2008 Flooding

The first two weeks of June 2008 featured many days with rain and a few days with an exceptional amount of rain, across Southern Wisconsin. Between June 1st and June 14th, Madison recorded precipitation on 11 out of 14 days. In the same time span, Milwaukee recorded precipitation 10 out of 14 days. However, it was not the extended period of rainy weather that caused the flooding problems. Those problems were primarily due to two heavy rainfall events: the first on June 7th to June 8th and the second on June 12th. At many locations across Southern Wisconsin over 70% of the rainfall fell on those three days. The heavy rainfall produced flash flooding problems across Southern Wisconsin on several days, with severe river flooding experienced throughout the entire period. 

The image on the right shows rainfall totals across the Midwest with two regions of very heavy rainfall. The first is over much of Southern Wisconsin and the other is centered over Central Indiana. In both regions upwards of 12 to 16 inches of rainfall was reported.

The maps below show a more detailed map of rainfall over Wisconsin and show the heavy rainfall axis centered over Southern Wisconsin. These represent rainfall totals across Southern Wisconsin during the first two weeks in June, which ranged between 6 to 12 inches for much of the area. There was an isolated corridor of 12 to 16 inches of rain from Northern Sauk County into Northwest Dodge County.

• On June 7th, 4.93" of rain broke the old record rainfall for the date which was 2.44" (June 7, 1916).
• On June 8th, 2.25" of rain broke the old record rainfall for the date which was 1.24" (June 8, 1974).
• Combined, these two days of rainfall broke the 48-hour all time rainfall record at Milwaukee. The previous record was 6.84", which was recorded on August 5-6, 1986.
• On June 7-8, 2008, Milwaukee measured 7.18" of rain!
• There was also a 24-hour period stretching from June 7th to June 8th where Milwaukee recorded a 24-hour precipitation total of 5.70". This was the 3rd highest 24-hour precipitation total at Milwaukee ever.
• Officially, Milwaukee observed 12.27" of rain for the month of June. This easily broke the record for highest June rainfall total. The previous record was 10.13", set in 1917.
• The 10.13" of rain in June 1917 was also the record for the highest rainfall total in any month at Milwaukee all time.
• Therefore, the 12.27" of rainfall observed during this period in 2008 sets a new record for maximum monthly rainfall all-time for Milwaukee. 

• On June 7th, 2.23" of rain broke the old record rainfall for the date which was 2.01" (June 7, 1993).
• On June 8th, 4.11" of rain broke the old record rainfall for the date which was 1.40" (June 8, 1874).
• On June 12th, 2.57" of rain broke the old record rainfall for the date which was 1.20" (June 8, 1877).
• Officially, Madison observed 10.93" of rain for the month of June. This easily broke the record for highest June rainfall total. The previous record was 9.95", set in 1978.
• The 10.93" of rain in June 2008 also placed 2nd on the list of record highest rainfall totals in any month at Madison all time, tied with the 10.93" of rain that fell in July of 1950.
• The record monthly rainfall all-time is 15.18" of rain, set in August of 2007.
• There was also a 24-hour period stretching from June 7th to June 8th where Madison recorded a 24-hour precipitation total of 5.27". This was the 2nd highest 24-hour precipitation total at Madison, and only 0.04" behind the record of 5.31", set on September 7-8, 1941.

The amount of rainfall over the first half of June put Southern Wisconsin well above normal precipitation totals for that time of year. In fact precipitation for much of the spring and into June was well above normal. According to the MRCC graphic above, precipitation amounts from June 1st to June 19th were over 400% of normal values across portions of Southern Wisconsin. In fact, the most anomalously high precipitation values were observed over Southern Wisconsin. The exceptional amount of rainfall in a short period of time allowed for widespread flooding issues to develop. 

Flash flooding was especially a problem on June 7th and June 8th, when a large portion of the total rainfall during the first two weeks of June 2008 fell. Flash flooding was reported as early as 2:43 PM on June 7th when water was reported to be over Interstate-39 where it met Highway 78 in Columbia County. After that, numerous reports of flash flooding were received from across Southern Wisconsin, and then Waukesha County and into the Milwaukee Metro area.

