) A moist and unstable environment produced conditions ripe for severe weather, as clusters of intense thunderstorms moved over western Illinois during the late afternoon and evening hours. One storm produced a 70 mph wind gust at the Quad City Airport in Moline.
Every event with a place to put it; 5 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS DVN wrote it up.
Summary for 7/23/99: (For additional details, see individual reports for the date.) A moist and unstable environment produced conditions ripe for severe weather, as clusters of intense thunderstorms moved over western Illinois during the late afternoon and evening hours. One storm produced a 70 mph wind gust at the Quad City Airport in Moline. Hail to 3/4 inch and damaging lightning were reported in Stephenson County. Urban and small stream flooding occurred over four counties in northwest Illinois. Torrential rain produced six inches of standing water on Interstate 80 east of Annawan.
The Quad Cities radar (KDVN), 112 km away, was scanning. The volume nearest the first event began at 00:04 UTC.
4 flood, 1 hail, 1 lightning. Local standard time, as filed.
Thunderstorms produced rainfall amounts of 3 to 4 inches, which caused urban and small stream flooding.
Thunderstorms produced rainfall amounts of 3 to 4 inches, which produced urban and small stream flooding.
Law enforcement reported 3/4 inch hail in Freeport.
Heavy rains caused urban and small stream flooding in Rock Island County.
A NWS spotter reported trees downed by lightning in Orangeville.
A NWS spotter reported six inches of standing water on Interstate 80 just east of Annawan.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 1999Every state in 1999This day in weather historyWarnings in Illinois, July 1999
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 5718357, 5718358, 5718354, 5718359, 5718356, 5718355.