Today...Breezy. 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 15 to 20 mph. Chance of precipitation 20 percent.

Tonight...Breezy. Cloudy with a 50 percent chance of snow. Lows 19°F to 25°F. South winds 15 to 25 mph.

Monday...Breezy. Snow likely in the morning...then rain and snow in the afternoon. Snow accumulation of 1 to 2 inches. Highs 36°F to 42°F. Southwest winds 15 to 25 mph. Chance of precipitation 80 percent.

Monday Night...Breezy...cloudy. Snow likely in the evening...then chance of snow after midnight. Snow accumulation of 1 to 2 inches. Total snow accumulation 2 to 4 inches. Lows 16°F to 22°F. Southwest winds 15 to 20 mph. Chance of snow 60 percent.

Tuesday...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.

Tuesday Night...Breezy. Cloudy with a 50 percent chance of snow. Lows 22°F to 28°F.

Wednesday...Breezy. Snow showers likely in the morning...then snow showers and rain showers likely in the afternoon. Heavy snow accumulations. Highs 33°F to 39°F. Chance of precipitation 70 percent.

Wednesday Night...Colder. Cloudy with a 50 percent chance of snow showers. Lows 14°F to 20°F.

Thursday...Partly cloudy with a 20 percent chance of snow showers. Highs 29°F to 35°F.

Thursday Night...Partly cloudy with a 20 percent chance of snow showers. Lows 13°F to 19°F.

Friday...Partly cloudy. Slight chance of snow showers in the morning...then slight chance of rain showers and snow showers in the afternoon. Highs 33°F to 39°F. Chance of precipitation 20 percent.

Friday Night...Partly cloudy with a 20 percent chance of snow showers. Lows 15°F to 21°F.

Saturday...Partly cloudy with chance of snow showers in the morning...then mostly cloudy with chance of snow showers and rain showers in the afternoon. Highs 34°F to 40°F. Chance of precipitation 40 percent.

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

Mountain Weather

Over the past 12 hours a trace of new snow has fallen in most areas. Currently, winds are blowing out of the WSW at 5-20 mph and mountain temperatures are in the high teens to low 20's Fahrenheit. Today, plenty of sunshine will warm temperatures into the 30's Fahrenheit and winds will continue to blow out of the Westsouthwest at 10-20 mph. Clouds and wind will gradually increase by this evening as a storm pushes into the Pacific Northwest. A better chance of moisture will arrive tomorrow afternoon.

Snowpack and Avalanche Discussion:

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

Yesterday, my partner and I went for a tour up Bacon Rind in Yellowstone Park. Sunny skies and fresh snow were plentiful and before dropping in we put the shovels to the snow digging pits. As we dug down we did not expect to find anything unusual, i.e., unstable snow. However, a clean break nearly two feet down on my first compression test got me thinking. Only after our Extended Column Test (ECT) propagated cleanly across did I believe we may actually have a problematic layer. We did another ECT in the same pit and got the same results. We then changed aspect and dug another pit. Again, the ECT propagated on the same layer.

A thin layer of facets two feet below the surface is the layer of concern (pit profile). We found this layer on both east and west facing slopes around 8,800 feet indicating it was not isolated to one slope. This layer is similar to the one Doug and I found near Beaver Creek in the southern Madison range that resulted in a human triggered avalanche. The tricky thing about buried weak layers is they are often spatially variable - meaning they may or may not exist in a specific area. The best bet is to dig a pit or pits on the slope you plan to ride or on a slope with a similar aspect and elevation.

Although buried weak layers do not have a widespread distribution throughout our advisory, pockets of instability do exist. Slopes that have been heavily loaded by the wind will be the most likely to produce an avalanche. Avoiding large wind rolls or slopes under cornices will be the best way to avoid triggering a slide.

Before heading into avalanche terrain, evaluate the snowpack carefully and always think about the consequences of triggering a slide. Also, following simple rules such as putting one person on the slope at a time and watching your partner from a safe location will increase your safety margin when riding in the backcountry.

Today, human triggered avalanches are possible on wind loaded slopes where the Avalanche Danger is rated MODERATE. Slopes that have not received a wind load have a LOW Avalanche Danger.

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.