTER
Coordinates
42.770, -89.870

Thunderstorm Wind, Lafayette

When
July 20, 5:15 PM CST
Where
Lafayette County, South Wayne
Property damage
$4,000
Reported by
LAW ENFORCEMENT
Coordinates
42.570, -89.880

Thunderstorm Wind, Columbia

When
July 20, 5:15 PM CST
Where
Columbia County, Poynette
Property damage
$3,000
Reported by
LAW ENFORCEMENT
Coordinates
43.400, -89.400

Lightning, Washington

When
July 20, 5:15 PM CST
Where
Washington County, West Bend
Property damage
$262,000
Reported by
NEWSPAPER
Coordinates
43.369, -88.231 (the zone’s center; the record gives no point)

Hail, Jefferson

When
July 20, 5:20 PM CST
Where
Jefferson County, Johnson Creek
Measured
0.75 in hail
Reported by
LAW ENFORCEMENT
Coordinates
43.080, -88.770

Thunderstorm Wind, Green

When
July 20, 5:20 PM CST
Where
Green County, Monroe
Property damage
$50,000
Reported by
EMERGENCY MANAGER
Coordinates
42.600, -89.630

Hail, Dane

When
July 20, 5:23 PM CST
Where
Dane County, Oregon
Measured
1 in hail
Reported by
LAW ENFORCEMENT
Coordinates
42.930, -89.380

Thunderstorm Wind, Dane

When
July 20, 5:50 PM CST
Where
Dane County, Belleville
Property damage
$2,000
Reported by
LAW ENFORCEMENT
Coordinates
42.850, -89.530

Thunderstorm Wind, Jefferson

When
July 20, 5:53 PM CST
Where
Jefferson County, Ixonia
Property damage
$5,000
Reported by
LAW ENFORCEMENT
Coordinates
43.150, -88.600

Thunderstorm Wind, Rock

When
July 20, 5:55 PM CST
Where
Rock County, Clinton
Measured
63 kt (72 mph)
Reported by
TRAINED SPOTTER
Coordinates
42.570, -88.870

Lightning, Rock

When
July 20, 5:56 PM CST
Where
Rock County, Janesville
Property damage
$50,000
Reported by
NEWSPAPER
Coordinates
42.671, -89.072 (the zone’s center; the record gives no point)

Thunderstorm Wind, Rock

When
July 20, 5:58 PM CST
Where
Rock County, Janesville to Milton
Measured
60 kt (69 mph)
Property damage
$100,000
Reported by
AMATEUR RADIO
Coordinates
42.680, -89.020

Flood, Rock

When
July 20, 6:00 PM CST to 7:00 PM CST
Where
Rock County, Janesville
Reported by
EMERGENCY MANAGER
Coordinates
42.671, -89.072 (the zone’s center; the record gives no point)

Lightning, Waukesha

When
July 20, 6:00 PM CST
Where
Waukesha County, Oconomowoc
Property damage
$4,000
Reported by
NEWSPAPER
Coordinates
43.018, -88.304 (the zone’s center; the record gives no point)

Thunderstorm Wind, Walworth

When
July 20, 6:03 PM CST
Where
Walworth County, Delavan
Measured
52 kt (60 mph)
Property damage
$2,000
Reported by
AMATEUR RADIO
Coordinates
42.630, -88.630

Thunderstorm Wind, Milwaukee

When
July 20, 6:10 PM CST
Where
Milwaukee County, Milwaukee
Injuries
1 direct, 0 indirect
Property damage
$1,000
Reported by
EMERGENCY MANAGER
Coordinates
43.030, -87.970

Thunderstorm Wind, Walworth

When
July 20, 6:15 PM CST
Where
Walworth County, Lake Geneva
Measured
87 kt (100 mph)
Injuries
2 direct, 0 indirect
Property damage
$1.5 million
Reported by
EMERGENCY MANAGER
Coordinates
42.600, -88.430

Thunderstorm Wind, Racine

When
July 20, 6:20 PM CST
Where
Racine County, Burlington
Property damage
$3,000
Reported by
NEWSPAPER
Coordinates
42.670, -88.270

Lightning, Dane

When
July 20, 6:43 PM CST
Where
Dane County, Deerfield
Property damage
$1,000
Reported by
NEWSPAPER
Coordinates
43.067, -89.418 (the zone’s center; the record gives no point)

Thunderstorm Wind, Kenosha

When
July 20, 6:45 PM CST
Where
Kenosha County, Silver Lake
Property damage
$5,000
Reported by
LAW ENFORCEMENT
Coordinates
42.550, -88.170

Thunderstorm Wind, Fond du Lac

When
July 20, 10:05 PM CST
Where
Fond du Lac County, Ripon to Waupun
Property damage
$10,000
Reported by
LAW ENFORCEMENT
Coordinates
43.830, -88.830

Thunderstorm Wind, Dodge

When
July 20, 10:47 PM CST
Where
Dodge County, Theresa
Measured
54 kt (62 mph)
Property damage
$2,000
Reported by
AMATEUR RADIO
Coordinates
43.520, -88.450

Thunderstorm Wind, Washington

When
July 20, 11:02 PM CST to 11:10 PM CST
Where
Washington County, Slinger
Measured
52 kt (60 mph)
Property damage
$10,000
Reported by
TRAINED SPOTTER
Coordinates
43.330, -88.280

Hail, Ozaukee

When
July 20, 11:40 PM CST
Where
Ozaukee County, 3 mi SW of Port Washington
Measured
0.75 in hail
Reported by
LAW ENFORCEMENT
Coordinates
43.350, -87.920

Lightning, Ozaukee

When
July 20, 11:45 PM CST
Where
Ozaukee County, Grafton
Property damage
$10,000
Reported by
EMERGENCY MANAGER
Coordinates
43.403, -87.891 (the zone’s center; the record gives no point)

Lightning, Ozaukee

When
July 20, 11:51 PM CST
Where
Ozaukee County, 3 mi SW of Port Washington
Property damage
$8,000
Reported by
EMERGENCY MANAGER
Coordinates
43.403, -87.891 (the zone’s center; the record gives no point)

What these are

Lightning
A lightning strike that killed, injured or caused damage.
Flood
Flooding that develops more slowly than a flash flood: rivers leaving their banks, or water standing over land for an extended time.
Thunderstorm Wind
Winds from a thunderstorm of 50 knots (58 mph) or more, or lower winds that caused damage or casualties. Measured gusts are marked MG, estimated EG.
Hail
Hail three-quarters of an inch or larger, or smaller hail that caused damage, filed with the largest stone measured.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

More

Every storm in Wisconsin in 1998Every state in 1998This day in weather historyWarnings in Wisconsin, July 1998

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 5662371, 5662363, 5662348, 5662355, 5662349, 5662350, 5662351, 5662362, 5662447, 5662356, 5662544, 5662352, 5662353, 5662357, 5662360, 5662365, 5662359, 5662361, 5662364, 5662367, 5662366, 5662370, 5662368, 5662354, 5662369, 5662545, 5662372, 5662540, 5662541, 5662542, 5662543.