A representative from Southwest said in an online statement that the company "proactively" canceled 220 flights as of midday, and suspended service for the rest of Sunday "for the safety of our customers and crews".
Alyssa Eliasen, a spokesperson for the airline, said Southwest had 'actively worked to manage our glycol levels (used to deice aircraft),' but that due to the severity of the winter weather it was forced to cancel the flights.
The severe weather front that has hit Chicago grounded over 250 flights that were scheduled to leave Midway on Sunday. By late Sunday, a total of 235 flights on all airlines were canceled and the average delay on departing flights was around 22 minutes as of 4pm on Sunday. The airline blamed freezing conditions at Midway Airport for slowing down deice crews around the holidays. Southwest said it was hard to anticipate the snowy conditions in Chicago, which is understandable if you live in the dark ages and don't look at any weather websites or their tv channels, but Sunday wasn't the first time that this had happened to Southwest at Midway.
When smoke appeared in the cabin, the crew chose to evacuate the plane. The Southwest 737 was bound for San Jose but had to turn around and evacuate passengers using a slide before it was able to fully return to the gate.
Chicago has seen nine consecutive days of snowfall, according to the Tribune, which matches a record for the city since the National Weather Service began keeping records in 1885.