It’s an annual tradition: Snow falls in Washington, a couple of inches cripple the region’s highways for hours, and smug Northerners scoff at D.C.’s seeming haplessness at the slightest touch of wintry weather.

“Tonight's 'snowstorm' has me more convinced than ever that Washington , DC wouldn't survive 10 minutes in a zombie attack,” Jeffrey Goldberg of the Atlantic snarked on Twitter on Wednesday night, after a light dusting of snow turned roads in the District, Northern Virginia and Maryland into icy toboggan runs jammed with stalled and crashed cars.


“All terrorists really need to do to cripple Washington, DC is steal a snow maker from a ski resort,” a Philadelphia talk-show host named Rich Zeoli tweeted Thursday.

But despite all the jibes about This Town, the repeated dysfunctions of the region’s snow-preparation efforts are no joke for the motorists who were caught in hours of delays and dozens of car accidents Wednesday night and early Thursday — especially as a much more powerful winter storm prepares to roll in and shut down Metro’s rail system for the weekend. The outrage over local governments’ failures to put enough salt on the roads before Wednesday’s snowfall prompted D.C. Mayor Muriel Bowser to apologize Thursday, while the government of Arlington, Va., sought to shift much of the blame by providing a list of highways that the state is responsible for maintaining.

This all raises a question: Why does snow so frequently yield paralysis in the capital of the world's most powerful nation ? Why was even President Barack Obama’s SUV stuck crawling through Wednesday’s snowbound traffic?

The answer includes a combination of sprawling development, the Beltway region’s fractured government and some cold-hard science.

“It’s a pretty unusual combination of factors,” said David Snyder, former mayor of Falls Church, Va. Snyder is the incoming chairman of the National Capital Region Emergency Preparedness Council, and he says the answer is a lot more nuanced than most people realize.

One factor is the climate — a border zone that occasionally experiences frigid winter days rivaling New England, but often skews toward the more temperate South — which prompts a constant will-it-or-won’t-it guessing game about snowfall forecasts that are more straightforward in colder metropolitan areas. (That’s why predicted snowstorms so often turn out to be rain, sleet or the dreaded “frozen mix.”) Another is the region’s rapid growth, which hasn’t been accompanied by matching improvements by the region’s District, state, county and city governments to their roads, rails and bus systems.

And then, he said, there are the people themselves — and not just know-nothing transplants from warmer climates who can’t handle winter-weather driving. Snyder put some of the fault for Wednesday’s havoc on D.C. motorists who may have seen early reports that roads were clogged but refused to stay in place until the traffic cleared up.

“To say the least, we're a region filled with very intelligent people who tend to respond to what their needs are, and not necessarily listen to public - safety messages when they’re put out,” Snyder said. “They tend to make up their own minds.

“We’re not happy with the results by a long shot,” Snyder added. “But I wouldn’t put that purely on the government. … The government is only one part of a very complicated mix.”

Then there’s the science behind the epic traffic jams, fender benders and highway: a mix of traffic engineering and materials science.

Cities with experience in fighting snow know the golden rule of salting roads: Use brine, and get it down before rush hour starts. Once cars are clogging the roads, there’s no way to ensure that there’s a seal of salt that prevents snow from immediately sticking to the pavement.

“The cities and areas that know how to do this well use brine very effectively,” said Lori Roman, of the Salt Institute. “It’s not expensive … and it’s a great tool in the toolbox when it comes to winter maintenance, so I have no idea why they didn’t do it.

“It seems to me that brine ahead of rush hour would have prevented a lot of yesterday’s problems,” Roman said.

Of course, that depends on a government agency deciding to lay down the brine. And for the D.C. region, that means a conglomeration of local, state and federal entities that share jurisdiction over the roadways. When they have ample time to coordinate — which may be the case with this weekend’s snowstorm — communication between the agencies can be effective, Snyder said. But when they have much less notice, as with Wednesday night’s flurries, the necessary coordination can suffer.

It’s a dynamic not dissimilar from why the federal government has had to step in to take on Metro’s safety problems: With two states, an independent municipality and a slew of government agencies tasked with executing overlapping responsibility, it’s unsurprising that problems arise.

“It’s a big deal when it’s not done right,” Roman said. “Politicians have lost their jobs because winter maintenance wasn’t done well.”

When Chicago Mayor Michael Bilandic lost his 1979 reelection bid, she said, “ Everyone knew it was because of poor winter maintenance, and citizens kept him accountable.” (It’s unclear how much then-D.C. Mayor Adrian Fenty’s fumbles in handling the February 2010 “snowmageddon” played in his reelection loss the following fall.)

More snow-hardy cities than Washington may scoff at the challenges presented by a mere one inch of snow. But that’s an incorrect assessment, said John Hourdos, associate professor of civil engineering at the University of Minnesota and director of the Minnesota Traffic Observatory.

Traffic was nearly at a stand-still on the outer loop of the I-495 Capital Beltway after snow fell Wednesday, Jan. 20, 2016, in National Harbor, Md. | AP Photo

He’s done significant research on the effects of weather on traffic patterns. One inch, he said, isn’t just a 'barely there ' amount of snow: Instead, it’s just enough precipitation to bring about the hydroplaning that drivers would more typically experience during a heavy downpour of rain.

“One inch of snow is like a very heavy downpour — it’s a lot of water,” Hourdos said.

Drivers can tell that their brakes aren’t responding as quickly as usual, so most motorists — especially those nervous about driving in the snow — leave themselves significantly more room to make sure they have space to slow to a stop in case they hydroplane. All that extra space takes an already clogged highway system and makes it virtually unusable.

“And all of a sudden, you reduce the capacity of your road by 50 percent,” Hourdos said. “You double your traffic — and in D.C., you already don’t have any room for wasting capacity on the roads.”

It’s different in places with drivers who encounter heavy snow daily.

“If there’s one inch of snow here [in Minnesota], nobody gives a damn,” Hourdos said. “They know how to use their vehicle. If it spins out of control or the brakes and the steering don’t work as well, instinctively you’re managing it — but that comes with years of exposure to these conditions.”

Of course, mockery and disbelief at the Beltway’s inability to cope with winter is such a venerable part of life in D.C. that even Obama engaged in it the week after he was sworn in.

“When it comes to the weather, folks in Washington don't seem to be able to handle things,” the president said wryly in January 2009, marveling that D.C. schools had shut down for icy rain that wouldn’t have canceled recess back in Illinois. He added, “We're going to have to try to apply some flinty Chicago toughness to this town.”

Just don’t expect the flinty tough Chicagoan to be braving the roads during this weekend’s snowy deluge.

“My guess is the president will stay warm and toasty here inside the White House,” press secretary Josh Earnest said Thursday.

Nolan D. McCaskill contributed to this report.