Storm Record · Dane, Dodge, Jefferson, Sauk, Walworth, Waukesha Counties
May 22, 2011: Hail across six counties
What the National Weather Service recorded
A deep 500 mb low and associated surface low pressure tracked from eastern South Dakota into central Minnesota, lifting a warm front into Wisconsin during the early afternoon of May 22nd. Cool 500 mb temperatures and moist surface dew points in the lower 60s produced sufficient instability for thunderstorm development, with mean-layer CAPE of 2000 to 2500 J/KG. A mid-level jet streak of 50-60 knots produced 40-50 knots of deep-layer wind shear for supercell thunderstorm development, with low-level shear of 30 to 40 knots in the 0-1 km layer as a low-level jet strengthened enhancing the tornado potential, especially near the warm front.
Source: NOAA Storm Events Database · episode 52729
Every report, in the Weather Service's words
Where It Hit
| Location | County | Hazard | Size | Report |
|---|---|---|---|---|
| Hustisford | Dodge | Wind | 69 mph wind | Numerous trees and power lines were reported blown down by damaging thunderstorm wind gusts in the Hustisford area. A tree fell on a home damaging the roof. A tree fell on an occupied car, and the driver injured his shoulder (indirectly-related) exiting the car. Total damage in the area amounted to $10,000. |
| Watertown (2 S) | Jefferson | Wind | 64 mph wind | Numerous trees and power lines were reported blown down by damaging thunderstorm wind gusts estimated at 56 knots in a swath from 2 miles south of Watertown to Watertown. A tree fell on a home, with minimal damage reported by firefighters responding to the scene. The winds blew over a shed that damaged fencing, a viewing platform and a horse trailer at the Avalon Therapeutic Equestrian Center. Damage in the area totaled $50,000 dollars. |
| Lyons | Walworth | Wind | 64 mph wind | A severe thunderstorm produced damaging wind gusts that downed trees in the town of Lyons, including a large maple tree that was estimated to be 235 years old, the oldest tree in Walworth County. |
| Hustisford | Dodge | Wind | 64 mph wind | A second round of severe thunderstorms affected Hustisford with damaging winds. This round downed trees that damaged a fence and did $500 worth of damage to a house. |
| Whitewater | Walworth | Wind | 60 mph wind | A trained spotter reported severe thunderstorm wind gusts that downed trees and tree limbs in Whitewater. |
| Elkhorn (2 S) | Walworth | Wind | 60 mph wind | A severe thunderstorm produced wind gusts that downed power lines, trees and tree limbs just south of Elkhorn. The downed trees and limbs damaged a few homes as well as a fence. |
| Ft Atkinson | Jefferson | Wind | 58 mph wind | Trees and power lines were reported blown down by damaging thunderstorm wind gusts measured at 50 knots (58 mph) in a swath from Ft. Atkinson to Jefferson. |
| Watertown (2 SW) | Jefferson | Hail | 1.75" hail | |
| Sun Prairie (2 W) | Dane | Hail | 1.75" hail | Ham radio operators reported severe thunderstorms dropped hail up to 1.75 inches in diameter in a 4-mile wide swath from 2 miles west of Sun Prairie to around 4 miles south-southwest of Columbus. |
| Richmond | Walworth | Hail | 1.75" hail | |
| Eagle (4.27 SW) | Waukesha | Hail | 1.75" hail | A severe thunderstorm produced hail up to 1.75 inches in diameter in a 4-mile wide swath from the southwest corner of Waukesha County northeast to North Prairie. |
| Whitewater (8 S) | Walworth | Hail | 1.25" hail | |
| Oak Hill (3.66 NE) | Jefferson | Hail | 1.25" hail | |
| Clyman (1 N) | Dodge | Hail | 1" hail | |
| Lake Mills (3 SW) | Jefferson | Hail | 1" hail | Ham radio operators reported severe thunderstorms dropped hail up to 1.00 inch in diameter in a 3-mile wide swath from 3 miles southwest of Lake Mills to 1 mile northeast of Lake Mills. |
| (msn)truax Fld Madis (2 E) | Dane | Hail | 0.75" hail | |
| Reedsburg (2 S) | Sauk | Hail | 0.75" hail |
Service areas this storm touched