National Weather Service United States Department of Commerce

Dangerous Heat Continues; Monitoring Excessive Rainfall and Flash Flooding

The heat continues along and east of the Mississippi River. The most significant cumulative heat impacts are expected across the Mid-Atlantic through today and eastern Ohio Valley through Friday. Severe weather and heavy rainfall potential from the Southwest, Plains, upper Midwest, Great Lakes, mid-Atlantic and Northeast the next couple of days. A disturbance near the Marianas may bring flooding. Read More >

Overview

 

Severe thunderstorms developed across eastern Iowa and northwest Illinois Saturday, July 11, 2020, producing widespread wind damage and very large hail.

The first line of storms came through during the morning, producing damaging wind gusts and reports of quarter to ping pong ball size hail from Independence IA to Tipton IA. A wind gusts of 65 MPH was measured just west of Independence IA.

The second round of thunderstorms developed as a result of an upper level disturbance interacting with an atmosphere characterized by extremely high instability with modest vertical wind shear. Activity initially formed in north central Iowa, producing golf ball to two inch hail from Fort Dodge IA to Waterloo IA. Eventually, storms made their way towards the Cedar Rapids/Iowa City metros, producing widespread wind damage and hail up to baseball size. These storms continued through the Quad Cities metro east towards Princeton IL, Sterling IL and Hennepin IL, producing additional reports of wind damage and winds of 70-90 MPH. Numerous power outages were also reported.

 

Surrounding Office Event Summaries

NWS Chicago

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Sun Illuminating Striations and Mammatus Clouds After Squall Line Exited the Quad Cites Metro (Photo by David Cousins)