Top Weather Events of 2010
North Central and Northeast Illinois, and Northwest Indiana
Jim Allsopp, Warning Coordination Meteorologist
National Weather Service, Chicago
Long Relentless Winter – The winter of 2009-2010 brought above normal snowfall and slightly below normal temperatures. Chicago had 54.2 inches of snow for the season, 16.2 above normal. Rockford had 50.7 inches, 12 inches above normal. It was the third straight season with more than 50 inches of snow for both cities. That had never occurred before in Rockford, only occurred once before in Chicago, 1976-77, 1977-78, and 1978-79. The snow was very persistent. Rockford had at least an inch of snow covering the ground continuously for 47 days from December 8 through January 23. In Chicago, snow covered the ground nearly continuously from December 19 through March 5, except for 3 days in January and 4 days in February. It was not extremely cold, but persistently cold. Chicago only recorded one sub zero temperature the entire winter. But the temperature reached 40 degrees only four times between December 3 and March 3 at both Rockford and Chicago. There were 14 deaths due to exposure to cold during the winter, all but one occurring in Cook County.
Early January Cold – Early January brought the coldest weather of 2010. In Chicago, the high was 11 on January 2 and the low was -1 on January 3. It was the only sub-zero temperature recorded in Chicago last winter. Rockford was below zero seven of the first ten days of January (total of ten days for the season) with a high of 7 on January 2 and a low of -8 on January 3. Rockford’s coldest temperature was -10 on the 10th.
January 6-8 Heavy Snow - A winter storm brought 6 to 8 inches of snow over north central and northeast Illinois, especially near Lake Michigan, including 7.5 inches at O’Hare, and 6.2 inches at Rockford, while 6 to 12 inches fell over northwest Indiana.
Map of snowfall January 6-8, 2010
February 8-10 Heavy Snow - A winter storm brought 7 to 14 inches of snow to north central and northeast Illinois as well as northwest Indiana, including 12.9 inches at O’Hare and 7.4 inches at Rockford. Again, the heaviest snowfall was near Lake Michigan.
Map of snowfall February 8-10, 2010
April 5-6 Supercells – A large, elevated supercell moved from Ogle County east to the north side of Chicago during the evening of April 5th. Although the storm was a classic supercell with strong rotation and a hook echo, cool stable air in the lowest 5000 feet of the atmosphere prevented this storm from producing a tornado and far greater damage. However, the storm did produce a swath of hail and wind damage. A corn crib and machine shed were destroyed, and other outbuildings damaged west of Polo. Trees were blown down and more outbuildings were damaged across Ogle, Lee, DeKalb, and Kane Counties. In Bensenville, the roof of an auto shop was damaged by 60 to 70 mph winds. The storm produced hailstones from penny to golf ball size along much of its path. The largest hail, some the size of baseballs, fell near Des Plaines. Additional storms produced hail to the size of golf balls and wind damage into the early morning hours of April 6.
Doppler radar image of supercell storm near O’Hare Airport April 5, 2010
June 5 Tornado Outbreak – A dozen tornadoes struck the NWS Chicago forecast and warning area. One supercell produced ten of the tornadoes along a path from Streator to Dwight to just south of Kankakee. One person was killed and 32 were injured. The strongest tornadoes were rated EF3, one over rural northern Livingston County and the other near St. Anne in Kankakee County. EF2 tornadoes struck Streator and Dwight.
Two tornadoes near St. Anne, Kankakee County, June 5, 2010 – photo by Brandon Redmond
June 18 Bow Echo – A fast moving, arc shaped line of thunderstorms, known as a bow echo, swept across northern Illinois and northwest Indiana producing damaging winds gusts in excess of 60 mph. The storms caused damage to trees and power lines. The roof of a house was damaged in Winnebago County. Roofs were ripped off buildings in Rochelle. A bowling alley sustained roof damage in Antioch. The Allstate Arena roof was damaged in Rosemont, and a nearby garage was damaged. Windows were blown out of the Willis Tower and buildings were also damaged at State and Randolph. Thousands of trees and poles were damaged in Chicago.
