Will We Have to Pay For This? - Update

 Four days ago I mentioned that the computer forecasts were “hinting” at some colder weather starting around the 23rd. Four days later, they’re still hinting at it, albeit a stronger hint. But we’re starting to see some potential details. 

First, the odds of colder temperatures next weekend are probably about 60% now. Not a done deal, but likely. There’s still a lot of uncertainty. Some computers give us sub-zero low temperatures while others say we won’t go below freezing. Your app is probably saying teens for a low, and that’s the best guess right now. But it could be colder.

There are three sources of uncertainty:

  1. Will the cold Canadian air push in from the northeast?
  2. Will this bring us snow?
  3. Will the skies clear with calm winds after the snow stops?
Canadian Air

The models have been showing this potential consistently and the trend has been to push the Canadian air in here a little stronger. So for question #1 I’d answer: Yes.

Snow Potential

If the Canadian air comes blasting in from the northeast, we usually get a frigid wind but only a dusting of snow.  At this point I’d say there’s a chance this could happen. Here’s the latest GFS wind forecast. Strong cold northeast winds.




The result of this would be more snow to our south, like the latest GFS predicts. 




But there’s an equal chance that the cold air just “seeps” in.  The reason is that a rather strong low pressure system could develop somewhere in the Northwest. This could lead to a decent snowfall event.  Here’s the European snowfall forecast. You might notice that the Canadian air will be cold enough to possibly bring snow to Seattle and Portland. 




Clear Skies and Light Winds

So if we get the Canadian air and if we get a fresh snow cover, then sub-zero nights would be possible if the skies were clear. This far out that’s impossible to predict. But based on past experience, after the snow stops in these kinds of patterns, the skies often clear up at least a bit.  If all of these factors come together, we could see sub-zero temperatures on Sunday and/or Monday morning.  But the odds of this are low. We could get the Canadian air and snowfall, but stay cloudy with a low in the teens. 

So how long would we be in this cold pattern?  Surprisingly not very long. Our flow pattern quickly does a 180 reversal and we could be back into the 40s by Tuesday the 27th. 

As I said, the odds of this scenario are low, especially given this winter pattern so far. So stay tuned to updates as we get closer. 


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