Storm Record · Dane, Dodge, Jefferson, Walworth, Waukesha Counties
June 18, 2009: Straight-line wind across five counties
What the National Weather Service recorded
A warm front set up across far southern Wisconsin on the afternoon of June 18th as an upper level disturbance moved eastward into the Upper Midwest. A line of severe thunderstorms formed in an area of very warm, unstable air and moved through south-central and southeast Wisconsin overnight. With surface dewpoints near 70, MLCAPE values near 3000 J/kg, and strong wind shear, the storms produced damaging winds, large hail up to 2.75 inches in diameter, dangerous lightning, and a weak tornado. These thunderstorms also dumped very heavy rain up to 4 inches over a relatively short period of time, causing numerous reports of flash flooding across Dane, Waukesha, and Milwaukee counties. At the height of the storms, about 27,000 households were without electricity in southeastern Wisconsin due to damaged power-lines.
Source: NOAA Storm Events Database · episode 30205
Every report, in the Weather Service's words
Where It Hit
| Location | County | Hazard | Size | Report |
|---|---|---|---|---|
| Middleton | Dane | Wind | 64 mph wind | Seveal large trees blown down by thunderstorm winds. |
| Iron Ridge (2 WSW) | Dodge | Wind | 64 mph wind | Several large trees were blown down from thunderstorm winds. One road was blocked by tree debris. |
| Ft Atkinson (4 ENE) | Jefferson | Wind | 64 mph wind | A few large trees were toppled and power-line were down due to tree debris. |
| Downtown Waukesha (3 SW) | Waukesha | Wind | 64 mph wind | Several large trees were toppled and a couple power-lines sustained damage due to tree debris. |
| Millard | Walworth | Wind | 64 mph wind | A few large trees were blown down by thunderstorm winds. |
| Dane | Dane | Hail | 2.75" hail | Hail increased from 1.75 at 22:23 to 2.75 at 22:25. |
Service areas this storm touched