Caution advised for snow falling off of building roofs. Park accordingly.

Dangerous avalanche conditions may already exist in many back country areas, please call the Recorded Avalanche Advisory 406-587-6981 for the most current conditions.

Today: Windy...snow. Areas of blowing snow. Snow accumulation of 5 to 9 inches. Southwest winds 20 to 30 mph with gusts to around 45 mph. Chance of snow near 100 percent. Highs 24°F to 30°F.

Tonight: Windy. Areas of blowing snow in the evening. Snow in the evening...then chance of snow after midnight. Snow accumulation of 1 to 3 inches. Total snow accumulation 6 to 15 inches. West winds 20 to 30 mph with gusts to around 45 mph decreasing to 15 to 20 mph with gusts to around 35 mph after midnight. Chance of snow near 100 percent. Lows 3°F to 9°F.

Tuesday: Breezy...colder. Mostly cloudy. Chance of snow in the morning...then slight chance of snow in the afternoon. West winds 15 to 20 mph. Chance of snow 30 percent. Highs 9°F to 15°F.

Tuesday Night: Colder. Mostly cloudy with a 30 percent chance of snow. Southwest winds around 15 mph in the evening. Lows -1°F to -7°F.

Wednesday: Mostly cloudy with a 30 percent chance of snow. Highs 6°F to 12°F. Lowest wind chill readings -11°F to -21°F in the morning.

Wednesday Night: Partly cloudy with a 20 percent chance of snow. Lows -2°F to 4°F. Wind chill readings -16°F below to -26°F.

Thursday: Breezy. Not as cold. Partly cloudy with a 20 percent chance of snow. Highs 17°F to 23°F.

Thursday Night: Partly cloudy with a 20 percent chance of snow. Lows 10°F to 16°F.

Friday: Mostly cloudy with a 40 percent chance of snow. Highs 21°F to 27°F.

Friday Night: Mostly cloudy in the evening then becoming partly cloudy. A 40 percent chance of snow. Lows 14°F to 20°F.

Saturday: Mostly cloudy in the morning then becoming partly cloudy. A 40 percent chance of snow. Highs 24°F to 30°F.

Saturday Night: Partly cloudy with a 30 percent chance of snow. Lows 14°F to 20°F.

Sunday: Breezy. Mostly cloudy with a 30 percent chance of snow. Highs 24°F to 30°F.

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Mountain Weather

Over the past 24 hours the mountains around Cooke City and West Yellowstone including the southern Madison Range picked up 4 to 5 inches of snow. The mountains around Bozeman and Big Sky picked up 1 to 2 inches. Today, an additional 3 to 4 inches will fall in the southern mountains including the northern Madison Range while the Bridger Range and Northern Gallatin Range will see 1 to 2 inches. Currently, temperatures are in the mid-teens to low twenties Fahrenheit and winds are blowing 20 to 30 mph out of the West-southwest with gusts over 50 mph in Hyalite and Big Sky. Today will be the warmest day of the week with highs reaching close to 30 degrees Fahrenheit. Winds will remain strong out of West-southwest blowing 20 to 30 mph with upper elevation gusts reaching 50 mph. Temperatures will drop this evening as conditions begin to clear and tomorrow will be a colder and drier day.

Snowpack and Avalanche Discussion:

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

Is the weather contributing to instability? Without leaving the office, I can tell you the answer is yes. This has been confirmed by recent avalanche activity in the mountains around Big Sky.

Yesterday, the Moonlight Basin Ski Patrol triggered a large slide during control work. The slide initiated within the new snow, but stepped down to weaker snow near the ground. The resulting debris field was 100 meters wide, 200 meters long and upwards of 15 feet deep. This event is a good reminder that our snowpack still harbors the potential for producing large and dangerous avalanches. The Big Sky Ski Patrol also triggered slides yesterday during control work. Here, nothing broke into older snow, but fresh wind slabs were still breaking 1 to 2 feet deep. Recent avalanche activity was also reported by snowmobilers on Buck Ridge south of Big Sky.

These reports indicate the snowpack is changing. The past 10 days of abundant snowfall, light winds and overall good stability has come to an end. Today, wind slabs will become more widespread as new snow and strong West-southwest winds continue to load leeward slopes. Areas below ridgelines or the lee side of cross loaded gullies will be likely places to find wind deposited snow. Wind drifts will increase in size, coverage and sensitivity today as the storm continues. Identifying and avoiding wind loaded slopes will best way to stay out of trouble.

On slopes that have not been wind loaded, stability is generally good. The lack of prolonged dry spells along with consistent snowfall has kept the formation of persistent weak layers to a minimum. On slopes that do have buried weak layers, triggering a slide will require finding just the right spot. Steep, upper elevation slopes, especially those with rocky margins and a shallow snowpack will be the most suspect. If you do decide to commit to steep terrain today, digging a snowpit on a representative slope to assess structure and stability is a wise idea.

Today, plenty of fresh snow and strong winds will make human triggered avalanches likely on wind loaded slopes which have a CONSIDERABLE Avalanche Danger. 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.

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.

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