There’s been no shortage of rain this June in Western Wisconsin. Through June 27th, there have been only 9 days of totally rain-free weather in Eau Claire. It’s been even worse in La Crosse, where only 6 days have been completely dry.
Some of the rain events this month have been intense with torrential downpours, severe weather, and flooding. This past weekend saw the worst of the flooding for some of our southern counties. Below is a look at the 3-day rainfall totals ending at 7 AM on June 23rd. This graphic is from the La Crosse National Weather Service office. Areas of Crawford County along the Mississippi River saw over 7” of rain. In parts of Houston County in Minnesota, over 9” of rain fell. These are just incredible numbers! This is a lot of rain in a relatively short amount of time. Not surprisingly, these rain totals lead to bad flooding throughout this area. Several counties were declared disaster areas. Millions of dollars in damage were done due to the flooding.
In the middle of the last week of June, the flooding shifted north into the Eau Claire area. A slow moving cluster of thunderstorms dropped between 1-3” of rain across some parts of Western Wisconsin. Flash flooding occurred in River Falls, Menomonie, Eau Claire, Lake Hallie, Altoona, and up into Chippewa Falls. Here at the station we picked up 1.81” of rain in little more than an hour and a half. With how wet it has been this month that was too much for storm drains to handle. Many roads had standing water. One road was washed away up in Lake Hallie. On Highway 53, a mudslide just outside Eau Claire brought traffic to a snail’s pace for some time that Wednesday evening.
So how did these storms create that much of a mess? Well first of all, we were already predisposed to flooding. We’ve had a lot of rain this month in the Eau Claire area, and the ground is fairly saturated. So if you can get a lot of rain in a short amount of time, flooding was a good bet. That's just what happened.
The graphic below shows the set up for June 26th. It was a warm and very humid day. Dewpoints were in the low 70s for much of the day. It definitely had that tropical feel in the air. With enough sunshine during the day, the storms that fired out ahead of a frontal boundary were in an environment with a ton of instability and moisture. Those storms were able to tap into all that moisture and instability to produce such torrential downpours with rainfall rates of 2-3” per hour.
The reason the flooding was so bad though in the Eau Claire area was because of the winds higher up in the atmosphere. The winds up there were fairly week and are responsible for moving the thunderstorms along. Those lighter winds meant that the storms would move fairly slowly. They made for very efficient rain producers. The gone news is we look to dry things out a bit heading into July. We definitely all could use a break from the rain.