Hydroclimatology of the 2008 Midwest floods

Abstract

The late spring/early summer flooding that occurred in the American Midwest between May and June 2008 resulted from a combination of large‐scale atmospheric circulation patterns that supported a steady influx of moisture into the area. A low pressure system centered over the central‐western United States steered a strong jet and associated storms along its eastern edge from the west to southwest and an anomalously strong Great Plains Low Level Jet brought continuous warm and moist air into the area from the Gulf of Mexico into the area. We examine and quantify here the impact these circulation patterns had on the hydroclimatology of the Midwest highlighting the magnitude, frequency, geographic distribution, and temporal evolution of precipitation that ultimately magnified the flooding. Historical precipitation records were used to assess the regional rainfall characteristics at various geographic and time scales. Five distinct hydroclimatic characteristics contributed to the definition of the 2008 flood including persistent high surface soil moisture conditions prior to flooding exasperated by anomalously high rainfall, extreme rainfall totals covering extensive areas, increased frequency of shorter‐term, smaller‐magnitude events, persistent multiday heavy precipitation events, and extreme flood‐producing rain storms. The major flooding lasted for approximately 24 days and most greatly impacted the state of Iowa, southern Wisconsin, and central Indiana. Its occurrence during the May–June period makes the event especially unusual for this region.

High-resolution projections of climate-related risks for the Midwestern USA

“…Heavy rainfall over parts of the Midwest (e.g. nearly 50% of mean annual total accumulation in eastern Iowa fell between 21 May and 13 June 2008) resulted in major flooding lasting over 24 d in early summer 2008 over parts of Iowa, southern Wisconsin and central Indiana, and caused total economic losses of $15 billion (including $8 billion in agricultural losses) (Budikova et al 2010). These floods also caused major transportation disruptions, including $154 million of losses to Illinois railroads (Changnon 2009).…”

Remote sensing-based characterization of rainfall during atmospheric rivers over the central United States

“…Lavers and Villarini (2013) showed that more than 60% of the annual maximum floods during 1979-2011 period were associated with ARs over much of the central United States, with seven out of the ten largest floods associated with these storms. Moreover, ARs are the mechanisms responsible for some of the most devastating flooding events over this region in recent decades, including the floods of July 1993 (Dirmeyer and Kinter, 2009), June 2008 floods over eastern Iowa (Budikova et al, 2010;Smith et al, 2013), May 2010 flood in Nashville (Tennessee) and surrounding areas (Moore et al, 2012), and the flood of April 2013 over Chicago and eastern Iowa (Campos and Wang, 2015;Nayak et al, 2016).…”

On the skill of numerical weather prediction models to forecast atmospheric rivers over the central United States

“…They found that the upper tail of the annual flood peak distribution over a large portion of the central United States is largely controlled by AR events. They further noted that over the period of the study (1979–2011), the two most destructive flood events over the central United States—the great flood of 1993 [ Kunkel et al , ] and the June 2008 flood in the Midwest [ Dirmeyer and Kinter , ; Budikova et al , ; Smith et al , ], both causing the loss of billions of U.S. dollars and claiming 48 and 24 lives (http://www.ncdc.noaa.gov/billions/), respectively—were preceded and accompanied by ARs.…”