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A snowpack seasonal disorder: forecasts in late March reflect both winter and spring-like conditions

As we near the end of March, spring-like weather is hitting certain areas of the west. But along with tailgate season comes a heightened risk of wet avalanches and concerns for melt-freeze layers that can lead to other dangers in the snowpack, such as slab avalanches.

Meanwhile, other areas are experiencing heavy, fresh snowfall and high winds, which have produced storm slab concerns.

Given the mixed bag of avalanche forecasts across the Western United States, here’s a closer look at a few regions to identify certain concerns for backcountry travelers.

Colorado

In the Rockies, much of the avalanche concern has to do with northeast to east facing slopes above treeline. Heavy winds in Colorado, along with fresh snow falling on a dust layer, created the opportunity for large slab formation. In a recent video, the Crested Butte Avalanche Center reported on this layer and its dangers after a group of backcountry skiers set off an avalanche on Schuylkill Ridge. On the fourth run of the day, a skier triggered a slab avalanche 100-feet wide and two-feet deep. The skier was carried by the avalanche but not buried.

Here is the video report of the avalanche.

Utah

In the Salt Lake region, similar conditions to those seen in Colorado and Montana are being reported by the Utah Avalanche Center (UAC). Wind slab is a concern above treeline, and while conditions in some of the regions under the UAC purview are currently rated Low at lower elevations, new snow may change that forecast.

The UAC speaks to how this new snow may affect snowpack over the course of the week.

“There is a great deal of uncertainty with this type of storm system, so I’ll hazard a guess of the danger rising to Moderate for storm snow instabilities on all aspects at the mid and upper elevations with new drifting in the high northerly terrain,” reports the UAC forecast as of March 28. “The danger may be more pronounced in the Logan and Ogden area mountains today.”

Montana

The Gallatin National Forest Avalanche Center reported on Monday, March 28 that a punch of new snow in the area has raised the avalanche danger rating to Considerable in areas above treeline. Again, this forecast is a result of windloading. All other slopes remain classified as Moderate.

“Large cornices have formed across the advisory area,” reports the Gallatin National Forest Avalanche Center. “These massive chunks of snow are now beginning to fail naturally and with human triggers.”

And with another six to eight inches of snow expected by Wednesday of this week, this danger rating is unlikely to decrease.

Pacific Northwest

As a storm hits the Mt. Baker and Paradise regions of Washington, the avalanche forecast is listed as Considerable due to a similar mix of winter and spring-like conditions. The Northwest Avalanche Center (NWAC) asks backcountry skiers to be on the lookout for loose wet slides, wind slabs and storm slabs—the latter, in particular, are affecting all areas and all slopes in certain regions under the purview of the NWAC.

“On Friday, the Baker pro-patrol reported natural slab activity above treeline on Mt. Shuskan but only small loose wet releases in the area and a generally right-side-up upper snowpack,” states the NWAC forecast on Sunday, March 27. “NWAC pro-observer Lee Lazzara was out near Mt Baker on Friday and generally found 50 cm of storm snow on a rain crust from March 21. He saw numerous loose wet avalanches on various aspects, and, despite warm temperatures, some ski-triggered loose dry avalanches were still seen on steep north slopes.”

This mix of winter and spring weather can create complex issues with snowpack, as observed over the past weekend and beginning of this week. When traveling in avalanche terrain, make sure to check with your local avalanche forecasters to stay current with hazards in the backcountry.

For a full report on U.S. avalanches, visit the Colorado Avalanche Information Center website and your regional avalanche forecasting service.

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