As a large heat dome builds from the Great Lakes to the northeastern United States and southeastern Canada, rounds of heavy downpours will increase the risk of dangerous flash flooding from parts of the Plains to the Upper Midwest through early this week.
Inches of rain have already occurred within heavy downpours in a corridor from Kansas to Wisconsin. Significant ponding may occur on portions of major highways, segments of Interstates 35, 70, 80 and 90, causing blocked lanes and full stoppages in some areas.
Saturday night into Sunday morning, training heavy thunderstorms over the Milwaukee metro area produced significant flooding. Rainfall totals as of Sunday morning are in the 5-7 inch range, with more expected to come.
Rainfall rates will vary with each round but can reach 1 to 3 inches per hour at times, which is sufficient to trigger urban flooding in poorly drained areas and rapid rises on small streams.
Major cities potentially affected by flash flooding include:
•Kansas: Topeka
•Missouri: Kansas City
•Iowa: Des Moines, Davenport, Cedar Rapids, Dubuque
•Illinois: Moline
•Wisconsin: Madison, La Crosse
Three-day rainfall totals of 1 to 4 inches from Saturday to Monday are expected over a broad area from Kansas to the Upper Peninsula of Michigan. Within this zone, two separate regions of 4-to-8-inch rainfall is forecast with an AccuWeather Local StormMax™ of 14 inches, which will encompass far northeastern Kansas, eastern Iowa, southern Wisconsin and far northwestern Illinois.
Where rain has been limited in recent weeks, a reasonable amount of moisture will be welcomed as many crops, including corn, reach maturity. However, excessive rainfall during the event could lead to flooded fields and lost revenue.
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Severe weather risk to advance in central US
As cooler, less humid air advances southeastward from central Canada, thunderstorms will continue to erupt along the boundary between the cooler and hotter air masses.
On Sunday, severe weather brought some wind and hail reports to portions of Colorado and northern New Mexico into Kansas. Two tornadoes were also reported, one in northeastern Colorado and another in Iowa.
The risk for severe weather will continue on Monday across the Plains and Midwest. From eastern New Mexico to northern Missouri, any thunderstorm can bring flash flooding, hail and localized damaging wind gusts.
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