If we get that tall coupled PNA and EPO ridge, it will build homegrown cold. It’s just physics. No WAA off the PAC coupled with low sun angle and radiating snow cover. Question is how fast and then how long to transport it south. You can probably do some sort of back of the envelope calculation on this… My intuition is something like 4-8 days to regenerate at least normal if not BN temps in central Canada, then another 3-5 days for southward transport. So if that ridge does develop with a trough in the east, maybe 6-7 days at least before you can fully flush the mild air out?