Approach steep terrain with a critical eye. If your uncertainty is high, keep your slope angles low. You can still trigger persistent weak layers from shallow, rocky areas or convex slopes above about 6,000 feet. Signs of instability, like shooting cracks and collapses, may not always be clear. They vary from slope to slope and across the region. Simple, uniform terrain is the safest bet.
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Above 6500 ft.
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5000-6500 ft.
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3500-5000 ft.
Early season weak layers are buried between 2 and 4 feet deep under December snow. These layers are more developed and may be weaker nearer to the Divide and above about 6,000 feet. Avalanches that break under that strain, or the added stress of your weight, could be very dangerous. They can be triggered from convexities or from rocky areas where the snowpack is shallower. Approach alpine starting zones and steep avalanche paths with a healthy skepticism. Collapsing and deep shooting cracks, or recent natural avalanches should only confirm your careful terrain choices. Step out cautiously. When faced with uncertainty, stick to planar, well anchored, and lower-angled slopes.
There are several obvious changes in the forecast today. You’ll notice that as winds and temperatures have dropped, so has the hazard of Wind Slab and Loose Wet avalanche problems. Storm slabs have proved quick to heal as well. Those problems came and went with the last storm (19th-21st), the powerful winds on the 20th and 21st, and the almost-record temperatures that spiked yesterday. Reports of storm and wind instabilities and sluffing corresponded with those dates. Skiers and explosives triggered small and large slabs, and other slabs ran naturally during the storm. Rain to about 5,500 feet caused wet snow sluffing on the 21st. Other clues pointed to the obvious instabilities: lots of new snow and rain, strong winds, multiple nights without freezing...As forecasters, we love surface instabilities. You can trust ‘em.
What I don’t trust? The snowpack structure at upper elevations. That remains our wild card – our Wild Bill. The nice quiet neighbor with the bodies in the basement. He can take you by surprise. We were surprised when only a handful of persistent slab avalanches failed after the storm on Friday the 13th. We were surprised that a large avalanche failed in John F. Stevens Canyon during the last storm because that area had much less new snowfall than elsewhere in the region. It’s a shifty problem.
If you’re going to venture up onto slopes with good coverage, eye the snowpack with suspicion. The crusts and facets that are the source of our uncertainty are now buried 2 to 4 feet deep. More feedback from these layers has come from the Whitefish Range than the Swan Range, though we’ve only heard of 1 avalanche failing on the facet crust layers in the Whitefish Range. The real action has been concentrated further east where weak layers became more developed early in the season, and where winds have loaded alpine slopes with harder slabs. These graphics may help refresh your memory about where they problem is scariest.
As you brave the bush to find snow, especially nearer the Continental Divide, be skeptical about the stability of the slopes beneath your feet. Avoid trigger points like rocky, shallow areas and convex terrain that gets steeper at breakovers. Stick to planar, uniform slopes. Whumpfs and collapses or deep shooting cracks are reminders that weak layers are dangerous and can fail under your weight. The more uncertain you are, the more cautious you should be. It’s less likely that you’ll set old Wild Bill off, but if you do it probably won’t be pretty.
Today the weather is transitory with light snow showers and dropping temperatures as a cold front pushes past the region through Tuesday. Accumulations will be modest. Winds will be light. Wednesday and Thursday look dry.
| Monday | Monday Night | Tuesday | |
|---|---|---|---|
| Cloud Cover: | Mostly Cloudy | Mostly Cloudy | Mostly Cloudy |
| Temperatures: | 28 to 34 deg. F. | 19 to 23 deg. F. | 23 to 28 deg. F. |
| Wind Direction: | Southwest | Southwest | Southwest |
| Wind Speed: | 15G29 | 13G25 | 14G24 |
| Snowfall: | 0 to 1" in. | 0" in. | 0" in. |
| Snow Line: | 4000' | 2000' | 1500' |
This forecast applies only to backcountry areas outside established ski area boundaries. The forecast describes general avalanche conditions and local variations always occur. This forecast expires at midnight on the posted day unless otherwise noted. The information in this forecast is provided by the USDA Forest Service who is solely responsible for its content.
