Surprise Vermont Snow Had Source In Warm Great Lakes

A car slid off the road in yesterday's surprise snow in Williston,
Vermont. Image from WCAX-TV

Surprise!

I didn't tell you it was going to snow yesterday in Vermont, beyond flurries. Neither did the National Weather Service or all the other good meteorologists in the Vermont media.

Yet, Burlington got its first measurable snowfall of the season, with 1.3 inches.

The western slopes of the Green Mountains got clobbered, with 6 inches of new snow reported in Jericho Center and 5 inches in Jonesville, which is sandwiched between Richmond and Bolton, Vermont.

I'm sure the surprise snow cheered Thanksgiving week skiers, but motorists grumbled over the unexpectedly slick roads. There were a number of accidents and slide-offs.

So what  happened?

Forecasters knew there was enough moisture coming off the Great Lakes to pose the risk of snow flurries on Monday, especially along the western slopes of the Green Mountains.

However, when subtle weather disturbances get involved with lake effect snows from the Great Lakes this time of year, surprising things can happen.

This is prime lake effect snow season for the Great Lakes. There's virtually no ice on the any of the lakes yet, so they're wide open. Cold northwest winds can pick up moisture from anywhere on those lakes and deposit snow on downwind shores.

The lakes are also relatively warm. In fact, warmer than normal for this time of year. If the contrast between cold air and the lakes increases because the water is toastier than usual, you can get more widespread lake effect snows.

As of yesterday morning, lake effect snow was coming off all the Great Lakes.  The snows from the Great Lakes sometimes make it all the way to Vermont's Green Mountains, but usually it's only a limited amount of snow, confined to the upper elevations in a narrow area of the state's mountains.

But a very subtle weather disturbance - almost too small to be detected by meteorologists - moved over the Great Lakes and made it into northwestern New England yesterday. This disturbance was able to pick up lake effect snows from Lakes Superior, Huron, Ontario and Erie and bring it all the way over to us.

Hence the surprise snow. It is kind of cool in a weather geeky way that we managed to get lake effect snow in Vermont from four of the five Great Lakes.

It's warmer today and tonight ahead of a cold front, so some of the snow will melt. But don't worry, skiers and riders! The general trend through early next week is for chilly weather. Cold fronts tomorrow and Sunday will bring more mountain snow showers, ,and possible a little more lake effect snows courtesy of the Great Lakes.