Today...Breezy. Mostly sunny. Highs 32°F to 38°F. South winds 15 to 20 mph.

Tonight...Breezy. Partly cloudy in the evening then clearing. Lows 10°F to 16°F. Southwest winds 15 to 20 mph.

Tuesday...Mostly sunny in the morning then becoming partly cloudy. Highs 27°F to 33°F. Southwest winds around 15 mph in the late morning and afternoon.

Tuesday Night...Mostly clear in the evening then becoming partly cloudy. Lows 12°F to 18°F. Southwest winds around 15 mph in the evening.

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

Wednesday Night...Mostly clear. Lows 14°F to 20°F.

Thursday...Breezy. Partly cloudy. A 20 percent chance of snow in the afternoon. Highs 30°F to 36°F.

Thursday Night...Breezy. 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 21°F to 27°F.

Friday Night...Colder. Partly cloudy with a 20 percent chance of snow. Lows 4°F to 10°F.

Saturday...Mostly cloudy with a 30 percent chance of snow. Highs 19°F to 25°F.

Saturday Night...Partly cloudy. Lows 2°F to 8°F.

Sunday...Partly cloudy with a 20 percent chance of snow. Highs 21°F to 27°F.

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

* AVALANCHE FATALITIES *

There were two avalanche fatalities outside Cooke City on Saturday. A snowmobiler triggered and was buried in a slide on Mt Henderson above Fisher Creek. The crown was 1 to 4 feet deep, 300-400 feet wide and ran a total of 1,200 vertical feet (photo, video). The rider was buried 2-3 feet deep and was recovered within 10-15 minutes. A skier south of Cooke City in Hayden Creek was also buried and killed in an avalanche. He triggered the slide near the bottom of the slope, but it broke well above him burying him at least 3 feet deep. Doug is investigating this avalanche today and we will have completed reports later in the week. Our condolences go out to both families.

Mountain Weather

A building ridge of high pressure will bring sunny and unseasonably warm conditions to southwest Montana today. Currently mountain temperatures are in the mid twenties to low thirties Fahrenheit with the exception of the mountains around West Yellowstone and Cooke City where temperatures are in the mid teens Fahrenheit. Winds are blowing 10-20 mph out of the West-southwest and will gradually increase to 15-30 mph by this afternoon. Clear skies and warmer temperatures are expected through tomorrow.

Snowpack and Avalanche Discussion:

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

On Saturday, avalanches claimed the lives of two individuals. This equals the total number of fatalities that the entire state of Montana experienced all of last season. Aside from the two separate avalanches that resulted in fatalities, numerous natural and human triggered avalanches were reported throughout southwest Montana over the holiday weekend.

This spike in avalanche activity is the direct result of a rapid and heavy load (1.5 - 4 inches of SWE) being deposited on top of a very weak snowpack. The layer of concern is the interface between the recent storm snow and the older, weaker facets near the ground. Any slope that has received additional loading due to wind is especially susceptible to avalanches.

I spent the past three days in Cooke City and was amazed by the sheer volume of avalanche activity. Natural and human triggered avalanches were widespread and many slides were triggered from either the bottom of the slope or from adjacent slopes, a clear sign of highly unstable conditions (video). Doug and Mark found similar conditions near Hebgen Lake on Saturday (photo). In addition, all the local ski patrols have experienced extensive avalanche activity during control work, most notably on wind-loaded slopes.

For today – the Avalanche Danger is rated HIGH on all wind loaded slopes where human triggered avalanches remain very likely. A CONSIDERABLE Avalanche Danger exists on non-wind loaded slopes. All avalanche terrain, including avalanche run-out zones, should be avoided.

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.

EVENTS, EDUCATION, 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.

3. Check out all our education programs, Click Here.

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