Tuesday: A 20 percent chance of snow. Cloudy, with a high near 32°F. Southwest wind between 9 and 17 mph, with gusts as high as 24 mph.

Tuesday Night: A 50 percent chance of snow, mainly after 11:00 pm. Cloudy, with a low around 23°F. Southwest wind between 15 and 17 mph, with gusts as high as 24 mph. New snow accumulation of less than one inch possible.

Wednesday: Snow likely, mainly after 11:00 am. Cloudy, with a high near 37°F. Breezy, with a southwest wind between 17 and 25 mph, with gusts as high as 36 mph. Chance of precipitation is 60%. New snow accumulation of 1 to 3 inches possible.

Thursday: Snow likely before 11:00 am, then rain and snow likely. Cloudy, with a high near 40°F. Breezy, with a west southwest wind between 17 and 21 mph, with gusts as high as 29 mph. Chance of precipitation is 70%.

Friday: A 20 percent chance of snow. Mostly cloudy, with a high near 38°F.

Saturday: A 20 percent chance of snow. Partly sunny, with a high near 33°F.

Sunday / New Year's Day: Partly sunny, with a high near 31°F.

Monday: Partly sunny, with a high near 30°F.

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Mountain Weather

Currently, under cloudy skies, mountain temperatures are in the teens Fahrenheit with westerly winds blowing 20-30 mph. A quick moving system will roll through this morning on a west to northwest flow. Winds will increase with gusts reaching the 40s and snow will fall, but it won't amount to much — only 1 to 2 inches in the mountains. Another shortwave disturbance is lined up to hit us again tomorrow. Wow, two storms in one week. Could this be La Nina knocking at our door?

Snowpack and Avalanche Discussion:

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

Our last snows were six days ago. Strong winds this weekend created impressive plumes of snow streaming off the high peaks and consequently loaded a few high elevation slopes while stripping others. The snowpack structure is weak with loose faceted snow at the ground. Some slopes are comprised almost entirely of facets, like Mount Ellis. Eric toured there on Christmas day and found over two feet of these loose grains. Slopes will quickly become unstable once they get burdened with new snow. Some slopes already have denser slabs on top of these facets and can avalanche by hitting a weak spot, or from large triggers like explosives at a ski area. Moonlight Basin Ski Patrol's video clip from Sunday's avalanche control illustrates this well.

Four of us skied into Beehive Basin yesterday to investigate the avalanche a skier triggered on Friday. It was low on the slope and small (two feet deep, 50 feet wide, 200 feet vertical, 35-38 degrees steep), but strained through a terrain trap of trees. Luckily no one was caught. As I stood at the crown and looked down slope I was reminded how a small avalanche could have big consequences. The slope was not an obvious avalanche path and the safe practice of skiing one at a time clearly was a good decision by the party. Sometimes we make mistakes and miss gauge stability. Only putting one person at a time on a slope along with carrying rescue gear is an insurance policy for when we are wrong.

The avalanche broke on facets at the ground. We dug many holes in the snow investigating the snow structure and performing stability tests. A few of our extended column tests broke easily and cleanly as seen in this video.

Since it is still possible to trigger similar avalanches throughout southwest Montana today, the Avalanche Danger is rated MODERATE on all slopes.

The Bridger Range:

The Bridger Range has weak snow, but good stability. Mark and Eric toured there on Saturday and found that most slopes are thinly covered and faceted, but lack a slab to make them unstable. New snow in the next two days could quickly bump up the avalanche danger. The best coverage, hence best skiing, will be found on slopes near the ridgelines that have deeper snow, likely from wind-loading.

All wind-loaded slopes will have a MODERATE Avalanche Danger today with a LOW Avalanche Danger rating everywhere else.

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.

Beacon Parks

The Friends of the Avalanche Center installed a Beacon Training Park outside West Yellowstone last Friday. It's located south of town on the main snowmobile trail. Stop by and do a quick practice before heading off into the mountains!

EDUCATION, EVENTS, PHOTOS, SNOWPITS, and VIDEOS

1. We've recently uploaded more photos and snowpits to our web site, more than what are linked in the advisory.

2. We're creating a series of "How To…" stability test videos. So far we've got clips on performing a CT and ECT. There are located under Stability Tests on the Resources page.

3. Check out all our education programs, Click Here.

Information provided by Doug Chabot, Mark Staples, and Eric Knoff from the Gallatin National Forest Avalanche Center. For Events and Education, or 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.