The tornado that killed two people and injured 125 in Washington on Nov. 17 remained on the ground for more than 46 miles and produced 190 mph winds, the National Weather Service at Lincoln reports in a review of significant regional weather events for 2013.
Ten tornadoes were tracked on Nov. 17 in an area from Peoria to Danville. Another 17 people were injured across central Illinois, including 10 in Pekin, six in Gifford and one in Westville.
The 25 tornadoes confirmed statewide was the fourth-largest outbreak in Illinois since 1950, according to the report.
"The Washington EF-4 tornado was the strongest November tornado observed since reliable records began in 1950," the weather service stated. EF-4 is the second-strongest storm on the tornado rating scale.
An unusual November mixture of warm, moist air and a powerful low-pressure system combined to produce the outbreak.
"Given temperatures of around 70 degrees, there was more than enough instability," the analysis stated. "And this instability was actually off the charts in November."
As a result of the conditions, advisories of potentially dangerous weather began going out the Thursday before the Sunday storms.
"With the parameters extremely high for anytime of year," the weather-service report stated, "long-lived significant tornadoes became likely."
The full weather-service review of 2013 can be found at http://www.crh.noaa.gov/ilx/.
Tim Landis can be reached at (217) 788-1536 or firstname.lastname@example.org. Follow him on Twitter @timlandisSJR.
An outbreak of 25 tornadoes in Illinois on Nov. 17, including 10 in central Illinois, was the worst since 1950 in the state, according to the National Weather Service at Lincoln.
Here is a summary of central Illinois storms by strength rating (EF-5 is the highest), top wind speed and miles on the ground.
Washington: EF-4, 190 mph, 46.2 miles.
Gifford: EF-3, 140 mph, 29.7 miles.
Villa Grove: EF-3, 140 mph, 18 miles.
Westville: EF-2, 130 mph, 19.7 miles.
Alamont: EF-2, 120 mph, 11.5 miles.
Pekin: EF-2, 120 mph, 2.5 miles.
Garrett: EF-1, 110 mph, 9.3 miles.
Pana: EF-1, 110 mph, 2.5 miles.
Tuscola: EF-1, 100 mph, 5.2 miles.
West Liberty: EF-1, 100 mph, 3.5 miles.