Sunday, March 12, 2017

Big Winter Storm WILL Slam Northeast United States. Some Details Still Shaky

Here's a preliminary snowfall forecast issued Sunday
from the National Weather Service in South
Burlington for the upcoming nor'easter in Vermont
and northern New York. Click on the map to make it
bigger and easier to see. Looks like heaviest snow will
be east. Keep in mind the predicted snowfall totals
will almost definitely change between now and when
the storm gets here Tuesday. 

Not too much change so far to the forecast for the upcoming big storm in the Northeast. Most of the computer models are shifting the track of the storm a little bit with each run, but the oveall scenario remains basically the same.  

Still, there could still be some big busts in the forecasts. If the storm is closer to the coast, some areas near the water might get less snow and more rain than forecast.

If the storm shifts a little east, some inland locations will get less snow.

Winter storm watches have been upgraded to warnings across much of Pennsylvania, the southern half of New York, southern New England, and parts of Maryland and New Jersey.

Up here in Vermont, the National Weather Service in South Burlington says they've held off on upgrading the winter storm watch to a warning for now.

Most of the computer models put most if not all of Vermont in heavy snow Tuesday and Wednesday with this storm, but the American computer model keeps pushing the storm further east, which would limit snowfall in the Green Mountain State.

There's still time to see whether the American model will come on board with the other forecasts to determine whether we should upgrade to a warning in Vermont.

Again, snowfall forecasts are still tricky, but no matter what happens, it still seems likely the heaviest snow will come down in the southeastern half of Vermont.  It appears to be almost certain that it won't warm up enough anywhere in Vermont to worry about mixed precipitation or rain.


For what it's worth, here's the Weather Channel''s forecast
for snow in the Northeast, as of Sunday morning.
The forecast could still change, so stay tuned. 
I was impressed Saturday afternoon by how readily National Weather Service offices throughout the Northeast United States hoisted winter storm watches for this Tuesday.

They usually don't post such watches that far in advance of a storm, but the early alerts reflected the confidence forecasters have that a whopper of a snowstorm is heading toward the Northeast.

The blast of deep winter weather is already starting to cause loads of trouble, especially in the Southeast, where what had been an early spring is getting decimated by winter cold.

There's a lot to unpack here, so I'll start with how all this is playing out, and then, for my Vermont readers, I'll get into how this is all giving the Green Mountain State thrills and especially chills.


One ingredient to what is the insipient big nor'easter cut across the Tennessee Valley and into the Carolinas, dumping a coating of what is for them a spring snowfall.

It snowed in Columbia, South Carolina this morning, making it only the 17th time it has snowed in March there since 1888.

Meanwhile, another ingredient for the going-to-be big nor-easters is steaming eastward across the northern Great Plains and through the Great Lakes region.

Even though this northern piece of the would-be storm is fairly moisture starved, it's robust. Strong enough to prompt winter storm warnings in southern Minnesota and northern Iowa for four to nine inches of snow.

It's also going to snow in Chicago. Think about it: Basically no snow in Chicago all through January and February, and now an expected three to six inches of snow there.
A rather rare snowfall in South Carolina Sunday morning. 

That this northern piece is strong is a good hint that the big nor'easter will be, well, really big.


As we said, meteorologists are extremely confident of a huge, damaging nor'easter Tuesday and Wednesday. The devil is in the details.

The big cities of the Northeast- Washington DC, Philadelphia, New York and Boston among them, have a great chance of receiving six to 18 inches of snow with this. Maybe a little more in a few spots.

The storm could be particularly destructive toward Washington DC, where some trees and plants have already blossomed amid an early spring. The wet snow will collect on these new leaves and break lots of branches.

Additionally, strong nor'easters like this one almost always pull very cold air far to the south behind them once they depart.

That spells the danger of killing freezes over a wide area of the Southeast, which has already seen some cold weather damage this weekend.

I hope you don't like peaches. Some agricultural meteorologists expect 90 percent of the peach crop to be wiped out in the Southeast this week if temperatures get as cold as forecast. We're talking well down into the 20s. Maybe even upper teens.


The computer models are still struggling with how close the storm will come to the coastline, but as of this morning, there's more of a trend for an offshore track.

That would slam the coastal cities with lots of snow, and reduce the amount of snow well inland somewhat.

The New York City region, Long Island, southern Connecticut and coastal Massachusetts and Rhode Island are already under a blizzard watch for the expected heavy snow and strong winds.

The storm will have really wound up by the time it gets up near New England. There's still some questions as to how far inland from the southeast mixed precipitation and rain gets, but right now it appears it will stay all snow across New England, except on Cape Cod and the islands.

The nor'easter will almost definitely dump more than a foot of snow, cause damaging winds near the coast, and create coastal flooding and erosion in southern New England.


The Green Mountain State is going to be right on the line between heavy snow and lighter stuff. The southeastern half of Vermont is almost sure to get a very heavy snow, around a foot it looks like.

It will snow all over Vermont, but how much will fall over the northwestern part of the state is open to question.

I'm going to oversimplify things here in a very complicated forecast, but basically the European computer models take the storm slightly more offshore, which could limit snowfall in the northwestern part of Vermont.

The American computer model is slightly closer to the coast and predicts the storm will move more slowly, which would increase snow totals somewhat all over Vermont.

Another model, called the NAM, has the storm hugging the coast, putting Vermont in the sweet spot for some very, very heavy snow.

Both the European and American models are fairly reliable with nor'easters, and the NAM is only slightly less so, in  my opinion. My early guess is we might get closer to five inches of snow up in the northwestern tip of Vermont and close to a foot and a half in the southeast.

MAJOR CAVEAT: This preliminary forecast could change based on later information.

Given the strong chance of heavy snow anywhere in Vermont, the National Weather Service in South Burlington Vermont was smart to issue the winter storm watch for all of the state.

There will be tweaks to the forecast as more computer data comes in, and as the ingredients of the storm come together. Subtle differences in how these varying systems create the storm could make for big changes in the forecast.

It's Sunday. You've got until at least Monday night to make sure there's enough groceries in the house, enough time to figure out what to do if the schools are closed and the roads are a mess Tuesday.

Then sit back, and wait for updated forecasts. If meteorologist become sure there will be big snowstorm, they'll upgrade the watch to a warning, and we'll let you know.

On the bright side, it is going to warm up ever so slightly during the storm. It will remain much colder than normal for this time of year (Highs only in the 20s) but that's better than Saturday.

The high temperature in Burlington Saturday was just 11 degrees, the coldest daytime  high temperature on record for March 11. The old record was 14. Montpelier also set a date record for the lowest high temperature for March 11. It only got up to 7 above.

By the way, the cold spot in Vermont this morning was Walden, at 16 below.  Burlington got down to 0 Saturday and 4 this morning,  neither of which were record lows.

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