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| The very latest snow accumulation forecast map from the National Weather Service office in South Burlington. They've trimmed back snow totals slightly compared to this morning's forecast, but this storm is still going to have a lot of impacts. |
Those north winds are making temperatures start to fall, but it won't get cold enough for snow until midnight or a little after in the Champlain Valley and in the wee hours of the morning further east and south.
As was inevitable, there have been some subtle changes in the forecast. That will continue through the duration of the storm.
There probably will be a few surprises one way or another somewhere in Vermont. Anything you read for the rest of this post isn't cast in stone. All winter storms throw curve balls at us.
The trend in the forecast late this afternoon has fortunately been to lower the snow totals just a bit compared to this morning's forecast. I don't know if that's part of a welcome trend that would lower the impacts of the storm, or just a minor last minute adjustment based on the latest computer models.
Though slightly less snow would mean slightly less snow loading on trees and power lines, that shouldn't matter too much. I still expect quite a few power outages on Monday pretty much statewide.
Unlike in the last two storms, lower elevations might have the biggest problems with power outages on Monday. Not as much snow will accumulate in the valleys compared to the mountains. But the valley snow will be particularly wet and slushy - that wet cement I keep talking about.
I'm getting ahead of myself. Let's take it a step at a time, chronologically, as I did this morning.
RAINFALL
So far, this afternoon's rain hasn't been too intense. As of 5 p.m., rainfall in Vermont seems to be around a quarter inch so far, give or take. The rain will probably pick up in intensity this evening, but the flood threat has really gotten low.
At least here in Vermont. Eastern and southern New England are in the cross hairs for some possibly significant flooding. Vermont's problem remains snow.
Some towns in Vermont could get an inch of rain before things switch over to snow. Since the switch-over will be later in southeastern Vermont and that part of the state is going to be in deeper moisture from the storm, rainfall totals will be higher there, so as a precaution a flood watch remains in effect for southern Vermont.
SNOWFALL
The central and northern Green Mountains continue to look like they will be in the sweet spot for snow. Those areas are in for a foot, maybe a foot and a half of snow. Which will be great for the ski areas, as snow lost in the thawing today will mostly be replaced.
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| Dark and rainy in downtown St. Albans, Vermont Sunday afternoon. By dawn tomorrow, this same scene will' look very, very snowy. |
Snow accumulations in the valleys are harder to predict, because it depends upon on how "warm" it stays through this, and how long the heaviest snow rates last.
When the snow comes down really hard, it tends to cool the air a bit so that it sticks better. When the snow is lighter, temperatures could bump up to just above freezing, limiting further accumulations.
Unfortunately. the heaviest snow looks like it will come between 2 and 10 a.m. Monday.
That would give snow plenty of time to accumulate ahead of Monday morning's commute, and continue to pile up quickly when people are trying to drive to work.
Power outages will likely be rapidly ramping up during this time, too, as heavy, wet snow accumulates fast.
The National Weather Service in South Burlington says that predicting how much snow will pile up is especially tricky in the Champlain Valley. They expect a sharp gradient between the immediate lakeshore and the foothills of the Green Mountains to the east.
The immediate shore of Lake Champlain might only get two to four inches of slush.
Along and just east of Route 7, at this time the expectation is four to eight inches. Once you get into eastern Chittenden and Franklin counties, we're talking close to a foot.
Overall, the biggest adjustment to snowfall forecasts is in the Champlain Valley. Forecasts broadly call for five to nine inches in places like Burlington and St. Albans. That's three or four inches less than what the forecast called for this morning.
That said, those cities could still get socked with more snow than that, or they could be pleasantly surprised with less. Flip your coins, boys and girls, it could go either way.
Just as in the last two storms, temperatures will be marginal, within a degree or two either side of the freezing mark. The last two storms favored snow in mid and high elevations. This time, the valleys are in play. But if the temperature winds up a couple degrees warmer than expected, the snowfall forecast is a bust, and only a few inches will fall.
If it's a bit cooler than forecast, the snow will be deeper. But it would be marginally less wet and sloppy, which would help the power line issues.
It's still looking like southern Vermont won't be as bad with the snow with this system, but higher elevations can expect a good six inches of snow with power failure risks there, too. The lower Connecticut River valley floor looks pretty safe from any major snow accumulations.
Bottom line: Expect a real mess pretty much statewide Monday morning. My advice from this morning still holds: If you can stay home Monday morning, then stay home. Call in sick if you have to. If your boss whines, blame me.
Power up your devices this evening, and drag out those LED candles in case you'll need them Monday morning. Unfortunately, this is the type of storm that could lead to some people being without electricity for a couple or even a few days.
The good news in that department is it won't get super frigid after the storm passes Monday evening. High temperatures Tuesday through the end of the week should be more or less in the 30s, with lows in the upper teens and 20s.
Yeah, that's chilly. But at least it won't be below zero, so your pipes have a shot at not freezing and bursting if you lose power for a few days. After all, it could easily get below zero this time of year. But in this instance, it won't.
After this storm goes by, the weather will get mercifully quiet for a few days at least. A weak storm and cold front might dust us with an inch or two of snow Tuesday night or Wednesday, but that's no big deal.
Temperatures are also forecast to stay at or above normal well into mid-month and possibly beyond, so that's nice.
By the way, this all could be worse. Around this time in 1952, a similar storm struck Vermont, but it was more intense than this one.
Temperatures started out in the 50s with quite a lot of rain on December 11, 1952. Then it got sharply colder, but temperatures bottomed out at around 32 degrees late on December 11 and during the day December 12.
The end result in Burlington was 2.75 inches of rain and melted snow and 13.4 inches of heavy, wet snow. Two feet of wet snow buried St. Albans. Rain and melted snow amounted to 3.25 inches in St. Albans, more than normally falls in the entire month of December.
I doubt this episode will be as bad as 1952. I'm always looking on the bright side, right?
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