Here’s David Epstein’s lookahead to Wednesday’s snow

Preliminary snow totals look to be heaviest west of Interstate 495 and north of the Mass. Pike.

SNOW SLIDER1 Boston, Massachusetts - 1/4/2018  -  A woman walks through the snow as it falls in Boston, Massachusetts, January 4, 2018. (Keith Bedford/Globe Staff)
A woman walks through snow in Boston, Jan. 4, 2018. –Keith Bedford / The Boston Globe, File

A winter storm watch has been posted for Wednesday afternoon and night for interior southern New England as our next storm system approaches from the south. The energy for the storm is just now becoming better understood by the computer models, so the forecast is still subject to quite a bit of variability. The biggest challenge over the next 24 hours will be to determine exactly where the rain-snow line will end up — and at what time the changeover occurs.


A burst of snow then rain moves into southern New England Wednesday. Credit: COD Weather

This particular storm has a lot of moisture and a difference of just two or three hours in terms of snow changing to rain would be the equivalent of that many inches as well. This is going to be a heavier and wetter snow, and, with the change to rain, it’s only going to become even more difficult to move as time goes on Wednesday afternoon into the night. This means you should try to remove the snow as soon as possible during the change to rain.

Preliminary snow totals look to be heaviest west of Interstate 495 and north of the Mass. Pike. —David Epstein

I don’t expect the Wednesday morning commute to be impacted. However, the Wednesday evening commute could be a very big mess. If the snow arrives early enough on Wednesday, there will likely be some cancellations or early dismissals from schools and businesses. This isn’t a big nor’easter but where it stays all snow the potential exists for 6 to 12 inches, most likely into southern New Hampshire, Maine, and much of Vermont.  

Logan airport won’t shut down or anything along those lines, but some flights likely will be delayed or canceled during the middle of the day Wednesday.

We’ll get a pretty good burst of snow during the middle part of Wednesday with accumulation rates approaching an inch an hour for awhile.

The moisture equivalent from the snow and rain will equal about an inch of water. This is quite heavy for February. —WeatherBell

This storm is part of a series of storms that is going to be affecting New England over the next two weeks. I’ve written about the fact that winter isn’t over and an active jet stream seems very likely through the middle of the month. The challenge with these upcoming systems is going to be the rain-snow lines and the amount of cold air in place during them.

The probability of a wetter than average mid-February is highest over New England. —NOAA

It’s not surprising that we’re getting a storm this week. We’ve had snow the first two weeks of February for the past several years, and, of course, this week is also the 40th anniversary of the Blizzard of 1978. Climate normals are calculated over a 30-year period, but it’s of interest that, since 2000, February has been averaging snowier than January. Of course, the February two years ago skewed the average a bit.



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