Rest Of Today...Windy...snow. Areas of blowing snow. New snow accumulation of 1 to 4 inches. Highs 24°F to 30°F. Southwest winds 20 to 30 mph. Chance of snow near 100 percent.

Tonight...Windy...snow. Areas of blowing snow. Snow accumulation of 2 to 6 inches. Lows 16°F to 22°F. Southwest winds 25 to 30 mph with gusts to around 45 mph. Chance of snow near 100 percent.

Friday...Windy. Areas of blowing snow in the morning. Snow likely. Snow accumulation of 1 to 3 inches. Highs 25°F to 31°F. Southwest winds 20 to 30 mph decreasing to 15 to 20 mph in the afternoon. Chance of snow 70 percent.

Friday Night...Breezy. Snow likely in the evening...then snow after midnight. Areas of blowing snow after midnight. Snow accumulation of 2 to 4 inches. Lows 17°F to 23°F. Southwest winds 15 to 25 mph. Chance of snow near 100 percent.

Saturday...Breezy...snow. Snow accumulation of 3 to 5 inches. Total snow accumulation 10 to 26 inches. Highs 27°F to 33°F. Southwest winds 15 to 25 mph. Chance of snow near 100 percent.

Saturday Night...Cloudy with a 50 percent chance of snow. Lows 11°F to 17°F.

Sunday...Mostly cloudy with a 50 percent chance of snow. Highs 19°F to 25°F.

Sunday Night...Colder. Mostly cloudy with a 40 percent chance of snow. Lows 4°F to 10°F.

Monday...Mostly cloudy with a 40 percent chance of snow. Highs 22°F to 28°F.

Monday Night...Mostly cloudy in the evening then becoming partly cloudy. A 40 percent chance of snow. Lows 7°F to 13°F.

Tuesday...Mostly cloudy with a 30 percent chance of snow. Highs 20°F to 26°F.

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

Wednesday...Mostly cloudy with a 50 percent chance of snow. Highs 25°F to 31°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 Lionhead area near West Yellowstone and the mountains around Cooke City. Heavy snowfall, high winds and an extremely weak snowpack are causing unstable conditions. 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 run out zones should be avoided.

This warning will either be terminated or updated by 6:00 AM on January 20, 2012

Mountain Weather

Since yesterday morning the Lionhead area near West Yellowstone and the mountains near Cooke City received about 1 foot of new snow [1.0 inch of snow water equivalent (SWE)]. Other areas remained dry or received an inch of snow. All areas, however, received very strong westerly winds averaging 30-40 mph and gusting 60-80 mph. Temperatures have been rising over the last few days and were hovering near 20 degrees Fahrenheit this morning. Today temperatures will be in the low 20s Fahrenheit. Winds should ease a little and blow 20-40 mph from the West and Southwest. By tomorrow morning the mountains near Cooke City and West Yellowstone will receive another 12 inches of snow and the mountains near Big Sky will get 6 to 8 inches. Near Bozeman, 2 to 4 inches of snow will fall but more is definitely possible.

Snowpack and Avalanche Discussion:

The Lionhead area near West Yellowstone and the mountains around Cooke City:

In the last 24 hours the Lionhead area near West Yellowstone and the mountains near Cooke City received 1 inch of snow water equivalent (SWE) (about 1 foot of snow). We use this measurement of precipitation because it tells how much weight was added to the snowpack. More weight means more stress, and 1 inch of SWE puts a lot of stress on the snowpack. On Lionhead the snowpack is incredibly weak on all slopes. Under the stress of new snow, the snowpack will break and avalanche. Near Cooke City the snowpack is more variable and some slopes have relatively strong snow; however, many have very weak snow that will also avalanche. In these conditions avalanches can be triggered from relatively flat terrain underneath steeper slopes and avalanche run out zones should be avoided. Today both natural and human triggered avalanches area likely and the Avalanche Danger is HIGH.

The Bridger, Madison and Gallatin Ranges:

The Bridger, Madison and Gallatin Ranges did not receive the snowfall that fell further south. However, these areas received very strong winds that stripped snow from some slopes and formed hard wind slabs on others. Few slopes have been untouched by these winds. Yesterday on Mount Blackmore fresh wind slabs were my primary concern. In other areas these wind slabs are the primary concern but with an extremely weak snowpack, avalanches will break deeper in the snowpack or at the ground. Today the Avalanche Danger is CONSIDERABLE on wind loaded slopes steeper than 35 degrees. All other slopes have a MODERATE Avalanche Danger. Heads up: the avalanche danger could rise rapidly if heavy snowfall develops today, and avalanches could become likely even on non-wind loaded 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.

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.