Millions under snow alerts as storm hits Western New York

Snow totals have reached 54 inches in Orchard Park, which is located about 15 miles south of downtown Buffalo, according to the latest snowfall reports out of the region from the National Weather Service. Three locations have met or exceeded 4 feet of snow:

The persistent snow band will continue to produce snowfall rates of 2 to 3 inches per hour through the evening. Later tonight the band will lift north into downtown Buffalo, bringing heavy snow. NWS forecasters in Buffalo are calling for an additional 20 inches of snow in the city between 7 p.m. Friday and 7 p.m. on Monday.

Two Erie County, New York, residents have died after suffering cardiac events related to shoveling and blowing snow, county executive Mark Poloncarz announced.

“We send our deepest sympathies and remind all that this snow is very heavy and dangerous,” Poloncarz said in a tweet.

He also reiterated the importance of staying off the roads and thanked residents for their diligence.

“The vast majority of Erie County residents have done the right thing and stayed off the roads. Thank you!” Poloncarz tweeted. “Unfortunately, it only takes one or two vehicles to tie up plow and first responder crews. Please stay home.”

Vehicles "who should not be driving" are getting stuck on roads, and even snow plows are are getting stuck "in the worst parts of the storm," Poloncarz said in another tweet.

The travel ban in the northern and southern parts of the county have been lifted, Poloncarz said, and they don’t anticipate reinstating those bans at this time.

Snowfall totals south of Buffalo have now reached 4 feet in at least one location. Blasdell, New York, about 8 miles south of Buffalo, has received 48 inches of snow, including 6 inches in a single hour, between 1 p.m. and 2 p.m. Heavy snow will continue falling the remainder of the day and through the night.

Here are a few other top totals as of early Friday afternoon, according to the National Weather Service:

Well, it'd be hard to try to play football in this much snow.

The Buffalo Bills posted photos of the team's Highmark Stadium covered in snow on Friday. The NFL has already moved Sunday’s Bills game against the Cleveland Browns to Detroit.

The stadium is in Orchard Park, New York, which is estimated to have gotten a whopping 3 feet of snow so far.

Areas south of Buffalo have observed 3 feet of snow so far, according to the National Weather Service.

View the most-affected places here:

Thundersnow is exactly what the name suggests – a snowy thunderstorm. But the winter version of a thunderstorm is far less frequent than the spring and summer thunderstorms most people are used to.

That is because the creation of thunder and lightning require significant amounts of atmospheric instability, which requires warm air. This is ample in the spring and summer, but not as much during winter snow storms.

Thundersnow is a rare phenomenon seen only in the strongest winter storms, such as nor’easters, intense blizzards and bomb cyclones.

On Thursday evening, this Twitter user heard the ever-elusive sound of thundersnow in Buffalo:

But the underlying mechanisms of thundersnow are the same as other thunderstorms. They require a combination of moisture above the Earth’s surface, instability in the air, and a lifting mechanism, according to the National Environmental Satellite Data and Information Service.

And where there is thunder, there is of course lightning – so while experiencing the wonder of thundersnow in person might be enticing, it can be dangerous. Staying inside your vehicle or a building is the safest way to avoid lightning strikes when you hear thunder.

Lightning associated with thundersnow storms is far less frequent than in summertime storms, however, and is generally the cloud-to-cloud variety, as opposed to strikes that travel to the ground.

And then there is the sound. Thundersnow doesn’t have the same “boom” you’d hear during regular thunderstorms. The heavy snowfall muffles the sound of the thunder, making it sound more like a low rumble than a loud, sharp bang.

Buffalo Mayor Byron Brown said the city has re-instituted a driving ban for South Buffalo as the area is now getting "hit extremely hard."

More than 20 inches of snow has fallen in South Buffalo, he told CNN's Kate Bolduan.

While Brown said the rest of the city is "in pretty good shape," he warned residents to stay home and not get on the roads, because the snow band is expected to move further north later tonight.

More than 100 pieces of snowplow equipment are out on the streets, he said.

"We're ready for what comes," he said.

According to a tweet from Erie County Executive Mark Poloncarz, "conditions have deteriorated very quickly.”

The New York State Thruway remains closed from Exits 53 through 59, which is located approximately from Buffalo to Dunkirk, New York, he said. 

Here's where the travel bans are located in Erie County:

CNN’s Kiely Westhoff and Laura Ly contributed reporting to this post.

Snowfall totals have now hit 3 feet in Orchard Park, New York, which is just south of Buffalo. 

“Two intense plumes of lake effect snow with snowfall rates of at least 3 inches per hour will continue northeast of [Lake Erie and Lake Ontario] through tonight,” the National Weather Service office in Buffalo said Friday morning. “Periodic thundersnow will remain possible near the lakes through tonight, as well as areas of blowing snow with winds gusting to 35 mph.”

Buffalo's airport reported heavy thundersnow in the last hour and visibility of only a quarter-mile.

Here is an updated preliminary list of the snowfall totals across parts of New York over the last 48 hours, according to the National Weather Service:

The Great Lakes is the only place where lake-effect snow occurs in the United States, except occasionally at the Great Salt Lake in Utah, according to CNN meteorologist Brandon Miller.

But what exactly is lake-effect snow?

Miller said it happens when very cold, windy conditions form over a not-so-cold lake. The lake might be 40 degrees, he said, and the air 0 degrees.

“That differential in temperatures creates some instability and the water provides a moisture source,” Miller said. “When it gets over land, it deposits water vapor as snow.”

Lake-effect snow generally doesn’t fall over the water because it needs the friction and topography of the land to bring out the snow.

Winds usually blow west to east in the Northern Hemisphere, so the lake-enhanced snow is pushed to the eastern side of the Great Lakes, Miller said.

Lake-effect snow can be very localized, especially when hills and mountains can cause these little weather systems to stall out and deposit a lot of precipitation in one spot.

According to the National Weather Service site on lake-effect snow, “wind direction is a key component in determining which areas will receive lake-effect snow. Heavy snow may be falling in one location, while the sun may be shining just a mile or two away in either direction.”

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