The avalanche danger is LOW on all slopes due to decreasing wind speeds overnight coupled with no new snow. Remember LOW danger does not mean NO danger" Due to recent variable wind direction isolated pockets of wind slab exist, especially in the alpine terrain. There is still a possibility to trigger an avalanche in these areas. Carefully evaluate wind loaded terrain at all elevations and look for signs of instability like cracking and collapsing.
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Above 6500 ft.
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5000-6500 ft.
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3500-5000 ft.
Wind slabs can still be found in isolated pockets at all elevations and aspects. We have not received reports of wind slab avalanches nor have we found much evidence of wind slab formation in recent observations. However, these observations are limited and data from the true alpine country of our region is missing. Wind speeds over the past few days have been sufficient to drift snow with varying wind direction depositing this snow onto all aspects. It is still possible to trigger an avalanche in these pockets of wind slab. Evalutate all wind loaded terrain before commiting to a slope. Smooth rounded pillows, cracking and/or hollow sounding snow are all indicative of wind slabs.
In some locations across the advisory area we continue to find buried weak snow/crust combinations. These layers exist 1.5 to 2.5 feet from the snow surface. Recent stability tests illustrate the potential for these deeper weak layers to fracture and propagate across the slope. However, we haven't observed or received reports of avalanche activity on these layers in over 2 weeks. Yesterday, we found depth hoar in a shallow snowpack near the Continental Divide that propagated in our stability test (video). Regardless, continue to carefully assess each slope before committing to it. Areas that are particularly notorious for harboring these weak layers are typically steep and rocky with a shallow snowpack.
On Friday Guy traveled to the Skyland area in the Flathead Range, just west of Marias Pass. He found a thin snowpack with well developed depth hoar on southerly aspects and in stability tests this layer failed with propagation. On leeward aspects they found a soft surface wind slab that had bonded with the layer below.
Skiers in the Marion Lake area of the Flathead Range Thursday reported up to 3 to 4 inches of new, unconsolidated surface snow on protected aspects, and a layer of faceted snow about 18 inches from the surface that fractured and partially propagated across the column in stability tests at upper elevations. Skiers in the southern Whitefish Range found great skiing, but also layer of small facets about 2.5 feet from the surface that propagated across the column in stability tests.
We are waking up this morning to the lowest valley floor temperatures we have experienced this season. Naturally, John F. Stevens Canyon brings home the gold with a brutal -27º F. Over the past 24 hours, no new snow fell across the advisory area with northerly winds decreasing and shifting to the south-southwest around midnight. Currently, temperatures above 6000 feet range from -14º to -6º F, and winds are out of the south-southwest at 9-13 mph with gusts from 11-18 mph. Today, temperatures will struggle to to rise above 0º F at upper elevations. Light south-southwest winds are expected with tonight bringing another evening of bitterly cold temps. There is hope on the horizon with Sundays upper elevation temperatures possible reaching upper single digits/low teens.
| 0600 temperature: | -14 to -6 deg. F. |
| Max. temperature in the last 24 hours: | -9 to -1 deg. F. |
| Average wind direction during the last 24 hours: | Northeast |
| Average wind speed during the last 24 hours: | 5-13 mph |
| Maximum wind gust in the last 24 hours: | 17-22 mph |
| New snowfall in the last 24 hours: | 0 inches |
| Total snow depth: | 21-58 inches |
| Saturday | Saturday Night | Sunday | |
|---|---|---|---|
| Cloud Cover: | Partly cloudy and cold. | Colder. | Partly cloudy and cold. |
| Temperatures: | -8 to 5 deg. F. | -26 to -8 deg. F. | -2 to 7 deg. F. |
| Wind Direction: | North-Northeast | Variable (Northwest to Southwest) | West-Southwest |
| Wind Speed: | 10-20 mph with gusts to 35 mph. | 5-10 mph with gusts to 20 mph. | 5-10 mph with gusts to 25 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.
