Concerns in our snowpack remain with the variety of weak layers in our pack along with wind slabs that formed earlier in the week. The avalanche danger is MODERATE above 5000 feet. Human triggered avalanches are possible particularly on steep, wind loaded slopes and terrain with shallow snow where it is easier to affect deeper instabilities. Dig into the snow to look for these weak, faceted layers and carefully assess recently wind loaded terrain before committing to it.
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Above 6500 ft.
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5000-6500 ft.
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3500-5000 ft.
Earlier this week moderate to strong winds formed wind slabs on upper elevation slopes, particularly in the alpine. Decreasing wind speeds and warming temperatures over the past 2 days have helped to strengthen these slabs. However, all wind loaded terrain should be viewed with suspicion. Look for thick, smooth, and rounded pillows on the surface near ridgelines and terrain features that trap the wind drifted snow. Avoid steep, exposed slopes in the alpine that harbor these recent slabs. Also, keep in mind that even a small avalanche can trigger deeper instabilities resulting in a larger, more destructive slide.
Due to the combination of: low density snow, colder than normal temperatures and several intrusions of arctic air; our mid and basal snow pack contains a variety of weak layers. Recent warm weather has temporarily ended the continued weakening of these layers but the damage is done. Weak layers buried in the pack take a long time to strengthen and we will have to deal with these layers for some time. The only way to know if these layers exist beneath you is to dig into the snow and look for them. Where present avoid areas where you are more likely to trigger them like steep, rocky terrain.
Impressive amounts of surface hoar formed last weekend and early this week on all aspects at all elevations. Much of it was destroyed by sun, wind and rain, but in some locations it remains preserved beneath a thin layer of recent snow. It would be a good idea to pay attention to where this layer exists as it could become a problem in the future with additional snow and slab formation above.
Friday: Mark traveled to Rescue Creek in the Flathead Range where he saw evidence of a low elevation wet loose avalanche cycle that had occurred from the rain and warming event on Wednesday. We also noted a rain crust at all elevations and substantial brush that is still exposed at low and mid elevations. FAC staff (Guy, Adam and Zach) were in the Lost Johnny area of the Swan Range where they saw no evidence of recent avalanche activity. They did find buried surface hoar that was minimally reactive in their stability tests.
Tuesday: Seth was in the Flathead Range on Scalplock Mountain above Essex in GNP. where he observed no obvious signs of instability and little results in stability tests on NE and SE aspects. Poor structure to the snow pack with considerable depth hoar and other weak layers in the snow pack and widespread, sometimes very large surface hoar.
See below for all observations this season.
Yesterday, we enjoyed mild temperatures, periods of sun, and light winds. As of 5:00 a.m. temperatures above 6000 feet range from 16-26º F. Winds have changed direction and are currently out of the east-northeast at 2-7 mph with gusts from 4-13 mph. For today, expect partly cloudy skies with light snow showers entering our area this afternoon. Winds will continue with an easterly component at 0-5 mph. Light snow is expected tonight with mild temperatures.
| 0600 temperature: | 16-26 deg. F. |
| Max. temperature in the last 24 hours: | 29-35 deg. F. |
| Average wind direction during the last 24 hours: | southwest |
| Average wind speed during the last 24 hours: | 5-10 mph |
| Maximum wind gust in the last 24 hours: | 8-14 mph |
| New snowfall in the last 24 hours: | 0 inches |
| Total snow depth: | 52-69 inches |
| Saturday | Saturday Night | Sunday | |
|---|---|---|---|
| Cloud Cover: | Partly cloudy with snow showers in the afternoon. | Light snow showers. | Partly cloudy. |
| Temperatures: | 25-32 deg. F. | 12-21 deg. F. | 24-33 deg. F. |
| Wind Direction: | Southeast | South-Southwest | Southeast |
| Wind Speed: | 4 mph | 3-4 mph | 4-5 mph |
| Snowfall: | 0 in. | 0-1 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.
