Midwest Weekly Highlights - June 22-30, 2010

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Wet End to June

The last nine days of June saw rainfall totals more than twice normal across a large area that included most of Iowa and Wisconsin. Southern Minnesota, northern Illinois, central Indiana, Upper Michigan, and western Lower Michigan were also more than double normal for the period (Figure 1) as precipitation totals of 2.5 to 6 inches were widespread (Figure 2). The heavy rain in the Upper Midwest helped ease drought, though multi-year deficits remain (Figure 3). Daily precipitation records were again numerous but tapered off at the end of the month.
 

Near Normal Temperatures

Temperatures were within a couple degrees of normal for the northern two-thirds of the region. The southern third of the region was 2°F to 5°F above normal (Figure 4). Cooler weather the last couple days of the month offset warmer days earlier in the period and brought drier air and a break from the heavy rains and severe weather. 
 

Severe Weather Continues

Severe weather continued its grip on the Midwest. Severe storms were again widespread (Figure 5) during the last nine days of the month. Severe weather on the 22nd and 23rd, stretched from northern Iowa to northern Ohio. Twisters were reported in Iowa, Wisconsin, Illinois, Indiana, and Michigan. Hundreds of reports of damage from thunderstorm winds were also amassed, including semis blown off Interstate 35.

An EF4 tornado struck near Sibley, Iowa (Osceola County) on the night of the 25th. The path of the storm did not take it through any towns, but the strongest Iowa twister since 2008 still caused 10 injuries and devastating damage. Hail stones to 4.25 inches fell in Minnesota in Nicollet and Waseca counties. Other reports of hail greater than 2 inches came from Chippewa, Lyon, Sherburne, and Washington Counties. Severe weather struck again in Iowa and Minnesota on the 26th.

June 27th brought the tenth June tornado death in the Midwest. In St. Clair County, Michigan an EF1 tornado struck a campground killing one man and tossing RV's into a pond. Trees and power lines were damaged by thunderstorm winds from Missouri to Ohio.

Following the passage of the cold front on the 28th (Figure 6), the weather cooled down, dried out, and the region got a break a welcome break from severe weather.
 

Flooding

Flooding continued across Iowa and into neighboring states (Figure 7), though the larger urban areas avoided the worst of it. Saylorville Reservoir (Polk County), on the Des Moines River, filled to overflowing on the 29th. Water backed up to close US Hwy 30 near Boone, Iowa (Boone County).
 

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