Tuesday, November 26, 2013

Tues Morning Update: Upcoming Storm's Timing Not So Good

As I look at the forecast updates Tuesday morning, not much has changed in the thinking of how this big oncoming storm is going to behave.
Here's an early NWS/Burlington forecast of how much
snow will accumulate in northern Vermont
and New York from this storm. Click on
the image so it's bigger and easier to read.  

Some details seem to be emerging, though.

Before I go on, I have to repeat some of the caveats you probably have already seen: The forecast could still change, and we could still get some surprises.

And the weather will probably be very different over short distances in Vermont and surrounding areas. One spot might be just getting rain, while it's freezing rain just up the road, and wet snow a few miles beyond that.

Now, the particulars. A winter weather advisory is up for Vermont and a winter storm warning is in effect for northern New York away from Lake Champlain.

The scenario, as forecasters see it is this: Snow or mixed precipitation comes in early tonight. It'll be a gloppy mess of wet snow, sleet, freezing rain and rain that will continue on into the morning commute in most of the region.

Expect a thin layer of slush in the warmest spots, maybe the southern Champlain Valley, to between and inch and four inches of crud with the consistency of wet cement in much of Vermont and the northern half of New Hampshire.

In northern New York, the precipitation will stay mostly wet snow, with some mixing, through most of Wednesday. Expect 6 to 12 inches of wet snow there, which could really be a problem. Wet snow can bring down trees and power lines.

Since there will be slush and ice around in the morning, build in extra time for  your trip if you have to drive to work Wednesday morning.

As the storm moves northeastward through New Hampshire, enough warm air will probably come along to change much of the precipitation to a cold rain across Vermont for much of Wednesday. Some areas, especially across the northern mountains and perhaps the Champlain Valley way up north above St. Albans, could hang on to some mixed precipitation.

This continues to look like a very wet storm, so it could rain pretty hard at times. Wednesday by any measure will be a yucky day.

Although no watches or warnings are in effect, it might rain hard enough in parts of New Hampshire and Maine to cause some flooding. Some computer forecasting models predict more than four inches of liquid precipitation in western Maine.

Late Wednesday afternoon, we run into more problems for commuters or holiday travelers. Actually worse problems than on Wednesday morning. Cold air will quickly wrap around the back side of the storm, temperatures will crash and precipitation will change to snow.

This is bad as wet roads will freeze and snow will accumulate on top. That's the worst possible mix for scary, hazardous road conditions.

It'll snow kind of hard at times Wednesday night, especially in some parts of the Champlain Valley and definitely along the western slopes of the Green Mountains in Vermont. The Adirondacks and New Hampshire's White Mountains could also get a pretty good dump out of this.

The best guess from the National Weather Service is Wednesday night's round of snow will bring an accumulation of two to six inches. I wouldn't be at all surprised if the western slopes and the northern Vermont ski areas pick up more than six inches.  The Jay Peak cloud could dump up to a foot of powder.

If you have to travel Thursday morning, the snow will have tapered off to flurries, but the roads will still be bad. It will be another frigid day as winter has settled in for an early arrival. Many places won't make it above 20 degrees.

It'll stay cold until a slight, not dramatic warm up comes in around Sunday.

Safe travels, my friends!

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