A busy Wednesday afternoon for weather buffs
All the ingredients were in place – a moist unstable air mass overhead, temperatures warming into the upper 80s and lower 90s, and an upper-air disturbance accompanied by cool air aloft – and the Slight Risk of Severe storms that had been issued early by the National Storm Prediction Center verified across the entire Chicago area Wednesday afternoon.
Once the cumulus clouds formed midday, they became towering thunderheads in a matter of minutes and continued to pulse up and die down quickly the remainder of the afternoon.
Hail the size of quarters and half-dollars were first reported in the Belvidere area, and soon after damaging winds downed trees and power lines across McHenry and Lake Counties.
Heavy downpours led to flash flooding in many areas with over an inch accumulating in a half-hour at many locations.
By the end of the day, every county in northeast Illinois and northwest Indiana had been hit by either large hail, strong winds or flooding downpours.