Rest Of Today...Breezy. Snow late in the morning...then snow likely in the afternoon. New snow accumulation around 2 inches. Total snow accumulation 4 to 6 inches. Highs 22°F to 28°F. Northwest winds 20 to 25 mph. Chance of snow near 100 percent.

Tonight...Breezy. Mostly cloudy. Chance of snow in the evening... Then slight chance of snow after midnight. Lows 5°F to 11°F. West winds 15 to 20 mph. Chance of snow 30 percent.

Sunday...Breezy. Mostly cloudy with a 50 percent chance of snow. Highs 21°F to 27°F. Southwest winds 15 to 20 mph.

Sunday Night...Breezy. Cloudy with a 50 percent chance of snow. Lows 9°F to 15°F. Southwest winds 15 to 20 mph in the evening.

Monday...Mostly cloudy in the morning then becoming partly cloudy. A 50 percent chance of snow. Highs 25°F to 31°F.

Monday Night...Mostly cloudy with a 40 percent chance of snow. Near steady temperature in the lower 20s Fahrenheit.

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

Tuesday Night...Colder. Mostly cloudy in the evening then becoming partly cloudy. A 20 percent chance of snow. Lows 8°F to 14°F.

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

Wednesday Night...Partly cloudy. Lows 7°F to 15°F.

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

Thursday Night...Partly cloudy with a 20 percent chance of snow. Lows 11°F to 17°F.

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

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Mountain Weather

A strong frontal passage moved through our area around 1:00 AM this morning producing strong winds and heavy snow. In a matter of hours, 4-5 inches of snow fell in the mountains around Big Sky and West Yellowstone while the Bridger Range and northern Gallatin Range picked up 2-3 inches. The mountains around Cooke City picked up 7-8 inches.

Winds spiked with the arrival of the front, producing gusts over 60 mph in Hyalite and Big Sky. Winds have mellowed a bit, but are still blowing out of the West North West at 20-30 mph with gusts in the 40s. Temperatures are ranging from 11 degrees in Cooke City to the high teens-low into the 20s Fahrenheit throughout the rest of our advisory area. Today, winds will remain strong out of the West North West and temperatures will rise into the 20s Fahrenheit. Snowfall will taper off this morning and skies will become partly cloudy by this afternoon. No significant accumulation is expected over the next 24 hours.

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 latest round of snow is one of a string of storms that has impacted our area over the past week. This onslaught of storm cycles has brought abundant snow and wind to Southwest Montana, producing numerous natural and human triggered avalanches from Cooke City to the Bridger Range. Nearly every slide over the past week has been due to a heavy wind load - a factor which has pushed many slopes past their breaking point.

Although we saw a quick reprieve from snowfall yesterday, we did not get a break from the winds. Yesterday, Mark and I skied in the northern Bridger Range and struggled to find any slope that had not been wind affected. We observed a natural wind slab avalanche near Ross Peak that occurred on a Northwest facing slope around 8,000 feet. This slide broke 1-2 feet deep and 50-75 feet across. A larger slide with a similar aspect naturally occurred on Saddle Peak Thursday morning. The mountains around Big Sky have also seen recent avalanche activity, with some slides stepping down to deeper layers.

We have been seeing similar activity on wind loaded slopes in the southern ranges as well. On Thursday, skiers in the Taylor Fork triggered a pocket of windblown snow and an observer in Cooke City reported several natural wind-slab avalanches. Many of these slides failed on deeper layers in the snowpack. Areas with weak faceted crystals near the ground do not have a specific pattern with respect to aspect or elevation, but are commonly found where the snowpack is relatively shallow. Experiencing cracking/collapsing and being able to shove a ski pole down to the ground are good indications the snowpack is shallow and potentially unstable.

With a fresh dose of snow and wind last night, human triggered avalanches remain likely on all wind loaded slopes where the Avalanche Danger is rated CONSIDERABLE. Slopes without a wind load 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.