Total guess, but: Lake effect probably prevents huge temperature swings further east (the great lakes are GIGANTIC sinks of energy), and there are mountains to the west, I believe. The problem is the flat area pictured.
Also, the shape of the polar vortex wind mass isn’t uniform, so it likely dips further south in that region than others (in part due to the barriers described above)
Total guess, but: Lake effect probably prevents huge temperature swings further east (the great lakes are GIGANTIC sinks of energy), and there are mountains to the west, I believe. The problem is the flat area pictured.
Also, the shape of the polar vortex wind mass isn’t uniform, so it likely dips further south in that region than others (in part due to the barriers described above)