Today, the avalanche danger above 6000 feet is CONSIDERABLE on wind-loaded slopes and all slopes steeper than 35º. At mid-elevations the danger is MODERATE and lower elevations are rated at LOW danger. New snow accompanied by moderate winds Saturday night/Sunday morning formed fresh wind slabs on leeward and cross-loaded slopes. Dangerous avalanche conditions exist in steep and wind loaded terrain, cautious route-finding and conservative decision making are essential while traveling at upper elevations.
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Above 6500 ft.
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5000-6500 ft.
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3500-5000 ft.
Our entire advisory area benefitted from the recent storm. Up to 12 inches of new snow was accompanied by moderate winds with strong gusts. New snow, in addition to snow from Friday, could translate to 2-3 foot windslabs in the upper-elevations. The rain crust formed earlier in the week reaches into high elevations (above 7000 feet) and will provide an excellent sliding surface for new slabs. The storm slab that we faced yesterday is still a lingering concern today. Due to the thick layer of surface snow resting on the hard rain crust it may take longer than usual for this surface snow/crust interface to gain strength. It is important to carefully evaluate each slope you intend to ski or ride. Look for convex pillows of wind drifted snow on the lee sides of ridges and gullies. Pay attention to signs of instability like cracking, collapsing, "whumpfing", and, of course, recent avalanche activity.
Our data from alpine slopes across the advisory area are still limited, but we do continue to find weak snow in most of our field observations and until we can rule it out as a problem it will be included. This weak snow is found on top of and/or below the mid-November rain crust and the early December melt freeze crust (formed on sunny aspects). The December 9 rain event tested these weak layers in most, but not all, locations of our advisory area. Recent snowfall over the past few days continues to test the strength of these suspect layers.
The lowest elevation band (3500-5000 feet) has no to very little snow making travel and subsequent access to the upper elevations difficult in certain areas. However, as you approach the upper end of this elevation band and begin to encounter more snow, then treat those slopes as you would terrain in the mid- and upper elevation bands.
In Canyon Creek, on east - northeast aspects, an experienced backcountry skier reported initiating 2 soft slab avalanches sympathetically from the flatter terrain above the slide paths. He reported the snowpack in this location as sensitive. A separate party of skiers submitted photos of recent avalanche activity just outside the ski area boundary (photo).
Yesterday Todd and I rode into the Canyon Creek drainage in the southern Whitefish Range. On a north aspect we found approximately 2 feet of snow from our two recent storms sitting on top of the December 9 rain crust (photo, video). Our stability tests resulted in fracture and propagation at the crust/new snow interface with moderate force (ECTP 13).
On Sunday WMR ski patrol reported mixed results with explosive and ski cutting mitigation. Areas that did slide were relatively narrow pockets of either soft slab or cohesionless snow that slid on the Dec 9 rain crust.
Please let us know what you are seeing out there. Your observations are important and valued.
HOW TO SUBMIT OBSERVATIONS:
Email: [email protected]
Call and leave a message: 406.387.3821
You can also submit quick observations via text: 406.241.4571 (FAC mobile)
OR
Submit Snowpack Observations: http://www.flatheadavalanche.org/node/add/snowobs
Submit Avalanche Observations: http://www.flatheadavalanche.org/node/add/avyobs
Our most recent storm exited the area yesterday afternoon. Overnight, skies partially cleared with 4 a.m. temperature readings above 6000 feet between 17º-25º F with light winds out of the southwest. For today, expect partial clearing with a few bands of very light snow showers. Winds will shift to the northwest and remain light while temperatures will climb back to the high 20s to low 30s.
| 0600 temperature: | 13-26 deg. F. |
| Max. temperature in the last 24 hours: | 24-29 deg. F. |
| Average wind direction during the last 24 hours: | SW |
| Average wind speed during the last 24 hours: | 5-12 mph |
| Maximum wind gust in the last 24 hours: | 15-30 mph |
| New snowfall in the last 24 hours: | 0-4 inches |
| Total snow depth: | 30-50 inches |
| Monday | Monday Night | Tuesday | |
|---|---|---|---|
| Cloud Cover: | Mostly cloudy with light winds | Partly cloudy | Partly cloudy |
| Temperatures: | 24 - 33 deg. F. | 7-19 deg. F. | 22-30 deg. F. |
| Wind Direction: | NW | N | W |
| Wind Speed: | 5-7 | 3-5 | 5-9 with gusts to 20 |
| Snowfall: | 0-1 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.
