On August 28, 1990 the U.S.’ only known F5 tornado to occur in August began its path of disaster in the Illinois town of Oswego, about 40 miles southwest of Chicago. The funnel, a third of a mile wide, cut its way southeastward for 16 and a half miles. The terrifying ordeal began at midafternoon around 3:15 p.m.
It wrought great destruction and human cost along its path, killing 29 and injuring 350 in the densely populated areas near Plainfield. Whole apartment complexes were no match for the extreme winds of more than 260 mph. The damage was high: nearly 500 homes destroyed as well as a church and other structures, and some 1000 buildings damaged. The estimated property loss was $160 million in 1990 dollars or about $300 million in 2015.
According to the National Weather Service, the rain-wrapped tornado was nearly impossible to see, and there are no known video or still pictures of the actual funnel in contact with the ground. A Severe Thunderstorm Watch was issued for the area an hour and 45 minutes prior to the event, but there was never a Tornado Watch in effect before the storm, nor was a Tornado Warning issued during it.
For this lack of warning to take place today with such a violent tornado would be highly improbable, but in 1990 we lacked the more rapid data updates to forecast such storms, and the U.S. Doppler network was not yet in operation to detect the intensity of the storm’s rotation. The National Weather Service Doppler units (known as NEXRAD radars) were operational nationwide by 1995. Today, it’s truly a different world of weather science than just 25 years ago.