Wednesday, December 14, 2016

Winter Update: Baby It's Cold Outside

Arctic sea smoke amid frigid temperatures over Lake
Superior as seen from Duluth, Minnesota at sunrise
yesterday. Photo by Matt Silverness, via Twitter.  
As expected, the worst cold wave of the young winter so far is sweeping across much of the nation, and is making a beeline for the Northeastern states.

Wind chill advisories stretch in a broad band from Montana to Ohio. Wind chill watches are up in northern New York and northern New England starting later Thursday.

There's actually two strong Arctic blasts coming through. There's the one now sweeping across the northern Tier of states. Then, after a wintry storm that is or will be causing weather hazards coast to coast, another Arctic blast will target the Plains and Midwest.

Let's take this very active weather pattern piece by piece.


In the grand scheme of things, this first cold wave isn't one for the record books, really, except for one thing: Temperatures in the mid to upper atmosphere are near record lows for this time of year. This time, it's not translating fully down to the surface where we live, but it's still plenty cold enough.

This cold wave is pretty gusty, so wind chill are the big story with this. Up here close to where I live, in Vermont and surrounding states. winds gusting to 40 mph Thursday night and early Friday combined with actual temperatures near 0 degrees will make for a most uncomfortable end of the week.

This gusty northwest flow is naturally setting up some epic lake effect snows around the Great Lakes. Winter storm warnings are up now for northern Michigan due to lake effect off Lakes Superior and Michigan.

Ohio and New York are under the gun, too, starting later today and lasting into Friday, some parts of western New York will easily get two feet of snow out of this.

Here in Vermont and the rest of northern New York and New England, the cold wave will arrive in the form of a series of cold fronts and boundaries. Each of these boundaries will pick up moisture fro the Great Lakes and those lake effect bands.

The end result is a strong risk of periodic snow showers and snow squalls, starting later today and lasting well into Thursday or Thursday evening.

It won't snow all the time, and accumulations will be light during the period - I'd say one to four inches total in the valleys. But the squalls and strong winds will cause poor visibility and icy roads. Also remember that as the cold deepens Wednesday night and Thursday, road salt will stop working, so roads will remain treacherous.


The first Arctic air mass will quickly whisk eastward away from most of the East, though it will remain cold in the Northern Plains and northern Great Lakes.

Now we're gearing up for a storm that will go coast to coast, west to east across the United States. It will be a "sandwich storm" between two blasts of Arctic air. The one coming in now, and the other over the weekend.

Already, winter storm warnings and watches extend all the way from Oregon to South Dakota. Flood watches are up in large parts of California.

The California flood watches are oddly comforting in that it means we know rain is going to fall on the still drought-plagued state.

However, some of it will come down too hard, too fast, which leads us to the risk of urban flooding, landslides and local flash flooding, especially in areas where recent wildfires stripped the landscape of trees and brush, which tends to hold the soil in place.

As the storm travel east, then northeast, expect snow to break out to the north of it in the Midwest, and snow, then mixed precipitation, then rain in the East.

Along the East Coast, the storm's path to the west through the eastern Great Lakes will mean a brief, dramatic warm up by Sunday, It'll go above freezing, probably all the way to the Canadian border for a time early Sunday. Some readings near record highs are possible south of say, Connecticut that day before the next cold blast hits.


Another really strong cold wave will follow the storm this weekend. Though the Northeast won't have it as bad as the first Arctic spell in the next couple of days. the Plains and parts of the Midwest will be brutal.

The second cold wave could hold highs down into the teens below zero in Bismarck, North Dakota for the first time since 2010. Chicago could have its first subzero high temperature in December since 1983, says the Weather Channel. 

After that, the weather pattern looks like it will shift once again, and generally milder weather will overspread much of the nation next week

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