A lot of clouds will be in the sky today, but it’s going to be mild. Portland reached 64 degrees just after midnight and this means today, like yesterday, will have a record high temperature in the books. If someone looks closely years from now they might think it was funny we went from record highs to snow in such a short time, but this is Maine and these things happen.

Overview
A low-pressure system is going to develop along the coast and move northward as a nor’easter. This storm will bring the typical weather associated with a storm on this track. The heaviest snow is usually inland around the foothills with the coastal plain fighting the warm air off Casco Bay and the Gulf of Maine. The image below from the folks at the National Weather Service tells the overall story quite well.

Timing
The precipitation will fall mostly from about 9 a.m. Wednesday until about 2 a.m. Thursday. The strongest wind will be later Wednesday and Wednesday night.

The image below shows projected radar around 1 p.m. tomorrow. Notice the blue area; this is where it is forecast to be snowing. The exact position of the rain/snow line will likely fluctuate with areas west of the Maine Turnpike seeing the most snow.

The precipitation winds down very early Thursday morning. The next image shows the radar at around 1 a.m. on Thursday. Notice that the precipitation by then is ending south of Portland and this back edge will move steadily north before sunrise.

Snowfall
The forecast is based on the predicted position of the boundary of something meteorologists call the coastal front. Below I have drawn where I expect the coastal front Wednesday evening at the height of the storm. If the front is 10 miles farther west or east it will dramatically affect the amount of snow forecast.

To the east, or right side, of the front marine air will keep the precipitation mostly rain. These areas could see a bit of slush at the end of the storm, but it’s mostly a rain event. To the left of the front, we have a rain-to-mostly-snow situation. The earlier the rain changes to snow, farther west, the more snow you will have by the end of the storm.

I have seen a 4- to 5-inch difference on either side of a coastal front. In one storm in the late ’80s the Portland Jetport recorded just 2 inches while I had over 6 in North Deering.

Here’s a closer look. I have tried to pinpoint the totals more along the coastline.

Travel
The Portland Jetport will see delays. I don’t expect this is a situation where the airport closes. Flights in and out of Burlington, Vermont, Manchester, New Hampshire, and Boston will be impacted by the snow, rain and wind.

Amtrak trains run close to the coast and this storm, even if it’s all snow, won’t be enough to halt operations on the rails.

Highways will be wet initially as the snow begins. As the snow comes down harder and harder secondary roads will become snow covered and then the highways. If you do need to travel tomorrow afternoon and you have a choice which roads to take, try to stay closest to the coast.

The entire storm will be over well before sunrise Thursday and that day will be cold and a bit blustery with some sunshine breaking through the clouds.

Other Factors
When I make my snow predictions it’s for the grassy surfaces. What you end up shoveling might be quite different. The roads have quite a bit of heat built up from the past few days of warm weather, meaning the first inch or two or even more could melt on the road before it starts to accumulate and need to be shoveled.

Another factor in what you’ll see on your lawn and in the official total numbers is that the ground won’t be frozen when the snow begins and the snow will melt a bit from the bottom up as it accumulates.

Could We Get More?
I am quite confident with the snowfall prediction for areas west of the Maine Turnpike. The hardest part of the forecast is for those areas along the coast and places like Peaks, Bailey and Mount Desert Island. These areas can stay mostly rain while there is quite a bit of snow just a few miles inland.

I’ll be updating on Twitter and here as I receive new data.

Follow @growingwisdom

Copy the Story Link