A year ago, a snowstorm for the ages paralyzed the Washington and Baltimore regions. Dubbed “Snowzilla,” it unloaded 15 to 30 inches of snow across the area and would rank as one of the all-time greats.

Like most storms, the snow started peacefully Jan. 22, a Friday. The event would rage through the night and into the next day. Wind-swept snow, falling at a furious clip, drifted sideways and piled high.

For snow lovers, the storm salvaged an otherwise unremarkable winter.

El Niño sets the stage

An El Niño winter set the stage for this monumental storm.

El Niños have a history of sending moisture-loaded systems across the southern United States and toward the Mid-Atlantic. Many of Washingtonians’ snowiest winters have coincided with El Niños, including our snowiest winter on record, in 2009-2010.

A mega El Niño developed in the winter of 2015-2016, one of the strongest on record, earning the moniker Godzilla — a nickname that stuck.

While El Niños can be big snow producers, sometimes they draw so much mild Pacific air northward that the Mid-Atlantic sees more rain than snow. For this reason, many winter outlooks predicted less snow than normal.

But there was a recognition that if cold air was in place at the right time, Godzilla could deliver the moisture for a blockbuster snowstorm.

Models see the storm a week away

By the second week of January, the signals for a high-impact winter storm started to appear on weather models. The pattern featured the hallmarks of a significant snow event.

About five days ahead of the first flakes, weather models converged on the idea of a massive storm.

All the ingredients for a big snowstorm looked like they would come together. A moisture-infused low-pressure system would streak across the southwestern United States and then energize near the northern Gulf of Mexico. Next, the low-pressure system would move to a position near Cape Hatteras, N.C., and turn up the East Coast, drawing in loads of Atlantic moisture.

Importantly, high pressure would be poised to the north near the Canadian border, feeding cold air into the swirling mass of moisture. In every way, Snowzilla fit the mold of a monster D.C. snowstorm.

The event

The storm coincided with the coldest time of year. Temperatures were in the 20s so the flakes Friday afternoon and for the duration of the storm were fluffy, powdery and eager to drift. Friday night, as bands of heavy snow passed through the region, those drifts made travel treacherous or impossible.

A dry slot — a zone of very light snow — briefly passed over the immediate D.C. area Saturday morning, which prevented truly insane snowfall totals. But steady snow continued to sock western and northwestern suburbs — where some totals exceeded 30 inches.

Saturday afternoon, the storm’s comma head pivoted back across the entire region, and moderate to heavy snow resumed everywhere. Winds really started to crank up, gusting over 35 mph. Between 3 and 5 p.m., the conditions outside qualified as a “blizzard” in the D.C. area because of the high winds and visibility of 0.25 miles or less in snow and blowing snow.

As the sun began to set Saturday evening and the snow tapered off, truly massive untouched piles of snow lay on most objects.

It was an incredible sight, with scenes reminiscent of some of D.C.’s most extreme winter weather over the decades.

How it ranks

The storm ended up tied for fourth-snowiest on record in Washington, as measured at Reagan National Airport. The total of 17.8 inches is questionable, however, because of some observing irregularities that were documented.

Across the area, totals of 15 to 30 inches were common, with isolated higher totals in our far western and northwestern areas.

An amazing 29.2 inches of snow fell at Baltimore-Washington International Airport, making it the greatest snowstorm on record there back to the 1880s. Dulles International measured an equally impressive 29.3 inches, which came in just behind Snowmageddon’s 2010 total of 32.4 inches.

Although many of the D.C. area’s greatest snowstorms tend to focus their fury only on the Mid-Atlantic, extreme snowfall totals reached the New York City area, where JFK and LaGuardia airports reported their highest snowfall totals on record in a single storm.

Watch ‘Snowzilla' from the top of The Washington Post in this timelapse. (Ashleigh Joplin/The Washington Post)

In much of the D.C. region, Snowzilla accounted for about 80 percent of the annual snowfall. Before last winter, there was no instance of such a big storm causing such a large fraction of the winter snowfall. Although it was the winter’s only major event, it is one that will long be remembered.