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Here’s Dave Epstein’s early look at the possibility of a storm Sunday
"What I can say now is that the most likely areas to see significant snow will be Cape Cod, the Islands, and perhaps Southeastern Massachusetts, with lighter amounts possible for Greater Boston."
It’s already the middle of the week and time to take a closer look at the weekend forecast — and the possibility of a storm on Sunday.
Before we get to the possibility of snow and wind on Sunday, we have to suffer through a very cold day to start the weekend Friday.
Temperatures during the day Friday will start near zero or in the single digits and will only recover to between 12 and 19 degrees in the afternoon. It will be coldest in the Worcester hills and across Northern New England, where some ski areas will stay in the low single digits all day long.
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When you add in the wind on Friday, wind chill values will be below zero, but if you dress properly you can definitely get outside for a short walk and take in some of that brilliant sunlight. The sun this time of the year is getting stronger each day and is now equivalent roughly to the middle of November. Not suntan weather, but a little bit better than late December.
Friday night is likely the coldest night we’ve seen so far this winter. Even Boston could get close to zero, and the suburbs are likely to go several degrees below zero.
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(This won’t be cold enough for damage to the fruit trees because the absolute low temperature won’t be cold enough, and it’s been consistently cold this winter so those buds are as tight as they get this time of the year.)
On Saturday, skies will cloud up and it may look like snow by the end of the day, especially south of Boston, but there will not be any precipitation. Temperatures will reach near 20 degrees — a little bit better than the prior day but still 15 or so degrees below average for the time of year.
Saturday night features cloudy skies, and the breeze may pick up a little, especially over the Cape and the Islands, as a developing ocean storm east of the Carolinas gets even stronger. It’s at this point that the gradient between high pressure well to our north and that storm out in the Atlantic gets more intense.
Nor’easter: Potential for coastal flooding, damaging winds
On Sunday, this storm will be moving northeast into the open Atlantic. It will likely reach its maximum intensity during the day Sunday or perhaps Sunday evening before moving farther to the east and slowly weakening.
We’re going to be on the western side of this developing nor’easter with the snow shield reaching toward Southern New England. Just how far west the accumulating snow gets, I cannot tell you at this point, since the storm is still four days away.
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What I can say now is that the most likely areas to see significant snow will be Cape Cod, the Islands, and perhaps Southeastern Massachusetts, with lighter amounts possible for Greater Boston.
Bombogenesis will occur with this storm
This storm is expected to undergo what we call “bombogenesis,” or rapid strengthening, off the East Coast before reaching our area. We’ve got two pieces of energy diving down, one on the northern jet stream and one on the southern jet stream. They’re going to meet and create bombogenesis, meaning a storm intensifying by at least 1 millibar per hour for 24 hours.
So, with a 24-millibar drop, the more the pressure drops, the greater the intensity of the storm. And the gradient between the center of the storm and everything around it gets bigger. The air has to rush into that storm to fill that gradient, and the result is lots of strong, gusty wind.
Seeing the full fury of the storm at this point is not likely, but we’re not beyond that threat either. If trends start moving the storm farther west, then we’ll have to plan on a much bigger impact.
On Monday, it’s back to sunshine and cold weather, although the cold may relax a bit next week.
Weekend breakdown
Greater Boston: Look for sunny skies to dominate Saturday with temperatures near 20. Some snow is possible on Sunday with temperatures in the 20s.
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Central/Western Mass.: Sunshine followed by increasing clouds on Saturday with highs in the teens. Cloudy skies could yield some light snow late in the day on Sunday, with highs near 20.
Southeastern Mass.: Skies will be sunny on Saturday with temperatures in the 20s. It is breezy with a good chance of at least some snow on Sunday, with highs in the 20s.
Cape Cod and the Islands: Look for mostly sunny skies on Saturday followed by clouds and temperatures in the 20s. Snow is likely Sunday evening, with temperatures approaching freezing. It will become windy.
Rhode Island: Look for sunshine followed by increasing clouds on Saturday. Temperatures in the 20s. Chance of snow on Sunday and breezy.
New Hampshire: Look for plenty of sunshine on Saturday with highs in the teens. Sunshine on Sunday, followed by clouds and maybe snow over southern areas.
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