Today...Breezy. Cloudy with a 40 percent chance of snow. Highs 16°F to 22°F. Southwest winds 15 to 20 mph.

Tonight...Breezy. Chance of snow in the evening...then snow likely after midnight. Snow accumulation up to 2 inches. Lows 8°F to 14°F. Southwest winds 15 to 20 mph. Chance of snow 60 percent.

Monday...Breezy. Cloudy with a 50 percent chance of snow. Highs 23°F to 29°F. Southwest winds 15 to 20 mph.

Monday Night...Cloudy. Snow likely in the evening...then chance of snow after midnight. Snow accumulation of 1 to 2 inches. Lows 6°F to 12°F. Southwest winds around 15 mph in the evening. Chance of snow 70 percent.

Tuesday...Breezy. Mostly cloudy with occasional flurries in the morning...then partly cloudy with slight chance of snow in the afternoon. Highs 20°F to 26°F. Southwest winds 15 to 20 mph in the afternoon. Chance of snow 20 percent.

Tuesday Night...Mostly cloudy. Slight chance of snow in the evening...then chance of snow after midnight. Lows 14°F to 20°F. Chance of snow 30 percent.

Wednesday...Cloudy with a 40 percent chance of snow. Highs 27°F to 33°F.

Wednesday Night...Cloudy with a 50 percent chance of snow. Lows 17°F to 23°F.

Thursday...Cloudy with a 50 percent chance of snow. Highs 28°F to 34°F.

Thursday Night...Cloudy with a 40 percent chance of snow. Lows 12°F to 18°F.

Friday...Cloudy with a 20 percent chance of snow in the morning... Then partly cloudy in the afternoon. Highs 21°F to 27°F.

Friday Night...Colder. Partly cloudy. A 20 percent chance of snow after midnight. Lows 2°F to 8°F.

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

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

♦ AVALANCHE WARNING ♦

The Gallatin National Forest Avalanche Center continues a Backcountry Avalanche Warning for the Sothern Madison Range and Lionhead area near West Yellowstone. Heavy snow and strong winds have loaded an extremely weak snowpack causing unstable conditions. Today, natural and human triggered avalanches are likely and the Avalanche Danger is HIGH on all slopes. Areas of unstable snow exist. Natural and human triggered avalanches are likely. Avalanche terrain including avalanche run out zones should be avoided.

Mountain Weather

Over the past 24 hours snowfall totals equal: 10 inches in the northern Madison Range, 8 inches in the Bridger Range, 4 to 6 inches in the southern mountains and 2 inches in the northern Gallatin Range. Winds decreased yesterday as the storm settled in; however, they picked back up this morning and are blowing 15-30 mph out of the West-northwest. Currently, mountain temperatures are ranging from 5°F to 15°F under clear skies. Today, skies will remain mostly clear and temperatures will warm into the high teens to low 20s Fahrenheit. Winds will stay out of the West at 15-30 mph. Clouds will build by this evening and winds will increase as another storm system approaches from the west.

Snowpack and Avalanche Discussion:

The Southern Madison Range and Lionhead area near West Yellowstone:

In the southern Madison Range and Lionhead area near West Yellowstone heavy snowfall and strong winds are pushing a very weak snowpack past its breaking point. A pervasive layer of weak facets at or near the ground are failing catastrophically under the weight of the new snow, producing widespread natural and human triggered avalanches.

Yesterday, skiers near Hebgen Lake remotely triggered numerous slides, a clear indication of highly unstable conditions. Other skiers and snowmobilers in the area also reported widespread instability. I expect hair trigger conditions will continue through today.

Due to the unstable nature of the snowpack it will be possible to trigger avalanches from a distance including the bottom of the slope. Avalanches also have the capability of propagating long distances and pulling back into lower angle terrain.

Today, the Avalanche Danger is rated HIGH on all slopes and travel in avalanche terrain is not recommended.

The mountains around Cooke City:

A more variable distribution of persistent weak layers in the mountains around Cooke City is making stability assessment a bit more difficult. Some slopes have a deeper and stronger snowpack which is supporting the most recent load, while other slopes have a variety of weak faceted layers which are failing and producing natural and human triggered avalanches.

Yesterday, Mark and his partner observed a large natural avalanche on the Southeast face of Scotch Bonnet, the result of a heavy wind Load. Mark also heard of a snowmobiler who was partially buried in a slide on the south end Henderson Bench.

The bottom line is Cooke City has received a significant amount of snow over the past five days, which is putting a tremendous amount of stress on the snowpack. While some slopes will stay put, many will avalanche under the weight of a skier or rider. Any slope that has received a wind load will be especially prone to avalanches.

Being conservative is the name of the game. Be extra cautious when traveling in avalanche terrain and always be thinking about the consequences of a slide.

Today, human triggered avalanches are very likely on wind loaded slopes which have a HIGH Avalanche Danger. Non wind loaded slopes have a CONSIDERABLE Avalanche Danger.

The northern Madison and Gallatin Ranges and the Bridger Range:

The Bridger Range and mountains around Big Sky received 8 to 10 inches of snow over the past 24 hours totaling close to 1 inch of SWE. The southern Gallatin Range received roughly half that amount. This rapid and heavy load is pushing a weak snowpack close to the tipping point. The additional weight of skier or rider will likely tip the scales on wind loaded slopes and slopes steeper than 35 degrees where human triggered avalanches are likely.

The northern Gallatin Range received less snow over the past 24 hours, but picked up enough to keep the avalanche hazard elevated. Wind loaded slopes are today's primary avalanche concern, but in areas like Mount Ellis and Little Bear which have a weaker snowpack, steeper slopes will also be prone to human triggered avalanches.

The Hyalite Drainage in the northern Gallatin Range deserves a special mention because it has more stable conditions. Recently formed wind slabs could produce and avalanche, but the overall likelihood of triggering a slide is less in this area.

Today, a stressed out snowpack will make human triggered avalanches likely on wind loaded slopes and slopes steeper than 35 degrees where the Avalanche Danger is rated CONSIDERABLE. Less steep, non wind loaded slopes have a MODERATE Avalanche 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.

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.