LOWELL -- Snow will start falling slowly later tonight and Thursday, but then build to nearly blizzard conditions by early Friday morning, as forecasters anticipate a Nor'easter will bring 10 to 14 inches of snow and potentially dangerous wind chills to the Merrimack Valley.

Starting tonight and throughout the daylight hours on Thursday, snowfall will be relatively light, with perhaps an inch of snow on the ground by Thursday morning, and perhaps 2 or 3 inches by the Thursday afternoon commute, according to Eleanor Vallier-Talbor, a meteorologist at the National Weather Service in Taunton.

But that's not the end of the story of this Nor'easter.

"This is a long-duration event, and it's kind of coming in two pieces," Vallier-Talbot said.

There could be a bit of letup in the snow Thursday afternoon, but that will be followed by rapidly falling snow, high winds and bone-chilling temperatures that will make travel, or even being outside, hazardous from Thursday night to Friday morning.

Winds will be gusting at up to 30 mph as snow falls at an expected rate of 1 to 2 inches per hour late Thursday into Friday morning, possibly overwhelming the ability of plow crews to keep the streets clear.

"It will be nasty," said Vallier-Talbot. "It's not going to be very good."

She said visibility at the height of the storm early Friday could be as low as a half mile to a quarter mile, as winds whip the falling snow in single-digit temperatures.

Add high winds to those low temperatures, and the wind chill on Friday could approach minus 15, the point at which the National Weather Service begins issuing wind chill advisories to help keep residents safe.

The storm is not expected to be a blizzard, since sustained visibility of less than a quarter-mile is required before a storm is considered a blizzard by the National Weather Service.

Vallier-Talbot described the conditions this storm will bring as "near-blizzard conditions."

Lowell Public Schools and the Greater Lowell Technical High School have already canceled classes on Thursday and Friday, and other closings were begin to trickle in on Wednesday night.

City Manager Bernie Lynch said road crews would begin pre-treating roads in Lowell on Wednesday night, and then begin major plowing operations as the snow builds up.

He urged everyone to remain patient, since the duration of this storm will force some plow drivers to rest, for safety reasons, as they battle to keep roads clear over a storm that will last 24 to 36 hours.

He urged everyone in Lowell to get their cars off the street, and said the city will soon announce a snow emergency parking ban and inform residents when the Ayotte and Early parking garages will be open for residents to park for free.

"The more cars that are off the road, the easier we can plow," Lynch said. "Hopefully people will be patient and help us out as we go along."

Vallier-Talbot said that the wind chill will drop even lower once the snow is finished on Friday night.

She said another batch of arctic air will move into the region as the snow stops falling, dropping temperatures to about minus 5, and wind chills as low as minus 16 or 17.

With the wind-chill that low, anyone who leaves skin exposed while outside or shoveling could face serious danger.

"It won't take long at all for (exposed skin) to get frostbite," said Vallier-Talbot.

Lynch said city leaders will meet in the Emergency Operations Center on Thursday to discuss other steps, which may include opening the Lowell Senior Center as a shelter.

The city will also work with police, firefighters, EMS crews and the Lowell Transitional Living Center in an attempt to keep the homeless population safe.

Vallier-Talbot encouraged people to protect both themselves and their pets from the cold, since the low wind chills will leave outside pets in danger.

She also suggested wearing layers of clothing, and avoiding the consumption of alcohol if you're going to be outside.

"Drink non-alcoholic beverages," she said. "Alcohol makes you feel warmer even though you're not, but drinking nonalcoholic beverages actually helps keep your body a little bit warmer."

For updates on storm warnings and advisories, follow the National Weather Service on Twitter @NWSBoston. 

Follow Robert Mills on Twitter and Tout @Robert_Mills.