Winnipeg isn't all that far from Chicago
Winnipeg is ±717 miles from ORD (and ±1030 miles from LEX). Do flights normally divert to an airport 2.3 times the distance as the original destination?
I would hazard a guess that similar weather could be in the vicinity of alternates to ORD
BTW, the original flight (UAL7567) scheduled for a 10:46A departure, was cancelled. After several changes of plans (including being on the runway at one point in a NWA flight to DTW), they ended up on UAL7569 back to ORD which departed at 7:03P.
Nothing like an 8+ hour delay...