[SCROLL DOWN FOR UPDATES] The National Weather Service has issued a Winter Storm Warning for the tri-state region, with heavy snow and extreme winds expected in NYC starting Sunday evening and possibly continuing through early Tuesday morning.

On Sunday night, Mayor Bill de Blasio ordered all non-essential traffic be restricted staring at 6 a.m., Monday, to keep people off the road.

Essential services like first responders, public transit, food delivery, utility workers, and homeless outreach, are are allowed:

“Make no mistake: this storm will bring heavy snowfall, and it will make travel dangerous in every neighborhood in our city,” said Mayor Bill de Blasio in a statement. “New Yorkers should stay home, keep the roads clear for emergency vehicles, and let our plows work to keep us all safe. This order will be mandatory at 6:00 a.m. tomorrow, and everyone should make necessary preparations this evening.”

Earlier in the day, NWS forecast predicted 17 inches of snow is likely to bombard NYC, with a 1-in-10 chance we could see 22 inches of snow.

There is also a chance of coastal flooding in parts of Queens around Jamaica Bay during high tides on Monday.

Blizzard conditions are expected at times during the day and night on Monday in the city and coastal areas. Extreme winds of 20 to 30 mph are forecast in NYC, with gusts of 40 to 50 mph.

The precipitation could turn to sleet later on Monday as temperatures rise to an expected high of 34. But if the mercury stays below freezing, there's greater potential for accumulation on the high end of the forecast.

"Much of the Jersey Shore, Long Island and New England coast could remain just cold enough at all levels of the atmosphere to stay all snow through the storm," said AccuWeather Meteorologist Brett Rossio.

The impending Nor'easter is the second to hit NYC this winter, following a snowstorm in mid-December that dropped more than a foot of snow on the city -- the first major snowstorm in several years.

The current NWS prediction calling for over a foot is rare -- according to NWS, only 36 storms since 1869 have delivered over 12 inches of snow in Central Park.

Governor Andrew Cuomo has instructed state agencies to prepare "all emergency response assets" in advance of the expected blizzard.

The MTA and Sanitation Department, which is responsible for snow removal in NYC, are holding press conferences this afternoon to update New Yorkers on snow preparation plans. We'll update here with new information as we get it.

UPDATE 10:46 a.m.:

At a press conference Sunday morning, Mayor Bill de Blasio said in-person classes at NYC public schools will be canceled on Monday, warning that the city is bracing for a major snowstorm. Of course, that doesn't mean kids get a snow day -- in the time of COVID-19, all public school students will be expected to attend class remotely.

De Blasio also announced that all COVID-19 vaccination appointments would be canceled on Monday and rescheduled. Tuesday vaccine appointments are currently still in place, though the mayor cautioned that this could change depending on the storm.

Food distribution sites and the Learning Bridges pandemic childcare program will be canceled on Monday. And outdoor dining in city streets will not be permitted on Monday, in order to facilitate snow removal efforts.

The city's Code Blue emergency cold weather plan is in effect, with outreach teams working to homeless New Yorkers get shelter.

UPDATE 4:21 p.m.: The National Weather Service has revised its forecast from this morning and now anticipates between 18 and 24 inches of snow to fall over the next 36 hours in NYC. A very light snow is currently falling in parts of Brooklyn, but snowfall is expected to be heavy overnight.

Long lines formed outside some supermarkets in NYC on Sunday as New Yorkers hastened to stock up on food before the blizzard. Here's the scene outside the Key Food on Avenue A and 4th Street in Manhattan this afternoon:

The line outside Key Food on Avenue A and 4th Street at 4 p.m. on Sunday.