STERLING – In addition to two Lee County tornadoes – one in Sublette, and one in Harmon – Monday’s storm also produced two separate tornadoes that touched down in Whiteside County, according to the National Weather Service.
The Whiteside County twisters – which both originated within 3.5 miles of Rock Falls – were not originally categorized as such, but were determined to be tornadoes after NWS surveyors assessed the damage. Neither resulted in injuries.
The NWS uses the Enhanced Fujita scale to indicate a tornado’s severity. Whiteside County’s twin twisters were given an EF-1 “weak” designation, second-lowest on a 6-point scale.
The first originated at 7:14 p.m. 1 mile northeast of Rock Falls. It had a 100-mph peak wind and traveled 2.19 miles southeast. It was 75 yards wide, according to the NWS, and lasted 4 minutes.
The second one started at 7:16 p.m., while the first was still raging, according to the NWS.
It was 50 yards wide, traveled 2.56 miles southeast and blew itself out 3.5 miles west of Harmon.
All four siblings were born of the same severe weather cell that stormed through the region from about 7 to 10 p.m. Although separate from the ones that touched down in Harmon and Sublette, the Whiteside tornadoes followed the same tract, said meteorologist Terry Simmons, of the Quad Cities NWS.
Chicago NWS maps show the tornado-producing storm system continued to Lee County and through Mendota, Coal City, and Kankakee.
“The surveyors looked at the [Whiteside County] damage and determined it to be tornadic,” Simmons said. “Looking at the radar and the way the damage was found, that’s how you determine some of this. You look at what pattern of damage existed.”
Surprisingly, neither tornado was related to the winds that destroyed the midsection of Sterling’s Northland Mall, Simmons said. The damage there, she said, is a testament to the destructive power even non-tornado-producing storms can bring.
In Whiteside County, the wind mostly damaged trees, power lines and house sidings, the NWS said.
The two Lee County tornadoes were less twin-like: One was a “strong” twister that blazed a path through Woodhaven Lakes in Sublette, the other a slightly weaker twisted sister that ripped the roof off a home in the village of Harmon, just over the county’s western border with Whiteside.
Harmon’s EF-1 was confirmed late Tuesday afternoon by the Lee County Emergency Management Agency and the Chicago NWS. Sublette’s EF-2 rating was confirmed earlier in the day.
One person in Harmon was taken to a local hospital with “non-life-threatening injuries,” LCEMA reported. In Woodhaven, one person suffered head injuries severe enough to require hospitalization, while several others were treated for minor injuries.
The Sublette tornado mowed a quarter-mile-wide path of damage through the south side of the private campground, taking out hundreds of trailers, while a home in Harmon, pop. 100 or so, lost its roof. A weather chaser caught that funnel cloud on video, which can be viewed on the Chicago Tribune's website.
Gov. Bruce Rauner issued a state disaster proclamation for Lee County, which will make state resources available for recovery.
Sauk Valley Media News Editor Kathleen A. Schultz contributed to this story.
The EF scale
EF-O: Weak, with winds 65 to 85 mph. EF-1: Weak, 86 to 110 mph. EF-2: Strong, 111 to 135 mph. EF-3: Strong, 136 to 165 mph. EF-4: Violent, 166 to 200 mph. EF-5: Violent, 200 mph and higher.