Today...Windy. Snow in the morning...then snow and rain in the afternoon. Areas of blowing snow in the afternoon. Snow accumulation of 2 to 4 inches. Highs 29°F to 35°F. Southwest winds 15 to 25 mph with gusts to around 40 mph increasing to 25 to 30 mph with gusts to around 45 mph late in the afternoon. Chance of precipitation near 100 percent.

Tonight...Windy...snow. Areas of blowing snow. Snow accumulation of 4 to 6 inches. Lows 10°F to 16°F. Southwest winds 25 to 30 mph with gusts to around 50 mph becoming west 15 to 20 mph with gusts to around 35 mph early in the morning. Chance of snow 90 percent.

Saturday...Windy...colder...cloudy. Snow in the morning...then chance of snow in the afternoon. Areas of blowing snow in the afternoon. Snow accumulation of 1 to 2 inches. Total snow accumulation 7 to 14 inches. Highs 15°F to 21°F. West winds 15 to 25 mph with gusts to around 40 mph increasing to 25 to 30 mph with gusts to around 45 mph late in the afternoon. Chance of snow 90 percent.

Saturday Night / New Years Eve...Breezy...colder. Partly cloudy. A 20 percent chance of snow in the evening. Lows -7°F to 1°F. West winds 15 to 20 mph in the evening.

Sunday - New Years Day...Partly cloudy. Highs 21°F to 27°F.

Sunday Night...Mostly clear. Lows 3°F to 11°F.

Monday...Not as cold. Mostly sunny. Highs 32°F to 38°F.

Monday Night...Mostly clear. Lows 13°F to 19°F.

Tuesday...Partly cloudy. Highs 26°F to 32°F.

Tuesday Night...Partly cloudy. Lows 8°F to 14°F.

Wednesday...Partly cloudy. Highs 25°F to 31°F.

Thursday...Partly cloudy. Highs 27°F to 33°F.

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Mountain Weather

It snowed all day yesterday near Cooke City where an additional 12 inches of snow fell since yesterday morning. The Big Sky area and Hyalite Canyon received another 3-5 inches while further south near West Yellowstone and the Taylor Fork, the mountains received another 2-3 inches. The Bridger Range got a touch of rain yesterday and 1 inch of snow fell early this morning. Strong winds continued with gusts of 60-80 mph and steady 30-40 mph winds from the West and Southwest. This morning winds eased slightly and were blowing 25-40 mph from the Southwest. Temperatures were in the mid 20s Fahrenheit.

Snow was falling this morning at 4:00 a.m. and more will fall today and tonight. Guess which area will get the most snow? That's right, the mountains near Cooke City will get another 16-20 inches. Mountains near West Yellowstone will get 10-12 inches, and mountains near Big Sky and south of Bozeman will get 6-8 inches. In the Bridger Range there will be a tug-of-war between snowfall and downslope winds which tend to limit snowfall. It's hard to say who will win, but 2-4 inches should accumulate by tomorrow morning. Despite plentiful snow it may be hard to tell how much has fallen because winds will remain strong. Today they will blow steady at 15-20 mph gusting 40-60 mph from the Southwest. Temperatures will warm near 30 degrees Fahrenheit but a cold front moving over the area tonight will drop temperature into the single digits by tomorrow.

Snowpack and Avalanche Discussion:

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

The combination of new snow and very strong winds is always a good one to create avalanches. This combination is worse because most areas between Bozeman, Big Sky and West Yellowstone have a very weak snowpack. Yesterday I skied in the southern Madison Range near the Bacon Rind drainage. The weight of 5 inches of new snow pushed the snowpack just to its breaking point and we experienced subtle collapsing and cracking. Skiers near West Yellowstone experienced lots of collapsing and cracking, and snowmobilers near Cabin Creek observed several recent natural avalanches sliding on buried surface hoar. All areas have weak facets struggling to support the weight of new snow. Many but not all areas have an especially weak layer of buried surface hoar.

With new snow, strong winds and more snow falling, I expect more avalanches. Strong West and Southwest winds have loaded many slopes where natural avalanches should occur. Today, human triggered avalanches are very likely on these wind loaded slopes which have a HIGH Avalanche Danger. These slopes as well as flat terrain under these slopes should be avoided. Non wind loaded slopes have a CONSIDERABLE Avalanche Danger which means that human triggered avalanches are also likely.

The mountains around Cooke City:

The mountains near Cooke City are in a league of their own where snowfall can be measured in feet instead of inches. In the past 48 hours, nearly 2 feet of snow has fallen (2 inches of SWE). Even though the snowpack in this area is much stronger than the rest of the advisory area, this amount of snow will find any weakness in the snowpack and produce an avalanche. More snow will come today with strong winds, and avalanches will certainly break within the new snow. Other avalanches will break deeper in the snowpack on a few slopes. Today all wind loaded slopes have a HIGH Avalanche Danger. The few slopes not affected by the wind have a CONSIDERABLE Avalanche Danger.

The Bridger Range and northern Gallatin Range:

A touch of rain fell yesterday morning in the Bridger Range and parts of the northern Gallatin Range like Mount Ellis. Hyalite Canyon received 4 inches of snow. These areas have a lower avalanche danger than other parts of the advisory area because they received less snow. The snowpack in the Bridger Range and places like Mt Ellis in the northern Gallatin Range is just as weak as it is further south. Rain that fell yesterday only makes matters worse. Hyalite Canyon is the one exception where a relatively strong and deep snowpack exists.

Yesterday's weather was weird for late December in Southwest Montana. Weird weather can make weird avalanches, so don't let your guard down even though these areas did not receive much snow. Today the Avalanche Danger is rated MODERATE but could easily rise to CONSIDERABLE if more snow falls and strong winds continue.

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.

EVENTS, EDUCATION, 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.