Downburst Crosses KLOT Doppler Radar on June 29, 2012

Downburst Crosses KLOT Doppler Radar 6/29/2012

On the evening of June 29, 2012, a severe thunderstorm spawned a downburst which resulted in a swath of 75 to 95 mph winds across portions of central and eastern Kendall and northern Will Counties. Numerous damage reports were received which included downed power lines, uprooted trees, broken tree limbs, as well as some structural damage. The storm passed right over the KLOT Doppler Radar which resulted in an optimal Doppler Radar measurement of the wind speeds. The images below show the progression of the storm as it approached and crossed over the radar. The green and blue colors on the velocity images show wind blowing toward the radar, while the red and orange colors show winds blowing away from the radar. As the storm approaches the radar, the radar beam samples winds closer to the ground. Click on the images to see a larger version.

925 PM: Reflectivity (left) and Velocity (right) - approximate wind speeds ~ 1170 ft AGL

939 PM: Reflectivity (left) and Velocity (right) - approximate wind speeds ~ 440 ft AGL

949 PM: Reflectivity (left) and Velocity (right) - approximate wind speeds ~ 110 ft AGL

951 PM: Reflectivity (left) and Velocity (right) - approximate wind speeds ~ 150 ft AGL

A sample of the highest reported wind speeds.

Location	Wind Speed (mph)
5 miles south of Oswego	92
NWS office in Romeoville	87
Plainfield	70
2 miles NW of Lockport	80-90

MDB/KJB 6/30/2012