Saturday Evening Vermont Storm Update: On The Cusp Of A Doozie

Expected snow amounts continue to tick upward, as
this afternoon's forecast map from the National Weather
Service shows. Some mountains could see two
feet of snow by Monday night. There's a high
bust potential with the forecast, though. 

 We're now on the cusp of our big storm, with rain and mountain snow beginning to overspread Vermont and surrounding areas.

The overall picture still has us in a two-part storm with the first big blast of precipitation tonight and early Sunday, followed by a lull during the day. Later Sunday through Monday, the snow will pick up again in at least parts of Vermont. 

Here are the main headlines, then the details:

-- Expect difficult travel overnight and early Sunday, mostly in mid and high elevations. Gusty winds combined with the heavy wet snow could lead to a lot of power outages

--- Expect the unexpected. Some areas could see much more rain, or much more snow that forecast. It's a tossup kinda storm.

--- If more rain falls than expected, there could be some minor lowland flooding again.

--- Round 2 of the storm Sunday night and Monday will feature possibly a surprisingly large amount of snow in the mountains, but the snow won't be as wet and heavy as tonight's. Total snow accumulation could reach two feet or more in some of the central and northern Green Mountains. 

Now the details: 

ROUND 1

It'll be a noisy night with gusty winds, rain in the valleys mixing with snow and maybe changing to wet snow later. Mid and high elevations are still for a big thump of heavy, wet snow, and the accompanying power outages overnight. 

Given how close temperatures will be to 32 degrees so there is a super high bust potential in the forecast for overnight and early Saturday.  Some areas might get much more snow than forecast, other area could get much less.

The National Weather Service said the best chances of a wrong forecast for overnight and early Sunday are in the Champlain Valley, and valley towns in central and northeast Vermont. 

Here's an example. Up in St. Albans, the National Weather Service is forecasting 5.2 inches of snow by 8 p.m. Monday. But there's a 10 percent chance it cold be 12 inches, but also a 10 percent chance of it being only 2 inches. 

We really won't know the results of the Round 1 snowfall until late Sunday morning, when the initial burst will be mostly done. In general, the National Weather Service is going with mostly snow above 1,000 feet in elevation overnight. And it could come down really, really hard.

That means snow will quickly cover roads, faster than the plows can keep up. Also, rapidly accumulating wet snow can make the power outages increase really, really fast. Stay off the roads overnight and early Sunday. Partly because of the compacted snow and ice on the roads. And partly because of fallen branches, trees and wires.

Especially when it's dark and snowing hard, you don't see those obstacles on the roads until you are on top of them.

One addition to the forecast is new wind advisory for parts of Addison and Rutland counties.

Downslope winds off the Green Mountains are now expected to be a bit stronger than earlier anticipated, and they'll probably gust to 50 mph, and possibly a little more in a few spots. That just puts more pressure on snow laden trees.  

The advisory helps underscore the issues with power outages we might have. Further north along the Greens, winds could gust to 45 mph overnight. I've already seen a gust to 39 mph in Burlington. 

Several recent storms have each cut power to more than 10,000 Vermont homes and businesses. I expect the same out of this one. 

Depending on how much rain falls, we could also see a bit of flooding. It's soggy out there, and warmer low elevations could really get quite a bit of rain before a changeover to snow or a mix. 

The Otter Creek in Rutland County almost reached moderate flood stage on Thursday, and has dipped just a little below minor flood state since. It's forecast to rise to minor flood stage again tomorrow afternoon or evening. 

The Winooski River in Chittenden County could flirt with flood stage, too, if there's enough rain, but it's unlikely to get as high as on Thursday, when low lying places like North Williston Road flooded. 

ROUND 2

The storm will seem to be largely over by noon Sunday. We'll just deal with cold rain drops in the valleys and light snows in the mountains. That will give crews a chance to begin repairing power lines. 

Snow will pick up again Sunday evening and go on through Monday The second dump of snow should focus mostly along and east of Route 7 and north of Rutland. Although the southern Green Mountains all the way to the Massachusetts border should share in the decent snowfall Sunday night through Monday night. 

This is a great setup for the western slopes of the Green Mountains and the summits. Some higher elevations might see an additional 12 to 18 inches. 

With round two of the storm starting later Sunday, I'm seeing some changes in when the most snow will fall in some areas of Vermont, especially in the northern Champlain Valley. 

Accumulations will range widely in western Vermont, with as little as one or two inches right along Lake Champlain and as much as six to 10 inches in places like Williston, Richmond, Westford, Fairfax and Fairfield. 

During the day Monday, the warmest valleys will go a little above freezing, which would limit accumulations, 

The Round 2 snow will mostly be more powdery than the cement like stuff we're expecting tonight. Still, winds gusting to 45 mph and additional snow loading should keep the power outages going Sunday night and Monday. 

Things will improve starting Tuesday, and we're still expecting a pretty serious thaw Wednesday through at least Friday.