This has been a deadly winter for fun in the heavily snow-laden backcountry. Through early February, avalanches had killed 24 people in North America, including hikers, climbers, skiers and snowboarders.

Snowmobilers — including the five killed in late January in British Columbia — account for 12 of the 24 deaths. Every case is different, but a fatality in late January in Colorado is revealing. It was on a day of blue skies at Crested Butte in western Colorado, when six local men decided to hop on their snowmobiles.

Mindful of high avalanche danger, they opted for what seemed safer fun on the lower slopes of Ruby Bowl, about seven miles west of Crested Butte. After building a jump, they used the snowmobiles in yoyo fashion to ferry skiers and snowboarders up the slope for sliding and jumping.

Located just below tree line, at about 11,000 feet above sea level, the slope seemed tame. Every avalanche book on the planet warns of 30-to-45-degree slopes, and this one was just 20 degrees. Above their chosen playground, however, the slopes steepened to 32 to 42 degrees. That made all the difference.

In early afternoon, after eight laps, two of the men were riding uphill abreast on a snowmobile. Just as they turned the snowmobile, the avalanche from the steep slope above broke. It wasn’t a large avalanche, but it buried the snowmobile driver up to his shins. His unfortunate passenger, however, was washed downhill 340 feet into a small stand of trees, and directly into a tree well.

Others were quickly on the scene. They were equipped with transceivers, metal shovels and probes, the essential avalanche safety equipment. They picked up the signal of their companion and began digging. First one six-foot hole, then another. Nothing, but still the signal. Digging just a foot deeper, they found their companion.

All of this had taken a mere 15 minutes. It was still too long. The man died later in a hospital.

Avalanche transceivers, also called beacons, can save lives. But consider this: About 25 percent of all victims die of trauma, not suffocation. In that case, the beacon just helps searchers find the body more easily.

As demonstrated at Crested Butte, time is precious. “Your odds go down immediately with every ticking second, but you see a dramatic rate (of fatalities) after about 15 minutes,” says Brian Lazar of the Colorado Avalanche Information Center.

Colorado has an inland climate, usually featuring a few heavy storms followed by periods of cold. This creates weak, sugary layers of marble-like depth hoar, a recipe for slab avalanches. The January avalanche near Crested Butte had a fracture line that was three feet deep.

New technological wrinkles — air bags and Avalungs — have helped, but not that much. The best thing is to avoid an avalanche altogether. Colorado has led the United States in avalanche deaths since 1950, with 270 occurring from then through last year, followed by Alaska (145), Washington (116), Utah (114) and Montana (108). California comes in behind them with 66 fatalities, despite having just as many high mountains and far more people.

Colorado avalanche forecasters report that the 10 U.S. avalanche deaths in January within a nine-day span were typical in a surprising way: About 70 percent of fatal avalanche accidents occur within four days of a prior accident, according to a 2012 study. In other words, you can go weeks without an avalanche death — and then, wham-bam.

In British Columbia, where 80 percent of Canada’s avalanche fatalities occur, last weekend was a wham-bam. Seventeen snowmobilers were caught in a hellacious avalanche on Mount Renshaw, part of a snowmobiling paradise around the small town of McBride. Altogether, five men — all from Alberta, ranging in age from 42 to 55 — died. As at Crested Butte, other snowmobilers were quick on the scene with probes, beacons and shovels. As detailed by Canada’s Globe and Mail, they got to one of the victims within five minutes. It was still too late.

“Heartbreaking” was the reaction of Mary Clayton, communications director for the Canadian Avalanche Centre. “Clearly, we have a lot of work to do.”

Canadian avalanche professionals typically instruct about 8,000 people annually in safety. Just 10 to 15 percent are snowmobilers. The statistics argue that they need to pay closer attention. For the decade ending in 2014, avalanches killed 54 snowmobilers in Canada as compared to 49 skiers.

Meanwhile, the Canadian Avalanche Centre has shifted its instruction, says Clayton, with instructors now emphasizing terrain rather than the more complicated snow physics. Making safe route choices is a simpler story: Stay off slopes of more than 30 degrees — especially if there’s a steeper slope above.

Allen Best is a contributor to Writers on the Range, an opinion service of High Country News (hcn.org).