Central Illinois experienced its first heat wave of the season between June 15th and the June 18th where temperatures reached the mid-90s with heat index values over 100°. By midweek, the heat was gone but strong thunderstorms brought heavy rain, gusty winds and even a few tornadoes to Central Illinois.
For western parts of Central Illinois, it has been a dry start to June. Before the rain arrived, "Abnormally Dry" conditions were in place west of the Illinois River so, the rain that came was a welcomed sight. Drought-stricken parts of western Illinois received one to three inches of rain this past week, which should alleviate some of the drought conditions.
As for the rest of the region, rainfall amounts ranging from two to four inches were fairly common which is two to three times more than what is received on average during the same time period. While not depicted in the rainfall summary, some localized areas saw more than five inches of rain. The heavy rain led to localized flash flooding and road closures in the Peoria area on Wednesday and Thursday.
Here are some rainfall amounts from local area airports and here at WMBD since Tuesday...
Pontiac - 3.90"
WMBD - 2.60"
Peoria International Airport - 2.53"
Lacon - 2.49"
Galesburg - 2.38"
Bloomington - 1.09"
Additional Storm Reports
Strong to severe storms moved across Central Illinois on Wednesday producing damaging winds that took out trees and power lines across Knox, Henry, Stark, Marshall and Putnam Counties while flattening cornfields in Bureau County. A lightning strike also caused two houses to catch fire in Peoria Heights. As the slow-moving storm system swirled in to Illinois, a few strong storms produced funnel clouds and isolated landspout tornadoes across Central Illinois on Thursday and Friday.
Several funnel clouds were spotted over southern Knox and western Peoria Counties while one tornado was reported to have touched down one mile west of Yates City at 12:30 pm on Thursday. The multiple reports of funnel clouds and brief tornado touchdowns resulted in tornado warnings being issued for Knox, Peoria and northern parts of Fulton County for nearly an hour on Thursday.
Another landspout tornado touched down in SE Fulton County at 7:20 pm as another line of storms began to develop.
Landspout tornadoes are tornadoes that form in the early stages of thunderstorm development and are often impossible to spot on radar. Unlike supercells, these thunderstorms are not rotating. Instead, small circulations will occasionally develop under small thunderstorms as air moves towards the storm from all different directions. The converging air will sometimes lead to the formation of weak funnel clouds that very rarely reach the ground. If they do, they are known as landspout tornadoes which typically have a small, thin funnel extending towards the ground while the base of the tornado often has a cylindrical base of dust and debris.
The recent rain has caused the Illinois and Vermillion rivers to rise. Minor flooding is occuring along the Vermillion River in La Salle County, though it should fall below flood stage by Saturday evening. The Illinois River is projected to rise above flood stage this weekend and early next week, though only minor flooding is expected. The National Weather Service has issued Flood Warnings along the Illinois River until further notice.