Recent dry weather has allowed our snowpack to gain strength, however our avalanche danger remains elevated. The avalanche danger is CONSIDERABLE on all aspects above 6000'. Triggering a storm slab or persistent slab avalanche remains POSSIBLE at all elevations. Persistent slab avalanches have the potential to be very large and destructive. Careful snowpack evaluation, cautious routefinding and conservative decision making are essential.
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Above 6500 ft.
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5000-6500 ft.
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3500-5000 ft.
Continued benign weather is allowing our recent storm snow to settle out and gain strength. The impressive natural storm slab avalanche cycle ended Saturday (see observation 1, observation 2) with this slab becoming more stubborn to trigger over time (see observation 1, observation 2). The storm slab is generally thicker in the Swan Range, where more snow fell, and in the Flathead Range/Glacier Park area where winds redistributed this snow. Today, a human triggered slide remains POSSIBLE, especially on steep unsupported slopes and convexities (rollovers). Obvious signs of instability are surface cracking under your feet or machine along with recent avalanche activity. Test the waters on small inconsequential terrain to get an understanding of the snowpack in your location before commiting to a larger slope.
A well documented weak snowpack structure exists in many locations of our advisory area. Last weeks storm stressed these underlying weak layers which resulted in avalanche activity on some slopes but no activity on others. This weak snow can be found buried under persistent slabs 3 to 6 feet thick (see observation) on slopes that have not slid. Today, a human triggered persistent slab is POSSIBLE with resulting avalanches large and dangerous. Collapses and whumphs are an obvious sign of instability (like this observation), but digging into the snow is the only way to know if this snow structure exists; reducing your exposure to avalanche terrain is the easiest and safest way to deal with this problem.
As the surface snow settles out traveling in the backcountry is finally becoming a bit easier allowing us to observe recent natural avalanche activity (see observation). Easier access, sunshine, beautiful fields of powder and a holiday can equate to a great day in the mountains. Start your New Year off on the right foot by easing into this terrain and acquiring intel on how the snowpack in your location is behaving. There is no better time than now to develop and implement a New Years resolution of traveling in avalanche terrain wisely.
The natural storm slab cycle has ended but these recently formed slabs remain POSSIBLE to be human triggered today at all elevations and on all aspects. Remain wary of steep unsupported slopes and convexities while this slab continues to strengthen. Since this is a surface snow problem it is ideal for hand pits and testing small inconsequential terrain throughout your tour.
Unfortunately, we continue to deal with our persistent slab problem where a poor snowpack structure with weak, faceted snow is now buried 3 to 6 feet deep. Some locations have a relatively strong snow structure (observation) but the only way to identify these slopes is to dig into the snowpack On Saturday, observers near Mt. Werner experienced widespread collapsing on this buried layer - a sure sign of a reactive snowpack. We believe the large magnitude slide which snapped numerous trees and reached the rail grade Saturday morning in John F. Stevens Canyon may have been a persistent slab avalanche. Choosing less consequential terrain is the easiest and safest way to manage this complex problem.
Recent moderate to strong winds easterly winds transported substantial snow in the eastern portion of our area. The BNSF snow safety team observed blizzard conditions with accompanying wind slab formation at valley floor locations Saturday. Shooting cracks, whumpfing and skier triggered wind slabs were noted. One large wind slab avalanche was noted on Elk Mountain in Glacier Park Sunday morning (see observation).
The Flathead Avalanche Center presents two engaging and free one-hour Avalanche Awareness talks this week. Join us at at Stumptown Snowboards in Whitefish on Wednesday, January 3, from 7 PM - 8 PM ro Stonefly Lounge in Coram on Thursday, January 4, from 7 PM - 8 PM. The class includes general information about avalanche hazard, how to avoid it, and proper equipment for traveling in avalanche terrain. . Contact [email protected] with any questions.
Arctic air retreated to the east side of the Continental Divide overnight with light west winds ushering in warmer temperatures at all elevations. High pressure will strengthen over our area resulting in valley temperature inversions and gradual warming in the higher terrain today and tomorrow. Dry conditions, light winds and partly to mostly sunny skies are anticipated until a weak disturbance moves in late Tuesday with minimal snow impacts through Thursday.
| Monday | Monday Night | Tuesday | |
|---|---|---|---|
| Cloud Cover: | Partly sunny with light winds. | Partly cloudy with light winds. | Mostly sunny and warming temperatures. |
| Temperatures: | 15 to 20 deg. F. | 4 to 9 deg. F. | 20 to 25 deg. F. |
| Wind Direction: | West | West | Southwest |
| Wind Speed: | 0 to 10 mph | 0 to 10 mph | 0 to 10 mph |
| Snowfall: | 0 in. | 0 in. | 0 in. |
| Snow Line: |
This advisory applies only to backcountry areas outside established ski area boundaries. This advisory describes general avalanche conditions and local variations always occur. This advisory expires at midnight on the posted day unless otherwise noted. The information in this advisory is provided by the USDA Forest Service who is solely responsible for its content.
