While the Lower 48 basks in warmth, those days are numbered for the East and have ended further west. Many are doubting this winter, asking whether it will ever truely get here given that we’re now into December and we’ve seen the warmest opening three days on record.

I urge you to look at the big picture and compare to last year. This year won’t be anything like last year across the US and yes, there will be plenty of snow and cold to come and not too far down the road either.

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The NAO/AO is behaving very differently to last year and as for the all important PNA which is the ridge which builds up the West Coast, punches into the cold up in Alaska and sends the severe cold, arctic air south, well that will flip to positive soon enough and when it does, be sure to have your warm gear at hand.

Another key difference to this time last year is the amount of snow covering Canada. During November, there was record snows in parts of the West and Prairies and the nationwide expanse was much more suited to deep in winter, not November, this is helping keep some unusually cold air across most of Canada and despite the warming in recent days across southern Ontario and Quebec, the cold pool throughout Canada is much stronger than normal and not just confined to the north. Check out this snow cover/depth chart and you can see what I mean. Only areas that are bare are southern Ontario, southern Quebec and parts of the Maritimes.

The stage is being set, the low this morning dipped to a bone-numbing -58 degrees at Tok, Alaska. This marks the lowest reading so far and it’s the bottom of a downward temperature spiral that’s been going on for weeks.

The trouble is, like when there was a positive AO, the cold air is bundled and when you have snow on the ground, little sun and arctic high pressure in place, that cold only builds in place and when it breaks loose, it comes down with much greater ferocity.

While it won’t come down as a oner, it is likely to come down in stages and that process kicks in by this weekend and especially next week. Modelling indicates that by mid-December the snow will expand significantly across the Northern Tier and once that carpet is laid, so the arctic air will begin to bleed further and further south.

Firstly, take a long at the lack of snow covering the Lower 48 and then check out the snow projections for next week off the NCEP GFS model.

Next Thursday

Below is for 312 hours, Dec 18 and notice the model has snow down to North Texas extending northeast with a brighter strip up towards Chicago indicating a snowstorm. Also notice the snow over the Interior Northeast.

Below is temperature projections. Like I say, the arctic air comes down in stages and with each poush will come more snow.

Check this out by 114 hours

By 186… ouch!!

Finally, looking way out at 324 hours, Dec 19…. Just look at how cold that air is dropping into the Dakotas and Minnesota. Mighty impressive. There is NO SHORTAGE of VERY COLD ARCTIC AIR and all it takes is time and the buildup of cold will break loose. The thing with this type of setup is, that once it starts coming down, will it give up much over the coming 2-3 months?

A tough Pre-Christmas period to come that’s for sure.

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