The storms is expected to build up late Friday, and continue overnight, with wind and continued snow or ice lingering as a travel concern on Saturday.
Winds in the region are forecast to include gusts up to 75 miles per hour. That, coupled with the potential snowfall and some freezing rain, could ground aircraft, stall commuters, and complicate railroad operations across the region.
It also makes for a significant risk of power outages.
A Weather Service alert for the Boston area says snow will start to develop Friday morning, shifting to rain during the afternoon. “The rain will change back to wet snow sometime Friday night, and continue into Saturday afternoon.”
In Boston, Mayor Thomas Menino showed by mid-day Thursday how seriously the region is taking the storm. The city announced that schools would be closed Friday, declared a snow emergency and put a parking ban in place for noon Friday, and said only "essential" workers should show up at City Hall.
Via Twitter, the city warned of a “historic winter blizzard,” although it’s possible accumulations in the city will end up closer to 10 inches than 20.
The storm, dubbed Nemo, comes just a few months after the New York City area was hit by Sandy, the so-called superstorm that brought significant floods and power outages.
“We’re ready for #Nemo, the office of New York City Mayor Michael Bloomberg said on Twitter. “We have 250,000+ tons of salt on hand, 350 salt spreaders & plows ready to be put on 1,800 Sanitation trucks.”