By Tom Skilling
It was an atmospheric situation destined from the start to produce the localized cloudburst-intensity rains and damaging thunderstorm wind gusts which by late Friday had hopscotched across a huge swath of northern and central Illinois--including the Rockford and Chicago areas. Machesney Park near Rockford was hit between 4:20 and 5:20 pm with 3.50" of rain while nearby Loves Park and Cherry Valley were drenched by 2" rains in just an hour.From Winnebago to Belvidere and Crystal Lake, rainfalls of 1.50 to 2.50" were reported. The same storms had raked western Ilinois' Elmwood and Knoxville with 55 to 60 mph winds, and went on to produce 63 mph gusts as they proceeded east through Lake in the Hills. Winds hit 47 and 45 mph at Geneva and South Elgin, each in the Fox Valley and whipped O'Hare with 38 mph evening gusts. At the Harrison-Dever Crib three miles offshore, 45 mph gusts swept in just hours after practice flights in preparation for the weekend's Air and Water Show had attracted flocks of mariners and shoreline observers.
The eruption of storms followed another day of scorching heat which produced Chicago's 18th and 20th days of 90-plus-degree temperatures at O'Hare and Midway Airports. Intensely hot 100-plus degree air laden with moisture--dew points exceeded 70 degrees--rode powerful southwest winds north from Texas, Oklahoma and Kansas into Nebraska and Iowa. Thunderstorms erupted as the hot, humid winds slammed into outflow boundaries left by earlier storms.
The set-up had dispatched a first line of initially impressive storms from Iowa into northern Illinois late Friday morning. That line succumbed to the storm-subduing stable air off Lake Michigan. It dissipated with stunning speed.
The same was not true of a second group of storms, which first developed in northeast Kansas and southwest Iowa. Those storms ultimately assembled into a 250-mile-long "bowed" squall line and proceeded east from the Mississippi River. Doppler radar scans revealed cloud tops of 50,000 feet. That line of storms lead to a flurry of reports of flooding, downpours and wind damage into the Quad Cities National Weather Service office Friday afternoon. It was the line which later lambasted sections of the Chicago area. At its height, it produced more the 5,300 cloud to lightning strokes per hour late Friday within a 225 mile radius of Chicago.
The heat, which carries over into Saturday and may help fuel a scattering of active slow-moving thunderstorms, comes in a month which has yet to produce a below-normal day.
Half dozen funnels reported
Spotters were out in force, watching the skies as Friday's storms marched into the area. They generated six reports of funnel clouds. There was one report that a tornado actually touched down briefly in De Kalb County.
Only one year in three has produced this many 90-degree temps by now
In the 82 years since Midway Airport's observational record began (in 1928), only 37 of them--just over a third--have managed 20 or more 90s by this date.
Deadly Russian heat wave in its 7th week but FINALLY breaking down
Rains in Russia's smoggy, drought and heat-ravaged capital of Moscow, reduced temperatures Friday. A high of 84 was reported--and Saturday temperatures appear headed for the low 80s as well. Even cooler weather is due early next week.
The hot spell has sent daytime temperatures soaring to levels never before observed in 130 years of record-keeping. Thousands may have perished in the heat, which has included 32 days of temperatures 90 or higher. By comparison, we've had only 20 such days in Chicago.
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