A winter storm expected to hit Greater Boston on Tuesday afternoon will drop a wintry mix of snow, sleet, and freezing rain on the region. But how much precipitation will fall? How much of it could land as snow? How about as rain?
The National Weather Service has issued a Winter Storm Watch for nearly all of Massachusetts, beginning Tuesday morning for the western part of the state and beginning Tuesday afternoon for Eastern Massachusetts. That warning extends through Tuesday night for Eastern Mass. and through Wednesday morning for the central and western parts of the state.
According to forecasts the weather service made early Monday, towns in Greater Boston are most likely to see 3-6 inches of snow during the storm, with precipitation turning into freezing rain Wednesday morning.
“Expect significant travel impacts, especially during the Tuesday afternoon into evening commute,” forecasters wrote. “Plan on slippery road conditions and reductions to visibility.”
The timeline of Tuesday’s storm
The storm is expected to roll into the region starting around noon Tuesday, with snow on its leading edge. Flakes should start falling around 3 p.m. in Boston, the weather service said in forecasts early Monday.
That snow may not last Wednesday, however — in a map produced Monday, the weather service predicted that the precipitation in the region by 1 a.m. Wednesday should be mostly rain and ice.
That wintry mix will form in large part due to temperatures that forecasters expect to slowly climb while precipitation falls. If the air temperature remains above freezing for longer, that precipitation is more likely to be sleet or rain, rather than ice or snow.
Precipitation should ease up starting in the early hours of Wednesday morning, although it could linger into the Wednesday commute, especially north and west of Boston.
Temperatures in Boston on Wednesday may linger in the 40s until sundown, and as a result, the city could see a slushy commute as fallen snow and ice melt.
Snowfall totals and possibilities
As of Monday morning, the weather service expects nearly all of Massachusetts to receive at least two inches of snow.
The North Shore and areas west of Interstate 495, however, are primed to receive more. While the storm still remains more than 24 hours out, forecasters predict the North Shore and towns west of 495 have the best chance of exceeding 4 inches of snow by the time things are all said and done with this storm.
How much is possible in an extreme case? Well, according to maps generated Monday, parts of the Pioneer Valley have a chance at up to a foot of snow if things take a turn, and Greater Boston towns west and north of the city could get eight inches.
Even if snowfall totals trend toward the high end, though, Boston is unlikely to get more than five inches.
And what if this storm’s a dud? Could the wintry mix remain rain- and sleet-focused and drop nothing in the way of snow?
It’s possible, but the weather service predicts that even in a very light snowfall, Boston should expect to get an inch, and communities in Central and Western Massachusetts could get 2-3.