Although August has been relatively quiet, cool, and dry, the summer of 2015 will be remembered as a wet and active season across the Midwest and Ohio Valley. Unlike last year, this summer featured close to average temperatures, only at max one degree below normal. June and July were the main contributors of both severe weather and rainfall across Illinois, Indiana, and Ohio as the result of Mesoscale Convective Systems (MCS) and the remnants of Tropical Storm Bill. These average temperatures and above average rainfall amounts have provided a bit of jealousy with their hot and dry Northeast neighbors.
Accumulated Precipitation and Average Temperatures from June 1st to August 31st for the Midwest, courtesy of the Midwestern Regional Cimate Center.
The most impressive stats from the summer of 2015 were in the precipitation department, where Indianapolis saw its wettest summer on record with a whopping 23.05" of rain. More than half of this rainfall was seen in July, with 13.14"observed. This ranked July 2015 the wettest July on record. In fact, the summer as a whole only experiences 11.59" of rainfall at Indianapolis International, making the July total even more remarkable! In addition, the Midwest saw some of their top ten wettest Junes on record, with Dayton taking the lead with their 3rd wettest June at 7.88", Indianapolis coming in 4th at 7.12", and Cincinnati in 5th at 7.33". Chicago and Columbus ended up in 7th place with 7.12" and 6.72", respectively. While the beginning of the summer was abnormally wet, August finally settled down with drier conditions dominating as high pressure anchored over the region. Parts of Ohio even saw their 3rd driest August on record, with rainfall deficits of 2 - 3 inches.
Switching gears to temperatures, June started off relatively cool, then readings peaked toward the end of July with a subborn ridge of high pressure. Into August, temperatures began to gradually trend cooler, despite warmer fluctuations from time to time. Even with a taste of fall during the 3rd week of August, in general, no abnormal monthly average temperatures stand out for this season.
Though temperature trends were relatively unimpressive, an active severe season plagued the Midwest. Southwest of the Chicago metro area, 10 tornadoes were witnessed from a persistent supercell that travelled from Whiteside to Kankakee county on June 22nd, the strongest of which produced an EF-3 tornado in Coal City, Illinois. Another notable event includes a long-lived squall line that spanned from Wisconsin to South Carolina, leaving significant wind damage in its wake. Though August was relatively quiet severe weather wise, the 18th of the month saw isolated supercells that produced EF-0 tornadoes, one of which passed eerily close to Cook County as winds of 50 - 75 mph ripped through Bolingbrook and Downers Grove. This same storm passed over the Chicago National Weather Service office, resulting in a nearby office in Lincoln, IL to take the reigns as the Chicago staff took shelter.
Graphic courtesy of the Chicago National Weather Service for the August 18th, 2015 storms, in which the circulation passed right over their office, forcing them to take shelter.
With the summer winding down, it's only a matter of time before the leaves begin changing and crisp air starts funneling down from Canada. Enjoy the warmth while it lasts!
