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.

Today: Mostly sunny. Patchy freezing fog in the morning. Highs 21°F to 27°F.

Tonight: Mostly clear. Patchy freezing fog after midnight. Lows -2°F to 4°F.

Saturday: Sunny. Patchy freezing fog in the morning. Highs 21°F to 27°F.

Saturday Night: Clear in the evening then becoming partly cloudy. Patchy freezing fog after midnight. Lows 2°F to 8°F.

Sunday: Partly cloudy. Patchy freezing fog in the morning. South winds around 15 mph in the afternoon. Highs 25°F to 31°F.

Sunday Night: Mostly cloudy with a 20 percent chance of snow. Lows 7°F to 13°F.

Monday: Mostly cloudy in the morning then becoming partly cloudy. A 20 percent chance of snow. Highs 19°F to 25°F.

Monday Night: Partly cloudy with a 20 percent chance of snow. Lows 6°F to 12°F.

Tuesday: Partly cloudy with a 20 percent chance of snow. Highs 19°F to 25°F.

Tuesday Night: Partly cloudy with a 20 percent chance of snow. Lows 11°F to 17°F.

Wednesday: Mostly cloudy with a 20 percent chance of snow. Highs 22°F to 28°F.

Wednesday Night: Mostly cloudy with a 40 percent chance of snow. Lows 7°F to 13°F.

Thursday: Mostly cloudy with a 40 percent chance of snow. Highs 15°F to 21°F.

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Mountain Weather

With another temperature inversion in place this morning, mountain temperatures were in the high 20s Fahrenheit while valley temperatures were mostly in the single digits Fahrenheit except in West Yellowstone where they were -17 Fahrenheit. Winds were blowing 10 mph from the West and Southwest and gusting 15 to 20 mph. Today cold air moving into the area will compete with sunshine, and temperatures should remain in the high 20s Fahrenheit. Gusty winds, especially in the mountains near Bozeman, will blow 10 to 30 mph. A brief ridge of high pressure will come Saturday followed by a trough of low pressure that should bring some precipitation Sunday evening.

Snowpack and Avalanche Discussion:

The Bridger Range:

During the past three days strong winds have blown in the Bridger Range where a skier triggered and was caught in an avalanche yesterday. He and his partner went just north of Bridger Bowl to a chute called the Hourglass where they observed a freshly formed wind slab. The first skier in the chute triggered it on his third turn and was carried about 1000 vertical feet. Fortunately he was only partially buried and sustained cuts, scrapes, and bruises from small trees in the run out zone. See photo1, photo2, and a video of the avalanche.

During recent periods with cold clear nights and warm sunny days, the snow surface weakened and became faceted. More recently, strong winds formed wind slabs on these facets. This combination is the problem. It is tricky because wind slabs can be found on many slopes, but not all slopes have facets under these wind slabs. For today heightened avalanche conditions exist on wind loaded slopes steeper than 35 degrees where the Avalanche Danger is rated MODERATE. All other slopes have a LOW Avalanche Danger.

The Gallatin and Madison Ranges, the Lionhead area near West Yellowstone and Cooke City:

Yesterday, the Big Sky Ski Patrol observed a small, wet point release that triggered a thin wind slab resting on small, faceted crystals in their A-Z chutes. Also, two experienced avalanche professionals skied a North facing slope on Fan Mountain where observed a very small slide near rocks on a South facing ridge line. These slides indicate that some slopes have similar conditions to the Bridger Range. Fortunately the combination of wind slabs resting on small facets is not widespread. In Beehive, Middle, and Bear Basins just north of Big Sky yesterday, my partner and I found many slopes above treeline with a wind packed surface. We found weak, faceted crystals near the surface in places, but did not find the combination of wind slabs resting on these facets and felt comfortable skiing steep, exposed terrain.

Similar conditions exist near West Yellowstone and Cooke City. The two slides observed yesterday at Big Sky and on Fan Mountain are great clues from Mother Nature that unstable snow can be found on isolated terrain features but overall human triggered avalanches remain unlikely. For this reason today the Avalanche Danger is rated LOW. Remember - a low danger does not mean no danger.

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

PHOTOS, SNOWPITS, and VIDEOS

1. For links to Articles, Education and (photos) and (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.