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Severe Thunderstorms and Excessive Rainfall in the Mid-Atlantic; Heat and Fire Weather Concerns in the West

Scattered strong to severe storms, excessive rainfall, and flooding are expected across parts of the Mid-Atlantic into the Northeast today. Flood Watches are in effect. Heat will continue to impact the West today. Heat advisories are in effect for portions of the Intermountain West; and Extreme Heat Warnings are in effect for portions of Arizona and southeast California. Read More >

Overview

  • Wind gusts of 45 to 65 mph were observed across northern Illinois and northwest Indiana. The strongest winds were associated with fast moving snow squalls. Multiple instances of wind damage occurred, including large trees and tree limbs and power lines downed, with isolated minor structural damage also reported. The high winds caused fairly widespread power outages, with about 80,000 customers without power in northern Illinois at its peak according to ComEd. 
  • The peak wind gusts at both Chicago O'Hare and Rockford were 61 mph, which were the strongest wind gusts observed at automated observation sites. At coastal platforms, the strongest observed wind gust was 65 mph at the Michigan City C-Man Station.
    • ​The 61 mph wind gust observed at Chicago O'Hare was the highest wind gust there since 62 mph on February 19, 2016. 
    • The 61 mph wind gust observed at Rockford was the highest wind gust there since 65 mph on July 13, 2015.
  • Numerous snow showers, at times mixed with graupel and rain, moved over northern Illinois and northwest Indiana during the early to mid afternoon hours. These were what we call convective showers, in that they were formed by simliar processes to convection...or thunderstorms. Thus they produced brief but heavy snowfall rates.  Combined with the winds this brought brief near white-out conditions, including here outside NWS Chicago in Romeoville just prior to 2pm CDT. 1/4 mile visibility was officially observed at the Lewis University Airport (KLOT) AWOS (Automated Weather Observation System) at 1:55 pm CDT before power was knocked out by the strong winds gusting up to 60 mph.
  • A long duration of northwest winds of about 50-60 mph (65 mph peak at Michigan City C-Man Station) over southern Lake Michigan drove very large waves. The highest observed wave heights at the buoy 6 miles north of Michigan City were 15 feet. 
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Additional recaps can be found on the NWS Chicago Past Events Page

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