Vermont Storm Update: Still Very Windy, Wet And Wet-Snowy Thursday

National Weather Service updated snowfall prediction map issued
Wednesday afternoon. It still looks like this is going to be
an elevation snowstorm in Vermont. Click on the map
to make it bigger and easier to see. Yellow and orange
areas should expect more than six inches of snow.

Since this is going to be a pretty good storm, it's worth updating the situation, as you're going to see a lot of rain and/or snow Thursday morning. Some of us will also see a ton of wind.  You'll need to deal with it, so here you go:

THE SETUP 

This afternoon, light north winds funneled chilly air southward down the Champlain Valley, so it ended up being cooler today than expected.  (Elsewhere in Vermont, the low level cool air couldn't make it in, so today's highs ended up in the mid to upper 30s, as forecast.

This subfreezing air today, along with occasional light snow, doesn't really mean the Champlain Valley is in for a colder, snowier storm than expected tonight and tomorrow.  In fact, as of late afternoon, the snow flurries here in St. Albans had already changed to a some light sleet, mixed with a few drops of freezing rain.  That's an indication that a surge of warmer air is on its way.

For most of tonight, at least until midnight, any precipitation that does fall will be very light and spotty.  It's not until the storm pushes in from the southwest, with its strong weather front, that heavy precipitation will get going after midnight.

HEAVY RAIN/SNOW

That front will initially bring a surge of somewhat milder air, so the heavy stuff that comes down in the valleys early Thursday seems like it will be mostly rain. However, with the weather front and storm itself strengthening as it comes in, that could cool the atmosphere a bit to produce wet snow, so it's no guarantee the valleys will be mostly rain.  Let's just call that rain scenario likely, but it's possible you could be surprised.

If it is mostly rain, it come down hard for a time in the morning. There's still a fair amount of ice and snow on the ground in northern areas.  Storm drains are clogged with ice, too. Expect some urban flooding with this rain, if the forecast comes out as expected.  More than half an inch of rain in just a few hours is expected, which would be enough to cause that kind of problem on town and city streets, and maybe basements.

River and stream flooding won't be much of an issue because a large share of the precipitation that will come down in the higher elevations will be snow.

The higher in elevation you go, the more likely you are to get snow.  It still doesn't look like there will be much in mid-elevations, say around 1,000 feet. Those areas could manage a couple or thre einches. However, it's still possible we'd get a surprise with more, but so far, it's looking like a no.

If you're up above 2,000 feet in elevation in most of Vermont, you've got a great shot of getting six inches or more of snow.  Snowfall rates up there could be in the one to two inch per hour range. Especially given that it will probably be a relatively wet and heavy snow, I wouldn't drive toward the mountains Thursday morning.

HIGH WINDS

Wind gust forecast from the National Weather Service in South Burlington
That dark orange stripe along the western slopes of the Green Mountains
in eastern Rutland and Addison counties forecast gusts of at
least 60 mph early Thursday. Lighter orange shading indicates
gusts of at least 40 mph. 

Adding to this mix is the expectations that winds could get quite strong on the immediate western slopes of the Green Mountains. I mentioned this in this morning's post, and everything still seems to be aligning toward those winds.  

The strongest winds would come before or near dawn in Rutland and Addison counties, closest to those western slopes.

Winds could easily gust past 60 mph. With some snow loading on trees and power lines in higher spots, this is a recipe for power problems in and near communites like Mount Holly, Shrewsbury, Mendon, Goshen, Chittenden, Brandon and Starksboro.

Those high winds along the western slopes will spread north around or just after dawn to western slope communities like Huntington, Bolton, Jericho, Underhill, Cambridge and Bakersfield.

In those towns the wind will be a little lighter than points south along the Greens, but the gusts will be enough to risk some power line and tree issues.

The bottom line is you should prepare for a complicated Thursday morning commute, regardless of whether you get mostly rain, mostly snow, or strong winds.  You might want to charge your devices ahead of time, in case the power goes out.

THURSDAY AFTERNOON

After the front passes, heading north and east, precipitation everywhere will change to snow but become lighter. Winds will become somewhat lighter, but remain gusty. Temperatures Thursday afternoon should keep falling through the 30s and well down into the 20s.

Given that, when you're returning home from work Thursday evening, expect slick spots from continued light snow, and water from the morning freezing on roads.

INTERESTING POST-STORM ACTION

Perhaps the most interesting aspects of this storm will actually be something that will happen after the storm actually passes by.  It could have some effects here in Vermont, but first I need to set things up for you.

The storm will head north into Quebec, and there will be strong west winds behind the storm.  As I mentioned this morning, the Great Lakes aren't frozen like they usually are this time of year.  The strong winds, unstable air and the open waters of the lakes will set up some huge lake effect storms downwind from the lakes.

There's strong indications that an epic lake effect snow band will generate itself on Lake Superior, get more energy as it moves east-southeast across Lake Huron, then heads due east across Lake Ontario into the areas near and south of Watertown, New York.

This is especially true south of Watertown in the infamous snow belt area called the Tug Hill Plateau. They are so going to get slammed.

There's a blizzard warning for this area near and south of Watertown for an expected three to four feet of snow on the Tug Hill Plateau and one to two feet in surrounding areas.  This will be propelled by winds gusting to 50 to 60 mph.  You can imagine the huge drifts, zero visibility and difficulties with this situation.

Vermont won't get anything like that. But I've seen that in cases where there's such a powerful lake effect band with such strong winds, some Vermont higher elevations can get quite a bit of snow.

The lake effect snow band, while slightly weakened will extend across the Adirondacks. Generally, the remains of these snow bands skip the Champlain Valley as the Adirondacks block the moisture associated with these snow squalls.  Still, little upper level disturbances in this fast west to east flow behind the storm can help bring some snow from this lake effect into the Champlain Valley.

People in the Champlain Valley won't get much snow out of this, but an inch or two of accumulation could slicken up the roads Thursday night and Friday.  Just sayin'.

The real point of this little story is what happens when the remains of this snow band hit the central and northern Green Mountains. Since this thing is pretty narrow, not everybody in the mountains will get a lot of snow. But in my opinion there's the potential for six or more inches of snow somewhere in the mountains of northern Vermont after the main storm.

All because of this lake effect snow band.  The snow band could move back and forth for a time spreading some snow through the entire Green Mountain chain north of Killington. Or it could focus on a specific area and really come down.  Parts of the Northeast Kingdom could also get in on this action, especially since weather patterns suggest the atmospher might interact with parts of the lake effect stuff up there.

It's not certain all this will happen. But I think it might. The National Weather Service in South Burlington isn't focusing on this right now, because they have their hands full with the immediate storm.  This post-storm snow thingy is just something to watch.

Mostly because it could help make for another great weekend of  skiing and riding, between Thursday's high elevation snow and the post-storm snow showers.

AFTER THAT

It'll be a pretty chilly, wintry weekend across Vermont, which is to be expected as the calendar just turns from February to March. But another period of warm-ish weather seems likely for the first half of next week.  Again, that's something you have to expect now that we're getting into March.