The National Weather Service said Tuesday a new nor’easter will arrive as expected Wednesday, bringing thundersnow, rain, high winds, and 17 or more inches of snow to Central and Western Massachusetts. But early predictions of heavy snowfall for Boston began evaporating as Tuesday progressed and more definitive weather models were created.
The city and its immediate suburbs are expected to get mainly rain, with 1 to 3 inches of snow. Pockets of the Metrowest region are expected to receive up to 6 inches of snow before the system wears itself out in the predawn hours of Thursday. The nor’easter, the second in a week, will affect the Wednesday evening and Thursday morning commutes.
“Latest forecast model guidance suggests a storm track that will lower snow amounts inside [Interstate] 495 and the [southeastern/northeastern] coastal plain,’’ forecasters wrote Tuesday afternoon, urging people to stay tuned.
In other parts of the state, the snow will be falling up to 3 inches per hour Wednesday evening, forecasters wrote.
“This amount of snow in a short amount of time will make travel difficult and result in very low” visibility, forecasters wrote. “Expect the Wednesday evening rush hour to be significantly impacted.”
Precipitation is expected to reach Worcester by 11 a.m., Boston by noon, and Cape Cod by 1 p.m., according to the Massachusetts Emergency Management Agency.
The system is expected to be its most turbulent in a massive chunk of the state that stretches south from Newburyport to Foxborough and west through the Worcester Hills. Snowfall estimates are 6 inches for Newburyport and Bedford, 3 inches for Foxborough, and 17 inches — or more — in Fitchburg.
Cape Cod and the Islands and Southeastern Massachusetts are expected to have little or no accumulation, with those areas experiencing mostly rain.
With both coastal and inland communities still reeling from the flooding and powerful winds that knocked down thousands of trees statewide, forecasters said winds will once again reach 60 miles per hour, especially along the coast.
Forecasters — and municipal officials — are worried that the trees weakened by Friday’s storm will be knocked down either by winds or the weight of snow, which is expected to be heavy and wet, especially along the coast.
Some flooding is possible along rivers and the coast, but forecasters said they do not expect the same dangerous conditions that flooded downtown Boston, damaged sea walls, and led public officials to condemn some flooded homes.
MEMA anticipates that the snow will change to rain Wednesday evening in much of Eastern Massachusetts, with the rain/snow line expected to be north and west of the Interstate 95 corridor.
Forecasters caution that if the line between rain and snow shifts, snowfall totals could change dramatically. But they are confident the I-495 corridor will get around 6 inches of snow, and a winter storm warning has been issued for that area, taking effect at 7 a.m. Wednesday, forecasters wrote.
State transportation officials are encouraging the public to avoid traveling during the snowstorm. Jonathan Gulliver, highway administrator for the Massachusetts Department of Transportation, said the public should consider working from home or postponing travel. He said residents should take public transit when they can.
State crews are pretreating roads with brine and magnesium chloride.
In Boston, the MBTA will replace the Mattapan trolley service with shuttle buses for the duration of the storm, starting at 11 a.m. Wednesday.
The T plans to operate a regular weekday service on the Red, Orange, Blue, and Green lines on Wednesday and Thursday. Ferry service will also operate on a regular schedule those days, according to the MBTA.
Regular bus service is scheduled but depending on the snow, some buses may operate on designated “snow routes,” according to the T.
Amtrak on Tuesday said it was canceling some trains on its Acela Express, Northeast Regional, Keystone Service, and Empire Service lines in preparation for the storm.
The MBTA plans to operate some nonpassenger trains early Thursday morning to keep tracks clear and to look for any trees or branches, according to a statement from that agency.
Emergency crews will be on standby “throughout the storm to respond to instances of broken rails, issues affecting the power systems, potential switch problems, and any water-related issues that may occur.”
In Fitchburg, where forecasters are predicting 17 inches of snow, Mayor Stephen L. DiNatale said crews were out Tuesday pretreating roads. The city has 25 pieces of snow-clearing equipment and can also use an additional 75 pieces of snow equipment through contracts, he said. He anticipates around-the-clock plowing for the duration of the storm.
“We’ll have all hands on deck,” he said.
A parking ban on the city’s streets will go into effect at 3 p.m. Wednesday, he said. The city’s hilly topography presents a unique challenge for road-clearing crews, DiNatale said.
“We have one of the hilliest communities in the Commonwealth and arguably in the country,” he said.
Daytime temperatures Wednesday will be in the 30s across the state and remain in that range overnight into Thursday in Eastern Massachusetts. On Thursday, as the storm ends, daytime temperatures will reach around 40, and Friday will bring similar temperatures, said Joe DelliCarpini, a meteorologist with the National Weather Service in Taunton.