Today...Breezy. Partly cloudy in the morning...then mostly cloudy with a 20 percent chance of snow in the afternoon. Highs 16°F to 22°F. Southwest winds 15 to 20 mph in the late morning and afternoon.

Tonight...Breezy. Chance of snow in the evening...then snow likely after midnight. Snow accumulation of 1 to 3 inches. Lows 10°F to 16°F. Southwest winds 15 to 25 mph. Chance of snow 70 percent.

Friday...Not as cold. Cloudy with a 50 percent chance of snow. Highs 25°F to 31°F. Southwest winds around 15 mph.

Friday Night...Snow. Snow accumulation of 2 to 5 inches. Lows 14°F to 20°F. Southwest winds around 15 mph. Chance of snow 90 percent.

Saturday...Snow likely. Snow accumulation of 2 to 3 inches. Total snow accumulation 4 to 8 inches. Highs 24°F to 30°F. West winds around 15 mph in the morning. Chance of snow 70 percent.

Saturday Night...Colder. Mostly cloudy in the evening then becoming partly cloudy. A 20 percent chance of snow. Lows 7°F to 13°F.

Sunday...Mostly cloudy. Slight chance of snow in the morning...then chance of snow in the afternoon. Highs 2°F1 to 27°F. Chance of snow 30 percent.

Sunday Night...Mostly cloudy with a 20 percent chance of snow. Lows 5°F to 11°F.

Monday...Mostly cloudy in the morning then becoming partly cloudy. A 20 percent chance of snow. Highs 23°F to 29°F.

Monday Night...Mostly cloudy in the evening then becoming partly cloudy. A 20 percent chance of snow. Lows 9°F to 15°F.

Tuesday...Partly cloudy with a 30 percent chance of snow. Highs 27°F to 33°F.

Tuesday Night...Mostly cloudy in the evening then becoming partly cloudy. A 30 percent chance of snow. Lows 10°F to 16°F.

Wednesday...Partly cloudy with a 20 percent chance of snow. Highs 26°F to 32°F.

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Mountain Weather

Winds increased yesterday and were blowing westerly 20-25 mph in most areas this morning except at the Bridger Ridge where they were blowing 40 mph. Clear skies overnight allowed temperatures to drop to near 0°F. Cloudy skies will return around noon today, and snowfall should start sometime this afternoon. High temperatures will be in the high teens to 20°F. Winds may subside a bit this morning but increase again this afternoon blowing 20-30 mph from the West and Southwest with gusts late this afternoon around 40 mph. Snowfall this afternoon and evening will favor the mountains near Bozeman and Big Sky where 3-6 inches should fall by tomorrow morning with other areas receiving 2-4 inches.

Snowpack and Avalanche Discussion:

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

This week most areas received over an inch of snow water equivalent (over 1 foot of snow) except the mountains near Cooke City which received about 2.5 inches of snow water equivalent. In simple terms, more snow = more avalanches, and there are two distinctly different avalanche concerns.

Generally the snowpack is strong and can support the weight of new snow, BUT the stress of this new snow has pushed areas with a weak snowpack to their breaking point. These areas are mostly places that have a snowpack less than 1 meter deep which has become weaker during the last month (Republic, Mineral, Big Sky). The Big Sky Ski Patrol triggered an avalanche with explosives on Tuesday that broke near the ground about 2-5 feet deep. Yesterday they triggered another in the Lenin slide path about 4 feet deep and 150 feet wide. Similar avalanches have been observed nearby on Cedar and Fan Mountains and near Cooke City. These areas are not widespread but deserve special attention. They do not have a specific pattern with respect to aspect or elevation and require a careful examination of specific terrain features. Likely areas are steep and rocky that may have been scoured during previous wind events.

Fresh wind slabs are a more widespread avalanche concern especially with strong winds and plentiful new snow to be transported to the lee sides of ridges and gullies. This morning the Bridger Bowl Ski Patrol noted obvious plumes of snow blowing in the moonlight both at ridgetops and mid-mountain. Yesterday an ice climber half way up a climb called the Dribbles in Hyalite Canyon triggered a slab of new snow resting on a sun crust. Fortunately he was not swept off the climb. He and his partner decided not to climb higher and descended. While this type of instability can heal quickly, it will remain a concern with more strong winds.

For today, wind loaded slopes will have a CONSIDERABLE Avalanche Danger. All other slopes will have a MODERATE Avalanche Danger.

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

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.