Flooding outlook for Illinois and surrounding states

April 22, 2013

By Alex Sosnowski
Expert Senior Meteorologist, AccuWeather.com

STATE COLLEGE, Pa. — AccuWeather reports additional rain will fall on flooded areas of the Midwest this week. However, there is some hope that the rain will not make the situation worse.

A storm bringing snow to part of the northern Plains, Rockies and upper Great Lakes during the first part of this week will send a swath of rain through the Midwest.

AccuWeather.com meteorologists expect this system to be less intense and faster-moving, when compared to last week’s storm that pushed rivers to moderate, major and record flood stage.

The new round of rain is projected to swing through from west to east, spanning into Wednesday.

Last week, portions of states from Missouri to Illinois, Iowa, Indiana, Michigan and Wisconsin received from 3 to 7 inches of rain. Much of that rain fell during a 24- to 36-hour period upon saturated ground.

While much of any additional rain that falls will also run off into streams and then progressively larger rivers, it would take more than the expected 1 to perhaps 2 inches of rain to fall to bring another round of flooding of equal magnitude on most rivers.

The rainfall is likely to slow the recession of river levels and could cause minor rises at some locations a short time after the rain.

Only if heavier rain than expected falls would there be another round of major to record flooding.

There is the likelihood for enough rainfall to create new flooding in poor drainage areas and along small streams.

Moving forward, there are indications of additional rainfall events through next week, but these are more likely to target areas farther to the south and east over the Central states.

States to watch for flooding problems moving forward through the end of April include Arkansas, Kentucky and Tennessee.

The speed, intensity and location of the heaviest rainfall with these systems will be monitored for the risk of stream and river flooding centered on Illinois and vicinity, as well as areas farther south and east in the Central states.

The National Weather Service issues official flood statements and river level forecasts based on their own rainfall projections and hydrological and geographical algorithms.

Dozens of barges broke free along the Mississippi River this weekend from St. Louis to Vicksburg, Miss. Increasing flow and rising water levels on the river were partially to blame.

Some of the barges have sunk and several near St. Louis drifted downstream and struck the Jefferson Barracks Bridge. While the bridge was closed for a time over the weekend, it has since been inspected and reopened. Most of the barges have been recovered or secured as of Monday.

Posted April 22, 2013

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