Traffic in New York City and its surroundings came to a standstill Thursday afternoon and evening as a blast of crippling snow swept through the region. The poorly predicted snowfall led to hundreds of traffic accidents, left some drivers stuck in their cars overnight and stranded children at school. Normally 30-minute commutes turned into 10-hour-long sagas.

The culprit was the same storm that delivered early-season snow to parts of the South, Midwest and Mid-Atlantic. Half a foot of snow came down in New York City, the most so early in the season on record. The 6.4 inches of snowfall recorded in Central Park turned into the second-snowiest November day on record in the city, dating to 1869.

This storm alone boosted the Big Apple to its fourth-snowiest November on record, a further testament to its rarity. It was also the biggest November snow event since the 1930s.

Despite growing signals of a major band of snow moving through the city later in the day, the National Weather Service had initially predicted hardly any snow.

The Weather Service forecast issued early Thursday morning called for little to no accumulation. Its afternoon prediction increased the amounts to several inches, but that was also an underestimate.

Reasons for the rapid forecast shift are numerous, but the primary one was the realization that a supersized snow band was about to plow into air that was colder than anticipated.

“[T]he ‘front-end thump’ of heavy snowfall is owed to something called frontogenesis,” wrote Capital Weather Gang’s Matthew Cappucci several hours before the snowfall began.It’s basically a tightening of horizontal temperature gradients in the atmosphere. When a big change of temperatures exists over a short distance, it can boost precipitation rates substantially.”

In this case, snow that began in New York City midafternoon quickly turned heavy heading toward sunset and beyond. Temperatures that had been above freezing dropped into the upper 20s in heavy snow, and eventually snow transitioned to a wintry mix in the evening. This cement-like wintry mix included denser sleet.

Questions of forecasts and lack of preparation aside, a primary cause of the commuting nightmare in and around the city was the timing and intensity of the snowfall. Those snowfall rates of one to two inches per hour are difficult for even well-prepared crews to keep up with. Even in situations with little to no traffic, streets would likely become impassable for a time under such conditions.

Turn the biggest city in the country loose under such a scenario, and it’s a perfect recipe for traffic mayhem

Similar rush-hour nightmares hit Washington in 2011 and 2016. The 2011 event, in particular, shared many similarities to Thursday’s commute in New York. In both cases, first flakes in the midafternoon spurred a mass exodus, filling roads with vehicles. Then pounding snow arrived, and gridlock engulfed the area.

Major snow-induced commuting disasters have hit U.S. urban centers in recent years — both north and south — all from a combination of bad weather and bad timing. Atlanta was hit in 2014. That same year another “commutageddon” spawned a million memes in Raleigh, N.C.

Even Chicago isn’t immune to the perils of terribly-timed snowflakes, where a storm snarled traffic in February 2011.

While the storm was the source of many scary stories, it had a soft side, as well. There were plenty of beautiful scenes throughout the city, especially if you happened to be on foot.

As rumors swirl of a snowy winter ahead, it might be a good time to prepare for more wintry delays. Thursday’s storm may be only a sneak preview of what’s to come.