Thursday, January 5, 2017

Three Big Winter Storm Trouble Spots This Week

An intense lake effect snow band on radar this morning
south of Buffalo, New Hork. The band was expected
to move north into Buffalo this afternoon in
time for the evening commute. 
As I write this, three areas of the country are definitely screwed in terms of winter weather: Western New York and other areas near the Great Lakes, parts of the southeastern United States, and definitely California.

I'll take these in chronological order.

WESTERN NEW YORK:

Big lake effect snows were going on as I wrote this at mid-morning. Some of the more favored areas for lake effect, like the Tug Hill Plateau not far from Watertown, New York, could get three or more feet of snow out of this by Friday afternoon.

Already, up to two feet of snow has fallen in some spots since yesterday, like in the town of Copenhagen, New York.  

Snow in the intense lake effect bands were coming down at a rate of two to three inches per hour around Watertown, New York, near Lake Ontario, and south of Buffalo, near Lake Erie.

These intense snow bands will drift northward today amid shifting winds, so very heavy snow will likely be coming down right in the middle of the Buffalo metro area during today's afternoon commute.

The bands will slowly sink southward tonight, so big areas of western New York are in for some good snows. Other nasty lake effect snows are occuring in Ohio and Michigan

Vermont effects: For my Vermont readers, weak disturbances in the upper air flow will help pick up some moisture from the lake effect. That could translate to a dustings of snow in the valleys and maybe a few inches of fluff in the mountains.

THE SOUTHEASTc

Winter storm watches are up for Friday and Saturday from central Alabama, through northern Georgia and parts of South and North Carolina.

A cold airmass has settled south into the region, and a storm will zip through just south of the winter storm watch area.

That means an outbreak of snow and ice is a very good bet in this region.

By northern standards, this isn't that big a deal. For instance, Atlanta is expecting one to three inches of snow out of this thing. Up toward Raleigh, North Carolina, the thinking is they'll get two to five inches of snow and sleet. 

A fair amount of sleet and freezing rain is possible closer to the coasts of North and South Carolina, so that's definitely a threat.

Also, there's a chance this storm could be quite a bit worse up in the Carolinas. More than six inches could come down in some places within shouting distance of Raleigh. A few computer models drop a foot of snow. Kinda doubt it, but could happen.

The South is much less accustomed to wintry weather than those of us up here in the North, so that amount of snow will definitely cause some problems in the big metro areas in the Southeast.

This storm should leave the Southeast by Saturday afternoon.

Vermont effects: None. The storm will go out to sea, then pass well southeast of Cape Cod over the weekend.

CALIFORNIA:

As I noted yesterday, an "atmopheric river" of intense moisture is expected to hit the state over the weekend.

Widespread flood watches are already up for the state for five to 15 inches of rain in many areas.

What makes this even more concerning is it's going to get warm in the high elevations of the Sierra Nevada. Heavy rain could fall at elevations of 9,000 feet or more, a zone that usually gets snow during winter storms this time of year.

The heavy rain, combined with melting from existing snow cover could easily make the expected floods worse.

Also, this has implications for the upcoming summer. You want snow to accumulate in the Sierra now, then melt in the summer for water supplies. If too much melts now, there won't be much left in the spring. We could end up with the odd scenario of above normal winter precipitation in the Sierra but with a weaker than normal snowpack.

Already Yosemite National Park is considering closing this weekend because of the flood threat, and state officials are warning of widespread road closures and flooding through much of central and northern California.

Of the three winter storms I highlighted, the California storm is likely to be by far the most damaging and the most life threatening. People in California ought to be preparing now, and be ready to act during flood emergencies on a moment's notice.

Vermont effects: Uncertain. The California atmospheric river will help generate storm systems that will cross the country next week and possibly the week after, but it's too soon to say precisely what effect, if any, these storms will have on the Green Mountain State.

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