Above 5000 feet, the avalanche danger is MODERATE and human triggered avalanches are possible. Fresh wind slabs continue to form in the alpine terrain. Older wind slabs have been slow to strengthen. Carefully evaluate wind loaded terrain before committing to a slope. Weak layers exist throughout our pack and remain a concern. Avoid steep, rocky terrain and slopes with a shallow snow pack.
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Above 6500 ft.
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5000-6500 ft.
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3500-5000 ft.
Over the past few days, in the true alpine terrain of our area, wind speeds have been sufficient to drift low density surface snow onto typical leeward aspects. Prior to this, atypical winds formed wind slabs on atypical slopes at upper elevations. These slabs have strengthened slowly due to the recent cold weather. An example of this was the small skier/rider triggered wind slab avalanche that Erich observed in the southern Whitefish Range on an atypical slope Friday (observation). Carefully assess wind loaded terrain before committing to it and keep in mind the potential for small avalanches to stress deeper weak layers resulting in deeper slides. Wind loaded slopes are easily identified by looking for smooth, rounded features on the surface.
Our snowpack consists of a variety of weak layers including depth hoar at the bottom of the pack, buried surface hoar and facets in the mid pack and recently formed surface hoar on the surface. In areas where a slab exists above these weak layers a human triggered avalanche is possible. Many of these locations have not slid this season because they have not received a sufficient load. Do not be that load that tips this balance. Look for these layers when you dig in the snow and avoid areas where you are more likely to trigger a deeper avalanche like steep, shallow, rocky areas.
We are deeply saddened to report that a skier sustained fatal injuries in an avalanche accident on Stanton Mountain in Glacier National Park Thursday, 01/05/2017. We extend our most sincere condolences to the family and friends. FAC staff, along with Glacier National Park Rangers, vistited the site on Friday. We will provide a complete report of their findings within a few days.
Saturday: Skiers on Sub Shields in southern Glacier Park observed surface hoar above 5000' in sheltered areas. They also noted wind loading on easterly aspects in the alpine.
Friday: Mark and Guy traveled to the Red Meadow area of the northern Whitefish Range. Once above the inversion (approximately 6000') they found widespread surface hoar on all aspects. At the snow surface, 8-10" of recent snow was found to be resting on decomposing surface hoar. The basal layer of the pack consisted of depth hoar. Erich was in the southern Whitefish Range were he noted a small skier/rider triggered wind slab avalanche that occurred during the day on a southerly aspect. Skiers in the Apgar Range in Glacier Park observed failures in the top 2 feet of new snow in their stability tests. They also noted a recent small slab avalanche.
Thursday: Skiers on Snowshed Mountain in the Flathead Range reported 2 natural wind slab avalanches at upper elevations.
Wednesday, BNSF Avalanche Safety reported recent avalanche activity in the John F Stevens Canyon in wind loaded terrain. Recent storm slab avalanche activity was reported in an area known as Dorothy's in the southern Whitefish Range. We were in the Cascade Creek drainage in the Flathead Range and found remnant crown lines from storm slabs that released earlier in the week. Wind was calm in this area and we could only see minimal drifting on surrounding peaks.Also on Wednesday, skiers were on Sub-Shields in the Lewis Range of Glacier National Park they found generally unconsolidated surface snow, atypical wind loading patterns, and evidence of recent cornice fall. They noted weak snow deep in the snow pack that was minimally reactive in stability tests.
See below for all observations this season.
Yesterday, high pressure remained parked over our area resulting in another day of strong valley inversions. Currently temperatures above 6000 range from 11-20º F , and winds are 5-18 mph gusting to 10-21 mph out of the southwest. Temperatures are expected to rise to the mid-twenties, and winds will remain out of the west - southwest at at 5-10 mph with gusts to 23 mph.
| 0600 temperature: | 11-20 deg. F. |
| Max. temperature in the last 24 hours: | 14-22 deg. F. |
| Average wind direction during the last 24 hours: | southwest |
| Average wind speed during the last 24 hours: | 2-14 mph |
| Maximum wind gust in the last 24 hours: | 16-27 mph |
| New snowfall in the last 24 hours: | 0 inches |
| Total snow depth: | 53-74 inches |
| Sunday | Sunday Night | Monday | |
|---|---|---|---|
| Cloud Cover: | Partly cloudy and continued warming. | Cold and clear. | Partly cloudy with seasonal temperatures. |
| Temperatures: | 18-27 deg. F. | -3 to 17 deg. F. | 19-27 deg. F. |
| Wind Direction: | West-southwest | Southwest | Southwest |
| Wind Speed: | 7-8 mph | 5-7 mph | 5-8 mph gusts to 28 |
| 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.