On June 7th, numerous road washouts were reported in Sauk and Columbia Counties. A few bridges were washed away in Sauk County around Reedsburg and La Valle. In Waukesha and Milwaukee Counties, vehicles were stalling and floating in water at some intersections and in some parking lots. Manhole covers were being blown off from water pressure, and a few roads were also washing out. Just west of Downtown Milwaukee, around 2 feet of water was reported, causing damage to buildings and cars were floating in intersections. Some people in Milwaukee County had to abandon their vehicles and swim to safety. At one point, a section of Interstate-894 had to be closed near 27th street due to water over the freeway and on/off ramps. Mitchell International Airport was closed at 8 PM due to major flooding, and the contract observer there reported waist deep water flowing into their building. Also, a state of emergency was declared in Milwaukee due to extensive flooding. 

Outside of those four counties, sporadic reports of flash flooding were received on June 7th. Notably, a spotter 4 miles north-northeast of Sun Prairie (Dane County) received 1.65" of rain in 20 minutes, and then later received another 0.40" of rain in 10 minutes. These extremely heavy rainfall rates were probably typical of what was being observed elsewhere around the area, given the extremely moist air mass in place across the region. 

On June 8th, yet another round of heavy rainfall only exacerbated flooding problems by producing more episodes of flash flooding across Southern Wisconsin. Many road closures and washouts were reported from numerous counties. The Kilbourn Tunnel in Milwaukee had to be closed due to the flash flooding. 

On June 12th, another round of heavy rainfall caused flash flooding issues, but this time in some areas that had not previously reported severe flash flooding. Fond du Lac County was hit particularly hard. Most city roads in Fond du Lac were reported to be underwater. The Fond du Lac River was over bridges in some places. In Ripon, over half the roads were closed due to flash flooding. Between 3 to 4 feet of standing water was observed over portions of the southern half of the city. In Columbia County, Interstate 90/94 was closed between mile markers 92 and 106, and numerous roads were washed out across the county. In Dodge County, some residences in the Beaver Dam area had about 2 feet of water surrounding homes. 

Numerous area rivers hit record levels during the major flooding event in the early half of June 2008. In total 25 river points reached record high levels marks. That represents over half of the 43 river gauges in the NWS Milwaukee/Sullivan hydrologic service area. Most of those that did not reach record levels had crests in the top 5 all time. Some of the data is missing, due to damage to the gauges, communications, and/or loss of power. Therefore, some of these crests may have been higher than the data suggests. 

The Cooperative Institute for Meteorological Satellite Studies (CIMSS) at the University of Wisconsin Madison developed a comparison of satellite images before and after the flooding. These images are displayed on the right and viewed from their blog on the topic. 

One significant advancement in our ability to analyze, detect, and take action on signficant rainfall events was the development of the Flooded Locations And Simulated Hydrographs Project (FLASH). This project was launched in early 2012 largely in response to the demonstaration and real-time availability of high-resolution, accurate rainfall observations for the  MRMS/Q3 project . FLASH introduces a new paradigm in flash flood precidtions that uses the MRMS forcing and produces flash flood forecasts at 1-km/5-minute resolution. The primary goal of the FLASH project is to improve the accuracy, timing, and specificity of flash flood warnings in the US, thus saving lives and protecting infrastructure. 

In the past all Flash Flood Warnings would trigger an alert on the Wireless Emergency Alert (WEA) system. Public perception was that the NWS over-alerts for FFWs, and the Federal Emergency Management Agency (FEMA) noted a large number of complaints about overnight WEA alerts for FFWs with perceived little impact.

So, starting in 2020, the NWS updated the format of Flash Flood Warnings to improve the public response to FFWs by providing easily readable information and issuing WEA alerts only for flash flood events that require immediate life-saving action.