Rest Of Today...Breezy. Cloudy with a 50 percent chance of snow. Areas of blowing snow. Highs 14°F to 20°F. West winds 20 to 25 mph with gusts to around 40 mph.

Tonight / New Years Eve...Breezy. Partly cloudy. Slight chance of snow in the evening...then occasional flurries after midnight. Lows -4°F to 2°F. Southwest winds 15 to 25 mph in the evening. Chance of snow 20 percent.

Sunday - New Years Day...Not as cold. Partly cloudy. Highs 23°F to 29°F.

Sunday Night...Partly cloudy in the evening then clearing. Lows 5°F to 13°F.

Monday...Not as cold. Mostly sunny in the morning then becoming partly cloudy. Highs 32°F to 38°F.

Monday Night...Mostly clear in the evening then becoming partly cloudy. Lows 13°F to 19°F.

Tuesday...Mostly sunny in the morning then becoming partly cloudy. Highs 27°F to 33°F.

Tuesday Night...Partly cloudy. Lows 12°F to 18°F.

Wednesday...Partly cloudy. Highs 30°F to 36°F.

Wednesday Night...Partly cloudy in the evening then clearing. Lows 11°F to 17°F.

Thursday...Partly cloudy. Highs 30°F to 36°F.

Thursday Night...Partly cloudy with slight chance of snow in the evening...then mostly cloudy with chance of snow after midnight. Lows 7°F to 13°F. Chance of snow 40 percent.

Friday...Mostly cloudy with a 40 percent chance of snow. Highs 20°F to 26°F.

 Hazardous Weather  Gibbon Falls Forecast  Mammoth Forecast  Midway Forecast  Norris Forecast  Old Faithful Forecast 

AVALANCHE WARNING

The Gallatin National Forest Avalanche Center is issuing a Backcountry Avalanche Warning for the entire advisory area including the Bridger, Gallatin and Madison Ranges, the Lionhead area near West Yellowstone, the mountains around Cooke City. Heavy snowfall, high winds and an extremely weak snowpack are causing unstable conditions. Avalanches were occurring prior to last night's storm. More are expected. Today the Avalanche Danger is HIGH on all slopes. Areas of unstable snow exist. Natural and human triggered avalanches are likely. Avalanche terrain including avalanche runout zones should be avoided.

Mountain Weather

2011 goes out with a bang with snowfall measured in feet not inches. Since yesterday morning the mountains around Cooke City received 2 feet of snow. The mountains near West Yellowstone, the southern Madison Range, and the Bridger Range received 1 foot of new snow. Yes, that's right the Bridgers got snow! The mountains near Big Sky and Hyalite Canyon received 6-9 inches of new snow. Strong winds continued as well and were blowing 20-40 mph this morning. They were blowing from the Southwest yesterday afternoon and shifted to the Northwest this morning. Temperatures were in the low teens Fahrenheit.

Snowfall ended this morning, and today skies will slowly clear allowing some sunshine. Winds will blow 15-20 mph from the Westnorthwest with gusts 30-35 mph. Temperatures may drop a bit more into the single digits Fahrenheit.

Snowpack and Avalanche Discussion:

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

Avalanches were occurring yesterday prior to last night's snowfall which started wet and heavy. With nearly a foot of new snow in most areas and 2 feet near Cooke City, more avalanches will occur today. Snowfall amounts may vary with elevation as it was raining yesterday below 7000 feet, but the snowpack doesn't care whether it rained or snowed because it all adds weight. More weight means more stress. More stress on the snowpack means more avalanches. Precipitation totals (SWE) for the last 72 hours are:

• Cooke City – 4 inches of water (~ 4 feet of snow)
• West Yellowstone – 2 inches of water (~ 2 feet of snow)
• Taylor Fork – 1.9 inches of water (~ 19 inches of snow)
• Hyalite – 1.4 inches of water (~ 14 inches of snow)
• The Bridger Range – 1.5 inches of water (~ 15 inches of snow)
• Big Sky - 1.6 inches of water (~ 16 inches of snow)

Yesterday the Yellowstone Club Ski Patrol and the Big Sky Ski Patrol triggered large avalanches that broke near the ground. Some of these broke on slopes that had already avalanched weeks ago, and one broke as a patroller approached the slope before he deployed an explosive. These slides indicate that the snowpack was finally pushed to its breaking point.

Eric was near Lulu Pass outside Cooke City yesterday where he triggered a small slope and observed lots of collapsing and cracking. A skier near Miller ridge remotely triggered a small slide then observed a much larger natural avalanche nearby. Near West Yellowstone, a skier north of town remotely triggered a small avalanche and a snowmobiler south of town observed collapsing and cracking and a few natural avalanches.

In Hyalite Canyon, the snowpack has generally been stronger, and just before Christmas it was able to support the load of 15 inches of snow (about 1 inch of SWE) with few avalanches. Last night's snowfall and recent high winds will still mean you should be very cautious and I do expect some avalanche activity in that area. HOWEVER, many other places in the northern Gallatin Range like Mount Ellis have a very weak snowpack. Let's not forget about the Bridger Range. The snowpack is very, very weak and it received a rapid heavy load last night. There should be many avalanches in the Bridgers today.

For today, very dangerous avalanche conditions exists and travel in avalanche terrain or avalanche runout zones is not recommended. Natural avalanches are likely and human triggered avalanches are very likely and a HIGH Avalanche Danger exists on all slopes.

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.