Flooding and Hail in Wisconsin, July 20, 1999

Name: Flooding and Hail in Wisconsin, July 20, 1999
Start: 1999-07-20T13:20
End: 1999-07-20T23:20
Location: Wisconsin

July 20, 1999 · NWS MKX · 11 events in 7 counties and zones

Where it happened

Every event with a place to put it; 5 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: 0
Property damage: $966,000
Crop damage: $100,000
Events: 11

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.

Thunderstorms packing destructive winds, large hail, heavy rainfall, and lightning strikes pummelled southern Wisconsin in the afternoon and nightime hours. The extreme southeast corner of Iowa County just west and north of Blanchardville experienced damaging winds. Three farms had significant damage. Altogether, 2 barns were destroyed, and one damaged. In addition, a corn crib, machine shed, and mechanical equipment were damaged. One of the farm's home sustained extensive damage after a large tree crashed through it. Eight calves were crushed in one of the destroyed barns, along with some hay crop. About 150 large trees were flattened. The severe storms continued southeast through Green county in the afternoon. About 100 livestock injuries/deaths occurred in Green County when 3 barns were destroyed by the powerful winds near Albany and a family of 3 were trapped in their vehicle due to fallen power line poles. 1.15 inches of rain fell in 15 minutes near New Glarus. The heavy rains resulted in urban/small stream flooding in and around Monticello (Green Co.). Water levels on some roads reach 6 to 12 inches. In neighbouring Lafayette county three-quarter inch hail was observed at Blanchardville and in southwest Rock county 3 farms sustained extensive damage to several buildings. A barn was downed west of Beloit and a few corn fields were flattened. Lightning struck a residential home in Rock county, destroying the garage and contents and causing heat/smoke damage to the home. After sunset lightning caused an attic fire near Baraboo in Sauk county and wind downed numerous trees near Beaver Dam in Dodge county, damaging the roofs of 6 homes. Lightning struck two buildings in West Allis (Waukesha Co.): a Fire Department building sustained communications and computer equipment damage; and a residential home had considerable fire damage to it roof/attic and 2nd story. In all, 10,000 customers were without power in southcentral and southeast Wisconsin due to the wind or lightning damaging power lines.

The radar

The Milwaukee radar (KMKX), 113 km away, was scanning. The volume nearest the first event began at 19:18 UTC.

Open the radar archive at this moment

Event by event

5 thunderstorm wind, 3 lightning, 2 flood, 1 hail. Local standard time, as filed.

Thunderstorm Wind, Iowa

When: July 20, 1:20 PM CST
Where: Iowa County, Blanchardville to 4 mi N of Blanchardville
Property damage: $300,000
Crop damage: $50,000
Reported by: NEWSPAPER
Coordinates: 42.830, -89.930

Hail, Lafayette

When: July 20, 1:34 PM CST
Where: Lafayette County, 2 mi N of Argyle
Measured: 0.75 in hail
Reported by: NEWSPAPER
Coordinates: 42.730, -89.870

Thunderstorm Wind, Green

When: July 20, 1:40 PM CST
Where: Green County, 4 mi WNW of New Glarus
Property damage: $3,000
Reported by: NEWSPAPER
Coordinates: 42.830, -89.700

Flood, Green

When: July 20, 1:45 PM CST to 4:00 PM CST
Where: Green County, 2 mi S of Monticello
Reported by: NEWSPAPER
Coordinates: 42.680, -89.602 (the zone’s center; the record gives no point)

Thunderstorm Wind, Green

When: July 20, 1:55 PM CST to 2:05 PM CST
Where: Green County, Albany to 1 mi S of Albany
Property damage: $225,000
Reported by: LAW ENFORCEMENT
Coordinates: 42.700, -89.450

Lightning, Rock

When: July 20, 2:13 PM CST
Where: Rock County, 2 mi SE of Janesville
Property damage: $35,000
Reported by: NEWSPAPER
Coordinates: 42.671, -89.072 (the zone’s center; the record gives no point)

Thunderstorm Wind, Rock

When: July 20, 2:25 PM CST to 2:40 PM CST
Where: Rock County, Orfordville to 2 mi W of Beloit
Property damage: $300,000
Crop damage: $50,000
Reported by: EMERGENCY MANAGER
Coordinates: 42.620, -89.280

Flood, Rock

When: July 20, 2:30 PM CST to 4:00 PM CST
Where: Rock County, Beloit
Reported by: NEWSPAPER
Coordinates: 42.671, -89.072 (the zone’s center; the record gives no point)

Thunderstorm Wind, Dodge

When: July 20, 9:30 PM CST
Where: Dodge County, Beaver Dam
Property damage: $20,000
Reported by: NEWSPAPER
Coordinates: 43.470, -88.830

Lightning, Sauk

When: July 20, 10:35 PM CST
Where: Sauk County, 3 mi SW of Baraboo
Property damage: $8,000
Reported by: NEWSPAPER
Coordinates: 43.427, -89.948 (the zone’s center; the record gives no point)

Lightning, Milwaukee

When: July 20, 11:20 PM CST
Where: Milwaukee County, West Allis
Property damage: $75,000
Reported by: NEWSPAPER
Coordinates: 43.022, -87.929 (the zone’s center; the record gives no point)

What these are

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.
Flood: Flooding that develops more slowly than a flash flood: rivers leaving their banks, or water standing over land for an extended time.
Lightning: A lightning strike that killed, injured or caused damage.

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

The same day elsewhere

Every storm in Wisconsin in 1999 Every state in 1999 This day in weather history Warnings in Wisconsin, July 1999

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: 5711362, 5711354, 5711353, 5711361, 5711352, 5711359, 5711355, 5711356, 5711357, 5711358, 5711360.