A nor'easter is soaking the coast. Who could see the first snow of the season?

Snow is likely to fall in the mountains of New York and northern New England Thursday night as a storm system — aka a developing nor'easter — currently dumping rain across the Mid-Atlantic moves north and encounters colder air from the north.

The National Weather Service's Weather Prediction Center (WPC) said in its latest forecast that as the colder air wraps around the storm, rain will turn to snow overnight into Friday at higher elevations in New York, northeastern Pennsylvania and northern New England — likely making the roads hazardous.

Those at lower elevations will mostly see rain through Thursday night, with a wintry mix possible Friday morning. Wet snow is also possible in the southern and central Appalachians, mainly from Friday night into Saturday morning — some areas could see their first snowflakes of the season.

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In Michigan's Upper Peninsula, heavy lake-effect snow will bring "significant accumulation" through Friday, the WPC said.

The nor'easter is expected to strengthen as it moves into the Northeast through Thursday evening, after bringing scattered thunderstorms and gusty winds to the Ohio and Tennessee valleys earlier in the day. Its center is expected to pass east of Cape Cod.

Steady rain is expected to spread over southern New England Thursday evening, possibly becoming heavy at times near the coast, according to the WPC, which also forecasts increasing northeasterly winds and minor coastal flooding around high tide near New York City.

Following the storm, polar air will then spread across much of the central and eastern U.S., with temperatures well below normal by Friday. Freezing temperatures are forecast to reach the Deep South by Saturday morning, setting up a widespread frost and freeze across the South and Southeast this weekend.

Is snow likely?

Mostly in the mountains. The WPC said rain will turn to snow Thursday night and into Friday at higher elevations in New York, northeastern Pennsylvania and northern New England, where accumulating snow is likely.

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AccuWeather said Pittsburgh, Syracuse and Binghamton could see their first snowflakes of the season, along with the Poconos, Catskills and Berkshires. Wet snow is also possible in the southern and central Appalachians from Friday night into Saturday morning, the WPC said.

But AccuWeather senior meteorologist Adam Douty said, "outside of higher elevations, snow should struggle to accumulate."

As it stands, most coastal areas and lower-lying parts of the Northeast, including Philadelphia, New York and Boston, are more likely to see rain than snow.

Is the nor'easter linked to the polar vortex?

The early weakening of the polar vortex, which started last week, has left many wondering whether a blast of icy weather is on its way as a result. But forecasters have said it's not that clear.

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While the WPC's latest forecast refers to polar air, meaning a mass of very cold air from Canada, it doesn't mention the polar vortex.

Tyler Roys, a meteorologist at AccuWeather, told Yahoo it is "hard to say if there is any connection between the two." He said most of the impacts from an early polar vortex disruption are "going towards eastern Europe and Asia."

If the vortex has any influence, Roys said, it is likely tied to the cold arriving behind the storm, though "the influence of the polar vortex appears to be limited."

Roys added that forecasters "do feel that there could be an increase of influence from the polar vortex towards the end of November into December" as the current pattern fades and a new one sets up.

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Laura Ciasto, a meteorologist at the National Oceanic and Atmospheric Administration (NOAA), told Yahoo that the vortex has been "displaced for well over a week," though it hasn't yet reached the threshold for a sudden stratospheric warming, a rapid warming high in the atmosphere that can weaken or split the vortex.

"It's possible we are seeing that effect at the surface now," she said. "It's a classic chicken-or-the-egg situation."

What is a nor'easter?

A nor'easter is a storm situated along the East Coast of the U.S., with its namesake reflecting that the winds over the coastal area are usually from the northeast, the NWS says.

It forms when an area of lower air pressure draws in surrounding air and strengthens near the coast. It is often fueled by the clash of cold air from the north and warm, moist air over the Gulf Stream.

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While these storms can happen at any time of year, they are usually at their strongest between the colder months, from September through April.

Nor'easters "nearly always" bring precipitation in the form of heavy rain or snow, the NWS says, as well as winds of gale force, rough seas and, sometimes, coastal flooding. 

The most violent nor'easters have caused billions of dollars in damage. The storm is expected to be less severe than September's early-season nor'easter, which killed a New York City Housing Authority worker, flooded coastal communities and left more than 130,000 customers without power across the Northeast and mid-Atlantic, the Associated Press reported.

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