Today...Breezy. Mostly cloudy. Chance of snow in the morning...then slight chance of snow in the afternoon. Highs 25°F to 31°F. West winds 15 to 20 mph. Chance of snow 40 percent.

Tonight...Mostly cloudy. Lows 11°F to 17°F. Southwest winds around 15 mph in the evening.

Saturday...Cloudy. Chance of snow in the morning...then snow likely in the afternoon. Snow accumulation of 1 to 2 inches. Highs 31°F to 37°F. Chance of snow 70 percent.

Saturday Night...Cloudy with a 50 percent chance of snow. Lows 18°F to 24°F. Southwest winds around 15 mph.

Sunday...Mostly cloudy. Slight chance of snow in the morning...then slight chance of rain and snow in the afternoon. Highs 36°F to 42°F. Southwest winds around 15 mph. Chance of precipitation 20 percent.

Sunday Night...Partly cloudy. Slight chance of rain and snow in the evening...then slight chance of snow after midnight. Lows 19°F to 25°F. Chance of precipitation 20 percent.

Monday...Snow likely in the morning...then snow and rain likely in the afternoon. Light snow accumulations. Highs 35°F to 41°F. Chance of precipitation 60 percent.

Monday Night...Mostly cloudy with a 40 percent chance of snow. Lows 16°F to 22°F.

Tuesday...Mostly cloudy. Chance of snow in the morning...then chance of rain and snow in the afternoon. Highs 37°F to 43°F. Chance of precipitation 30 percent.

Tuesday Night...Breezy. Cloudy with a 40 percent chance of snow. Lows 19 to 25.

Wednesday...Breezy. Snow likely in the morning...then snow and rain likely in the afternoon. Highs 31°F to 37°F. Chance of precipitation 60 percent.

Wednesday Night...Cloudy with a 50 percent chance of snow. Lows 13°F to 19°F.

Thursday...Mostly cloudy with a 30 percent chance of snow. Highs 31°F to 37°F.

 Hazardous Weather  Gibbon Falls Forecast  Mammoth Forecast  Midway Forecast  Norris Forecast  Old Faithful Forecast 

Mountain Weather

Last night's powerful storm delivered more strong winds, snowfall, and some lightning. 7 inches of snow fell near Cooke City and West Yellowstone, 4 to 5 inches in the Gallatin and Madison Ranges, and 2 inches in the Bridger Range. Yesterday South and Southwest winds blew 30-40 mph with gust of 70-80 mph. As snowfall started around 9:00 pm, temperatures were near freezing and winds shifted to the West at similar speeds. This morning West winds were blowing 20-40 mph and temperatures had dropped into the teens Fahrenheit.

Today, temperatures will rise into the mid 20s Fahrenheit and West winds slowly decrease to 10-20 mph. Skies should have a mix of sun and clouds, and a trace of snow may fall in the southern half of the advisory area. More snowfall should come Saturday evening.

Snowpack and Avalanche Discussion:

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

The last 24 hours of weather will control today's avalanche issues which involve wind and new snow. This problem is easy to manage by watching for fresh deposits of wind-blown snow. Avoid these drifts and pillows, and you can mostly avoid avalanches. Yesterday, the Moonlight Basin Ski Patrol observed two small avalanches on wind loaded slopes, one natural and one skier triggered. More snow and wind overnight means similar slopes should see more avalanches today. With some lightning and hail reported last night, I suspect there may be some graupel under the new snow. These pellet-shaped snow particles can act as a temporary weak layer that should gain significant strength as early as this afternoon, but could be sensitive this morning.

The good news: On most slopes the snowpack is very strong and avalanches breaking in deeper layers of the snowpack are unlikely. Yesterday while riding near Lionhead, Doug and I felt very comfortable climbing and sidehilling across big slopes where we found a dense and supportable snowpack. Also, last night's storm started warm and finished cold, a "right-side up" storm.

Unfortunately 5 to 7 inches of new snow and strong winds mean human triggered avalanches are likely on steep, wind loaded slopes. Today the Avalanche Danger is CONSIDERABLE on wind loaded slopes great than 35 degrees and MODERATE Avalanche Danger on all other slopes.

The Bridger Range:

The Bridger Range experienced similar weather as other areas but only received 2 inches of new snow. With less snow – less avalanches. Today the Avalanche Danger is MODERATE on wind loaded slopes great than 35 degrees and LOW Avalanche Danger on all other slopes.

Heads up: Cornices have grown very large in recent weeks. These monster blocks of snow now severely overhang ridges. It's hard to know when or where they will break, but these tumbling blocks of dense snow are a hazard by themselves. Approach them with caution whether walking on a ridge or skiing or riding beneath them. Additionally, falling cornices make great triggers for avalanches.

PHOTOS, SNOWPITS, VIDEO and SURVEY RESULTS

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. The results from our survey are posted online. Thanks to all who participated. You can check out the results at http://bit.ly/fpLuSi.

In response to our survey we added a new page to the website with images of our snowpit profiles. This page is under the Resources/Other Info tab at http://fsavalanche.org/Encyclopedia/snowpit.htm

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.