Total Precipitation Percent of Mean
River Conditions 4/23
Average Temperature Departuer
Storm Reports 4/19

Midwest Weekly Highlights - April 17-23, 2011

Heavy Downpours Soak Most of the Midwest

The third week of April was wet for nearly all the region. Rainfall totals were two to five times normal in Illinois, Indiana, and Ohio, along with northern Kentucky and lower Michigan (Figure 1). Smaller pockets of below normal rainfall occurred in Minnesota, western Wisconsin, west central Missouri, and extreme southern Kentucky. More than 300 daily precipitation records were set. Precipitation total were over 3" for a big part of the Ohio River valley with amounts exceeding 4" in the Cincinnati, Ohio area (Figure 2). Stations in the Cincinnati area recorded up to 5.35" during the week. Runoff was considerable over saturated soils and numerous rivers in the Ohio basin were at or above flood stage and still rising (Figure 3). Flooding continued on the Red River in Minnesota but levels were dropping as the crests moved into Canada. Flood crests on the Mississippi River continued to move south and forecast crests are rising as the heavy precipitation in the southern Midwest further swells the Mississippi. Snow in the upper Midwest was as much as 6" above normal in northern Michigan (Figure 4).

Cooler Temperatures Push into Midwest

Much cooler temperatures pushed into the Midwest in the third week of April. Temperatures were below normal except Kentucky and extreme southern Indiana and Ohio. Departures were 2°F to 4°F above normal in eastern Kentucky and 11°F to 13°F below normal in Iowa and southwest Minnesota (Figure 5). Maximum temperatures were particularly depressed in that area, nearly 20°F below normal (Figure 6). Daily temperature records for the week were nearly all record low maximums. Maximum temperatures showed a tight transition from north to south, averaging in the 40s for the northern half of the region and in the 70s for southern Missouri and most of Kentucky (Figure 7).

Severe Weather Outbreak on April 19th

For the second time in April, the NWS Storm Prediction Center topped 1000 reports of severe weather on a single day. The outbreak on the 19th began in the early morning in Missouri and stretched across the southeastern half of the Midwest through the evening hours (Figure 8). Tornadoes were reported in Illinois (Christian, Macoupin, Montgomery, and Vermillion counties), Indiana (Cass, Clark, Dubois, Floyd, Grant, Harrison, Jay, Orange, Scott, Switzerland, and Washington counties), Kentucky (Boone, Breckinridge, Franklin, Oldham, Scott, and Simpson counties), Missouri (Bollinger, Cape Girardeau, New Madrid, Pemiscot, and Pike counties), and Ohio (Auglaize, Fairfield, Franklin, Licking, Mercer, Ottawa, Pickaway, Pike, and Van Wert counties). Most of the storms rated EF0 or EF1 but three EF2 storms were confirmed near Bretzville, Indiana (Dubois County), Celina, Ohio (Mercer County), and Granville, Ohio (Licking County).

Among more than 200 Midwest hail reports, were those of hail 2" or more in diameter in Missouri (Pike, Jefferson, St. Charles, Howell, Ozark, Osage, Douglas, Taney, Gasconade, and St. Louis counties) and Illinois (Greene, Calhoun, Monroe, and Peoria counties). Wind damage was widespread throughout the affected area with reported gusts of 80 to 90 mph and one report of 103 mph in southern Illinois (Jackson and Alexander counties). Gusts to 80 mph were also reported in Indiana and Ohio. Power outages affected at least 47,000 in Missouri, 83,000 in Illinois, and 55,000 in Ohio. Hundreds of flights were delayed at O'Hare Airport in Chicago (Cook County). Further north, from Iowa to Michigan, the storm was responsible for heavy wet snows measuring several inches including 9.9" in Green Bay, Wisconsin (Brown County).

More Severe Weather on the 22nd and 23rd

Severe weather struck again on the 22nd and 23rd of the month. Severe storms broke out along frontal boundaries across the southern extent of the region (Figure 9). Tornadoes were reported on the 22nd, mostly in the greater St. Louis area (Warren, Franklin, St. Charles, and St. Louis counties, Missouri and Clinton and Bond counties, Illinois). Stanley, Kentucky (Daviess County) also reported a twister on the 22nd. A few additional tornadoes were reported on the 23rd in Klondike, Illinois (Alexander County), Dexter, Missouri (Stoddard County), and near Knoxville, Kentucky (Pendleton County).

An EF4 tornado, the strongest in the metro area since 1967, moved across the north metro area hitting the St. Louis airport terminal. The resulting damage closed the facility to all flights for about 24 hours. Gradually outgoing and incoming flights resumed despite damage to the terminal and concourses. The C concourse will require months of repairs before it can be reopened. Travelers awaiting flights scrambled for cover as debris was sucked through the concourse.

Large hail fell in Illinois, Indiana, Kentucky, Ohio, Michigan, and Missouri. Hail reports were most numerous in Missouri with over 100 reports including some 4.00" to 4.50" reports from Montgomery County and Warren County. In the St. Louis area alone, more than 100 homes were destroyed and 2700 buildings were damaged by the storms but fortunately just minor injuries and no fatalities were reported.

Flash Flooding

The heavy rains across the southern half of the region caused widespread issues with flash flooding on the 19th and later in the week. On the 23rd, a man drowned in southwest Missouri (Ozark County) after he was washed out of his vehicle while attempting to drive through a low-water crossing. Others in Illinois, Indiana, and Kentucky had to be rescued from flood waters. Roads across the affected area, from Missouri to Ohio, are closed due to high water. In Illinois and Missouri, the governor called out the National Guard to help deal with flooding issues in the southern parts of each state.


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