Radar image of bow echo over northern Illinois June 18, 2010
Roof damage at a car dealership in Rochelle, June 18, 2010 – photo by Mike Katz
June 23 Severe Storms and Tornadoes – A line of severe thunderstorms moved southeast across northern Illinois and northwest Indiana, some producing winds in excess of 60 mph. One of the strongest storms struck Elmhurst and Oak Brook, producing winds in excess of 90 mph, which blew down large trees and light poles, and caused damage to roofs. Another storm produced a brief EF1 tornado at Matteson.
Roof damage to an office building and trees blown down in Oak Brook, June 23, 2010
July 23 Flooding – Very heavy rain fell across northern Illinois from Ogle County to Cook County. Rainfall totals from July 21 to 23 were 6 to 12 inches. Hard hit areas included north central DuPage and Cook Counties, where many roads and basements were flooded. The flooding caused an estimated $250 million in damages.
Rainfall totals from July 23 through 25 2010
Warm Summer – Just as winter was persistently cold but not extremely cold, summer was persistently warm, but not extremely hot. During the summer of 2010 the average temperature in Chicago was 75.2 degrees, which was 4.1 degrees above normal. It was the eight warmest summer of all time. In Rockford the average temperature was 73.5, which was 2.6 degrees above normal, 15th warmest on record. Chicago had 21 days with a temperature of 90 or greater, which is close to the normal of 19. The hottest day was 94 on July 23. Rockford only had 13 days in the 90s, which is near the normal of 14, and the warmest day was only 92, which occurred July 14 and again August 29. However, from April through October, the temperature reached at least 80 degrees ninety eight times in Chicago, the seventh greatest number of 80 degree days in a year. Rockford reached 80 degrees one hundred times. It was the twentieth time Rockford recorded at least 100 days of 80 degrees in a year. The temperature reached at least 80 degrees on 46 consecutive days in Chicago, from July 2 to August 16. That was a record.
Late October Record Setting Low Pressure – Driven by a 150 mph jet stream, a very intense storm deepened to 28.21 inches of mercury over northern Minnesota on October 26. This was one of the deepest low pressure systems to ever occur over the continental U.S. As the storm moved through the Midwest, severe thunderstorms developed ahead of a trailing cold front. Despite the fact that it was before sunrise in late October, the storms produced four tornadoes over northern Illinois and northwest Indiana; an EF2 near Peotone in Will County, an EF1 near Elburn in Kane County, an EF1 near Ashton in Lee County, and an EF0 near Kouts in Porter County. After the cold front passed, and as the storm deepened, winds blew at 20 to 35 mph with a few gusts in excess of 50 mph for two days, downing tree limbs and power lines. The circulation of the massive storm covered half of North America.
Low pressure recorded over Minnesota on October 26, 2010
Photo of funnel near Peotone October 26, 2010. Photo courtesy of Carol Cantone
November 22 Tornado – A strong late fall Midwest storm, fueled by a powerful jet stream, brought a surge of unseasonably mild and humid air to northern Illinois. Strong thunderstorms developed in the afternoon, producing hail and gusty winds. An EF2 tornado formed just northeast of Rockford, near Loves Park and continued northeast through Caledonia in Boone County to just north of Harvard in McHenry County, closely paralleling the path of the January 7, 2008 tornado. In the past 130 years, only 9 EF2 or F2 tornadoes have been documented over north central or northeast Illinois. Only two other tornadoes of this strength have ever been documented later in the year, December 4, 1955 and December 7, 1951.
Tornado near Caledonia, November 22, 2010. Photo courtesy of Sean Lyon
December 12-14 Winter Storm – Rain changed to snow on the night of December 12 as a low pressure system tracked across the region. On Sunday morning December 13 the strong winter storm brought powerful north winds, wind driven snow, and sub zero wind chills to northern Illinois, heavy lake effect snow to northwest Indiana, and large waves to Lake Michigan. Most of the area only received 1 to 4 inches of snow, but north winds gusting to 45 to 55 mph caused near blizzard conditions, especially in open rural areas. This led to numerous accidents, stranded motorists, downed tree limbs and power lines, and many flight delays and cancelations at O’Hare. The strong winds generated 15 to 20 foot waves which flooded roads and eroded beaches from the Chicago lakefront into northern Indiana. As the cold air plunged south behind the storm, lake effect snow impacted mainly Porter County in northwest Indiana, where 6 to 14 inches of snow fell.
Beach erosion, Indiana Dunes, December 13, 2010. Photo by Doug Stukey
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