BOSTON (CBS) – Our Saturday snowstorm is right on track with the majority of the snowfall coming with a "front end thumping" during the morning hours.
There will be three "chapters" to this storm. The morning will have a widespread thump of snow followed by a surge of warm air that changes the snow to rain as far north as Route 128 and Interstate 495 in the early afternoon. Finally, there will be a change back to snow everywhere before tapering off this evening.
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WHAT TO EXPECT
Chapter 1: The Front End Thump
4 a.m. – 10 a.m.
Sounds like the newest dance craze right? This is a common occurrence with winter storms here in New England.
The greatest atmospheric lift is with the beginning part of the storm, leading to the heaviest precipitation and greatest snow totals in the first several hours. About two-thirds of the snow for the entire event will occur in the first six hours. Road conditions will deteriorate quickly, likely the worst driving conditions all day. A solid, widespread 2-4" will be on the ground for all of Southern New England by 10 a.m.
Chapter 2: The Warm Air Invasion
10 a.m. – 3 p.m.:
Warmer air moves in later in the day and snow changes to sleet and rain, first along the South Coast and very quickly northward to around the Mass Pike. Both Boston and Worcester should be mixing with sleet and rain by late morning or midday.
The mixing line could reach as far north as I-495 around 2 p.m. Snow will continue north and west of I-495 and Route 2, but there will be a sharp cutoff on the far northern edge of the precipitation shield. Very little if any snow is likely to fall north of Manchester, N.H. and southern Vermont. Very little snow accumulation will happen during these hours as this warm surge will also come with a relative lull in the precipitation. An additional coating to two inches north and west of Boston through 2 p.m.
Chapter 3: The Snow Strikes Back
3 p.m. – 9 p.m.:
Winds will begin to veer to a more north-northwest direction, drawing in colder air and changing any rain and mix over to all snow from north to south. At the same time, the back edge of the precipitation will start moving west to east. The intensity of the precipitation will pick up once again and we expect an additional 1-3" of snow in most areas before tapering off.
Approximate end times:
Fitchburg andWorcester: 6 p.m.
Metro West, 495/128: 7 p.m.
Boston & Immediate Coastline: 8 p.m.
South Shore: 9 p.m.
Cape Cod: 10 p.m.
Cape Cod and Islands:
Mainly rain, coating to an inch possible at the tail end.
South Shore, inland southeastern Mass.:
Accumulation of about 2-4 inches.
Right around 3 inches, but it depends on how much warming we get and how long it sticks around. Very wet and sloppy. This would be the biggest snowfall in Boston in nearly a year.
North and West, 128 to 495 to Route 2, including most of Essex, Middlesex and Worcester counties, southeast New Hampshire and southern (coastal) Maine:
Four-to-8 inches of snow. Potential for a bit more, up to 9 or 10 inches with some locally heavy banding.
Southern Vermont, central New England:
Two-to-4 inches of lighter precipitation, near the northern edge.
Northern Ski Areas:
Sadly not much here, just some flurries.
This system will be rapidly deepening and strengthening as it passes south of New England. Therefore, we do expect the winds to play a role along the coast and over Cape Cod and the Islands.
Gusts should reach between 30-to-50 mph Saturday night, strongest as the storm is passing by late. There could be some minor wind damage or isolated outages in these locations.
Again, since the strongest winds will be on the backside of the storm they would be out of the north/northwest, generally an offshore direction, other than in Cape Cod Bay.
Not a major concern with this storm due to the fast movement.
Some pockets of minor coastal flooding are possible during the Saturday afternoon high tide (around 2:30 p.m.). The winds will have turned mainly offshore by the following high tide (around 2:30 a.m. Sunday).
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