yeah it gets cold because of a trough. the polar vortex is not really a ground level phenomenon. saying the polar vortex is centered over hudson bay is just wrong. that's a trough.
after the (perhaps I should specify) stratospheric polar vortex settles down, as forecast, it would tend to indicate milder conditions. granted, somewhat after mid-month.
not all cold is "polar vortex" although that's how it gets used in the popular vernacular ever since that one PV split in like Nov 2014
Is it just a trough though? Modeling has it cut off completely as riding builds overhead. I think it is a secondary PV. But again, I am possibly wrong. I just know modeling shows it getting frigid.
One additional note: the Great Lakes are frigid compared to normal, and the last two years. I think they will freeze completely and thoroughly this year with melt-out delayed til May and June in Superior and Huron.
https://www.glerl.noaa.gov/res/glcfs/compare_years/11/3/2018 vs. 11/3/2016:
Superior: whole volume, -1.8F, surface, -3.8F
Michigan: whole volume, -3.1F, surface, -4.2F
Huron: whole volume, -2.6F, surface, -3.8F
Erie: whole volume, -4.6F, surface, -5.1F
Ontario: whole volume, -2.6F, surface, -3.4F
I would think that the combination of the cold in HB / GL (both residuals of this frigid spring and late melt), are additional indicators for a very severe winter in the US & Canadian East. Superior is probably going to freeze VERY solidly.