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: Areas of blowing snow in the morning. Snow. Snow accumulation of 1 to 2 inches. Total snow accumulation 3 to 7 inches. North winds around 15 mph. Chance of snow near 100 percent. Highs 5°F to 11°F. Wind chill readings -10°F to -20°F.

Tonight: Mostly cloudy. Chance of snow in the evening. North winds around 15 mph in the evening. Chance of snow 40 percent. Lows -8°F to -18°F.

Saturday: Partly cloudy. Highs 2°F to 8°F. Lowest wind chill readings -18°F to -28°F in the morning.

Saturday Night: Partly cloudy. Lows -7°F to -15°F.

Sunday: Partly cloudy. Highs 3°F to 9°F. Lowest wind chill readings -16°F to -26°F in the morning.

Sunday Night: Partly cloudy. Lows -7°F to -13°F.

Monday: Mostly cloudy with a 20 percent chance of snow. Highs 4°F to 10°F. Lowest wind chill readings -22°F to -32°F in the morning.

Monday Night: Mostly cloudy with a 40 percent chance of snow. Lows -6°F to 2°F.

Tuesday: Not as cold. Mostly cloudy with a 20 percent chance of snow. Highs 15°F to 21°F.

Tuesday Night: Mostly cloudy in the evening then becoming partly cloudy. Lows 1°F to 9°F.

Wednesday: Partly cloudy. Highs 20°F to 26°F.

Wednesday Night: Partly cloudy. Lows 3°F to 11°F.

Thursday: Mostly sunny in the morning then becoming partly cloudy. Highs 20°F to 26°F.

 Hazardous Weather Forecast  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 Southern Madison and Southern Gallatin Ranges and the Lionhead area near West Yellowstone. About one foot of new snow rests on an extremely weak layer of faceted snow crystals. Today the Avalanche Danger is HIGH on all slopes. Areas of unstable snow exist. Natural and human triggered avalanches are very likely. Avalanche terrain including avalanche runout zones should be avoided.

This warning will either be terminated or updated by 6:00 AM on January 12, 2013

Mountain Weather

Since yesterday, the southern Madison Range and the mountains near West Yellowstone area received 8 to 10 inches of new snow. The Bridger Range and northern Gallatin Range received 4 to 5 inches while the mountains near Big Sky and Cooke City received a paltry 2 inches. Temperatures this morning were near 0 degrees Fahrenheit and northerly winds were fortunately only blowing 5 to 10 mph. Today northerly winds will increase to 10 to 15 mph and temperature should drop to about -10 degrees Fahrenheit. Snowfall will continue until this afternoon and produce an additional 2 to 3 inches in most areas. Very cold temperatures will last thru this weekend.

Snowpack and Avalanche Discussion:

Southern Gallatin and Southern Madison Ranges, and Lionhead area near West Yellowstone:

In the southern Madison and southern Gallatin Ranges and the Lionhead area near West Yellowstone, snowfall since Monday totals about 12 to 14 inches. This snow rests on an extremely weak layer of faceted snow crystals that formed during the first week of January. Prior to yesterday's storm, stability tests indicated that this weak layer could produce avalanches (video). With yesterday's additional snow, human triggered avalanches are now very likely. These avalanches may be triggered in flat terrain below steeper slopes. For today, dangerous avalanche conditions exist and the Avalanche Danger is rated HIGH.

Northern Madison Range, and Cooke City:

Since the beginning of the week, snow totals are 14 inches near Cooke City and 7 inches near Big Sky. While significantly more snow fell this week near Cooke City, this area mostly lacks a weak layer of faceted crystals under the new snow. There are exceptions especially in lower elevation areas like Town Hill. On Wednesday while riding near Cooke City, the main problem I found was an upside-down and heavily wind-affected snowpack. This means hard snow was resting on softer snow and required a full throttle to ride through fresh drifts. This combination is a good recipe for human triggered avalanches. Fortunately this unstable combination is typically short lived.

It's a different story near Big Sky which has a very weak layer of faceted crystals under the new snow (photo). On Monday along Buck Ridge, Doug and Eric found this weak layer to be so fragile that it could barely support its own weight much less the weight of any new snow. For today, the Avalanche Danger is CONSIDERABLE on slopes steeper than 35 degrees. Less steep slopes have a MODERATE Avalanche Danger.

Bridger Range, and Northern Gallatin Range:

The mountains near Bozeman received 4 to 5 inches of low density snow overnight. This light snow combined with only an inch or two early this week will not increase the avalanche danger much today. These areas have a weak layer of facets that formed during the first week of January (video) but last night's light snow did not add much stress to this layer. Additionally, strong winds this week made the distribution this weak layer somewhat random, and it does not exist on every slope. For these reasons, today human triggered avalanches are possible and the Avalanche Danger is rated MODERATE.

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.

EDUCATION, PHOTOS, SNOWPITS, and VIDEOS

1. For links to Articles, Education and (photos) and (videos) listed in the above report, please visit this Link.

2. They have recently uploaded more photos and snowpits to their web site, more than what are linked in the advisory above.

3. They have creating a series of "How To…" stability test videos. So far they have clips on performing a CT and ECT. They are located under Stability Tests on their 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.