The first widespread winter storm for New England is going to move into the region this weekend, bringing with it all kinds of forecasting headaches and the first widespread plowable snowfall since last winter.
Unlike the last few snow opportunities, a very cold arctic air mass will be in place at the onset of the storm, ensuring precipitation starts as snow, rather than rain.
In fact, over interior regions of Southern New England, away from the marine influence, it’s likely that temperatures are in the 10s when snow starts Saturday afternoon.
Along the coast, even here on the Cape, we will likely be in the 20s as snow breaks out (which will likely happen a bit earlier thanks to some ocean effect snows drifting in off the water) during Saturday.
However, despite the bitter cold temperatures Saturday morning, this is not and ideal set-up to keep temperatures cold throughout the storm. Milder air will try and fight its way into the region Saturday night as the arctic air and its associated high pressure center drift eastward away from New England Saturday Night and Sunday.
As a result, temperatures will warm – both at the surface and aloft – with time Saturday night, with above freezing air making gradual inroads westward and northward across Southern New England.
Now, over the distant interior, the warm air will almost certainly lose out, and all of the precipitation should fall in the form of snow. The dense cold air will be nearly impossible to scour out of those locations.
But the further south and east one travels, the deeper the column of warmer air will become. In some areas, this column of warmth will only be thick enough to produce some periods of sleet toward the end of the storm.
However, closer to the coastal plain, this milder air will almost surely lead to a mix of sleet and freezing rain, with plain rain developing along the coast from Boston to Plymouth and down to the Cape.
In fact, here on the Cape, I would not be surprised if temperatures jump to the middle or even upper 40s for a short-time Sunday morning as mild air surges in on strong southeast winds.
Here is a look at the current snowfall forecast: