Caution advised for snow falling off of building roofs. Park accordingly.

Dangerous avalanche conditions may already exist in many back country areas, please call the Recorded Avalanche Advisory 406-587-6981 for the most current conditions. Also, see the Avalanche Advisory posted below.

Today: Mostly cloudy with a 50 percent chance of snow. West winds around 15 mph late in the afternoon. Highs 24°F to 30°F.

Tonight: Mostly cloudy with a 50 percent chance of snow. West winds around 15 mph early in the evening. Lows 12°F to 18°F.

Friday: Mostly cloudy with scattered snow showers. Chance of snow 40 percent. Highs 29°F to 35°F.

Friday Night: Partly cloudy. Lows 14°F to 20°F.

Saturday: Partly cloudy in the morning then clearing. Highs 35°F to 41°F.

Saturday Night: Partly cloudy in the evening...then mostly cloudy with a 30 percent chance of snow after midnight. Lows 19°F to 25°F.

Sunday: Breezy. Snow likely. Moderate snow accumulations. Chance of snow 70 percent. Highs 30°F to 36°F.

Sunday Night: Breezy...colder. Snow likely. Light snow accumulations. Chance of snow 60 percent. Lows 10°F to 16°F.

Monday: Mostly cloudy with a 30 percent chance of snow. Highs 20°F to 26°F.

Monday Night: Partly cloudy. Lows 7°F to 13°F.

Tuesday: Not as cold. Partly cloudy. Highs 28°F to 34°F.

Tuesday Night: Mostly clear in the evening then becoming partly cloudy. Lows 12°F to 18°F.

Wednesday: Partly cloudy with a 20 percent chance of snow. Highs 32°F to 38°F.

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Mountain Weather

This morning clouds were moving over the area with temperatures in the low teens Fahrenheit and winds averaging 10 to 15 mph from the West with gusts of 20 to 30 mph. A little snow may fall this morning followed by a better chance tonight. High temperatures will reach the low to mid 20s Fahrenheit and winds will continue from the West at 10 to 15 mph gusting to 25 mph. By tomorrow morning the mountains near Bozeman and Big Sky should get 2 to 3 inches of snow while areas further south will receive about an inch.

Snowpack and Avalanche Discussion:

Bridger, Gallatin, and Madison Ranges, Lionhead Area near West Yellowstone, and Cooke City:

The problem: Weak layers of faceted crystals exist in the upper three feet of the snowpack on many slopes (video). Some of these layers formed in mid-January and are easy to see while others formed more recently and are harder to see but will usually break cleanly in stability tests. This time of year very small, faceted crystals can form in a matter of hours and get buried. The Big Sky Ski Patrol ski cut a fresh wind slab 1 foot deep by 100 feet wide that fractured on a thin layer of facets that formed in the last few days.

Evidence of the problem: During the last 2 weeks these layers have produced human triggered avalanches. In Beehive Basin near Big Sky on Tuesday, I found one of these layers on a West facing slope. It was very obvious visually and while digging my snowpit but did not break in my stability test. I did not trust it and later learned the Big Sky Ski Patrol triggered an avalanche on a slope with a very similar snowpack structure. This stability test result is called "false stable". Read more in this article. Finding a soft layer of weak facets under a harder layer of cohesive snow is a red flag regardless of stability test results.

What to do: Stable slopes definitely exist but how to find one? It takes a little work. Dig several snowpits about 3 feet deep looking for these faceted layers. Conduct several stability tests. Do it all quickly. It's more important to dig multiple pits quickly than one that takes a while. A single red flag like a nearby avalanche, obvious weak facets under a slab, or poor stability test results is enough evidence to avoid avalanche terrain.

Triggering an avalanche remains possible especially if you hit a thin spot on a slope. These spots are often near rocks which may not be visible as was the case near Flathead Pass in the Bridger Range on Saturday (photo). For today the Avalanche Danger is rated MODERATE.

Minimizing False-Stable Test Results:

Already this season all three of us have gotten false-stable tests results, which are a bit scary. Stability tests are not 100% accurate and scores showing stability when things are unstable is dangerous, which happen about 10% of the time. This is why we dig multiple snowpits. Karl Birkeland and I studied this "false-stable" problem and made a presentation at the 2006 International Snow Science workshop which you can read HERE.

The next advisory tomorrow morning at 7:30 AM. If you have any snowpack or avalanche observations, drop us a line at mtavalanche@gmail.com or call us at: 406-587-6984.

EDUCATION, PHOTOS, SNOWPITS, and VIDEOS

1. For links to Articles, Education and (photos), (snowpits), or (videos) listed in the above report, please visit this Link.

2. They have recently uploaded more photos and snowpits to their web site, more than what are linked in the advisory above.

3. They have creating a series of "How To…" stability test videos. So far they have clips on performing a CT and ECT. They are located under Stability Tests on their Resources page.

Information provided by Doug Chabot, Mark Staples, and Eric Knoff from the Gallatin National Forest Avalanche Center. For Photos and Videos, please visit the Avalanche Centers Website!

If you have any snowpack or avalanche observations, drop them a line at mtavalanche@gmail.com or call: 406-587-6984.

For detailed Avalanche Terms utilized here, please see the Avalanche Glossary.