A powerful squall line -- at one point racing southeast at 60 m.p.h. and generating 700
cloud to ground lightning strikes every 10 minutes -- arrived with eye-catching fury
late Thursday. Downpours accompanied by wind gusts as high as 75 m.p.h. swept
Janesville, Wis., then moved on to north suburban Wheeling (63 m.p.h.) and McHenry
County's Lake in the Hills (60 m.p.h.). Some trees were downed primarily across the
northwest suburbs. The evening squalls began 600 miles to the northwest at around 6
a.m. Thursday in North Dakota. The southeastbound and persistent line of storms,
referred to by meteorologists as a derecho, produced damage over four states --
lambasting the Twin Cities around lunchtime and downing trees in the Madison, Wis.,
area mid-afternoon. Hail up to 3 inches in diameter bombarded Winsted, Minn. The
storms came on the heels of a nearly stationary cluster of storms responsible for hours
of lightning and rain centered on Lee County west of Chicago, where as much as 4.75
inches of rain fell at Sublette and 3.50 inches at Amboy.
MERCURY HEADED FOR 93 DEGREES THEN NEW STORMS TO HIT
New, potentially powerful storms develop in the wake of Friday's 93-degree heat late
Friday night.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune
