NASA/NOAA

From outer space down to the streets.

Updated January 23 at 1:41 p.m. EST

A massive snowstorm pummeled the Eastern Seaboard this weekend, shutting down major cities across the Eastern United States and dumping heavy snowfall from Kentucky to New York.

The historic blizzard swept northward along the mid-Atlantic coast on Friday evening, dropping between two and three feet of snow around Washington, D.C. and Philadelphia. New York Governor Andrew Cuomo imposed a travel ban in and around New York City as the storm nears, and the National Weather Service forecasts a potentially record-breaking 24 to 30 inches of snowfall for the city.

Eleven states and the District of Columbia have declared states of emergency as local, state, and federal officials urge residents to stay home and off the roads. More than 85 million people—or more than one in every four Americans—were covered by some kind of blizzard or winter-storm advisory on Friday, according to weather.com.

The storm has the makings of the “Big One” and so far appears “textbook,” according to the winter-weather expert who literally wrote the textbook on northeast snowstorms. As of Saturday afternoon, there were already eight storm-related deaths reported.

We’ll be tracking the snowstorm here throughout the weekend at various levels: meteorological, street, local, state, federal, airspace, and, thanks to satellites and space stations, planetary.

The Meteorological Level

In recent days, a low-pressure system originating in the eastern Pacific Ocean moved ashore and began tracking across the country. The storm will intensify as it picks up plenty of moisture from the Gulf of Mexico. Meanwhile, high pressure from Canada is expected build Friday and feed in the cold air to the system, producing snow.

Forecasters predict “prolonged, heavy snow” in at least 15 states and Washington, D.C.—which appears smack dab in the center of the snowstorm in radar images, and is expected to be the hardest hit—between Friday and Saturday. The snowfall is expected to come in two sustained rounds with wind gusts that may reach 40 miles per hour.

The Street Level

Road-treatment crews have been dispatched in cities along the East Coast. Expect driving conditions to worsen in the coming days.

Some snowfall Wednesday night resulted in slippery roads and dangerous driving conditions in some cities. In Washington, D.C., often teased for its acute inability to handle even the tiniest coat of snow, about 2 inches of the stuff turned commutes into hours-long ordeals as crews scrambled to salt roads. Witness:

The crowd-sourced road-conditions app Waze showed a map of the area peppered with symbols signifying traffic jams or fender-benders Thursday night. Even Washington’s most important resident wasn’t spared: It took President Obama’s motorcade about an hour and 14 minutes to trek the 15 miles between Andrews Air Force Base and the White House.

Authorities in Washington, D.C. shut down the city’s public-transit system on Friday afternoon and urged residents to remain off the roads. To the north, in Philadelphia, most public transit also shut down by early Saturday morning.

The Local Level

In most cities along the East Coast, mayors declared various emergencies that would allow them to tap into certain resources.

New York Governor Andrew Cuomo imposed a downstate travel ban starting at 2:30 p.m. Saturday, including New York City, where Mayor Bill de Blasio warned that motorists who remained on the road would be arrested. Local rail and buses will be suspended and above-ground New York City subway stations will be shut down Saturday afternoon.

De Blasio warned that the approaching storm is “one of the worst snowstorms in in New York City history.”

In D.C., Muriel Bowser on Thursday apologized to the city’s slow response to Wednesday night’s snowfall and declared a state of emergency in the district. On Friday, she urged D.C. residents to be in their homes by 3 p.m.

In Baltimore, Craig Moe declared a snow emergency, which allows city officials to designate certain streets as snow-emergency routes and prohibit parking in specific areas.

The State Level

Governors in Maryland, Virginia, North Carolina, Georgia, Tennessee, West Virginia, and Pennsylvania have declared states of emergency, which free up resources for storm response. The Delaware National Guard has also set up stations throughout the state.

The Federal Level

The Federal Emergency Management Agency, the Department of Homeland Security, and the National Guard are working with D.C. in its response to the storm.

The Airspace Level

Travelers should prepare for flight delays or cancellations. According to the flight-tracking site FlightAware, nearly 6,000 flights scheduled for Friday and Saturday have been canceled ahead of the winter storm. All flights at the three Washington and Baltimore area airports will be canceled Saturday.

The Planetary Level

Thanks to satellite imagery from the National Oceanic and Atmospheric Administration, we can get a good look at the snowstorm as it approaches. Here’s the latest image, released Thursday afternoon:

NASA/NOAA GOES Project

This post originally appeared on The Atlantic and will be updated as conditions change.

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