Polar vortex rules: Snowy PM drive today

Welcome to a real January in Minnesota.

A big spinning pool of frigid low pressure called the "polar vortex" is large and in charge this month Canada and the northern USA. The polar vortex roams around the far north in winter, but migrates southward at times. When it does, the slowly spinning whirl deals Minnesota and the Upper Midwest bouts of cold and (generally light) snow.

The polar vortex today is swirling over Hudson Bay and looks to be in no big hurry to move on this month.

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You can think of the polar vortex as a big bicycle wheel of low pressure. It spins slowly, and each time one of the "spokes" passes overhead, it brings a shot of light snow. These clipper like spokes generally deliver a dusting of arctic fluff.

Snowy PM Drive today:

The next spoke in the polar vortex wheel is spinning through Minnesota today. Look for a swath of snow to spread from west to east today from near Ortonville and Morris this morning eastward to the Twin Cities by mid afternoon.

Snow accumulations should generally be light, with around an inch expected for much of central and southern Minnesota. Where snow is persistent in some areas, a little more could accumulate...a little less in other areas.

With surface and pavement temps in the teens, it won't take long for roads to ice up today. Expect icy road conditions to develop today from west to east, and PM drive in the metro could produce some slick & slow travel. This will be a light snow by recent "storm" standards...but could have a higher impact due to the cold temperatures.

Long range outlook: Arctic outbreak ahead?

All atmospheric signs point to continued cold and bouts of snow for the next two weeks. As much as I'd like to see a warm up, I just don't see it in the cards though mid-month. In fact, there are signs of a significant arctic outbreak later next week, around or after January 13-15th.

If the medium range models verify, we could see sub-zero air and bitter wind chills lock in for a few days to a week over most of Minnesota and much of the eastern USA by late next week. The cold may push all the way south to Florida once again. Minnesota (including the metro) may not climb above zero for a few days if this pattern takes hold.

Stay tuned.

Slight chance of a "January Thaw" on the far horizon?

There are some (very slight) hints at a possible January thaw around or after the 20th.

As the core of the coldest arctic air drains south out of Canada in winter, it is often replaced by a much milder Pacific air mass. It's still iffy, but there are some signs that could happen around or after January 20th.

Weather fingers & toes crossed on that one. In the mean time expect a shot of snow this afternoon & evening and real January cold to dominate through mid-month.

Stay tuned, and stay warm!

PH