Good morning. This is Mark Staples with the Gallatin National Forest Avalanche Advisory issued on Thursday, March 3, at 7:30 a.m. Today’s advisory is dedicated in memory of Ben Richards. Ben died in an avalanche on Yellow Mountain four years ago. His mother, Becky, sponsors today’s advisory. This advisory does not apply to operating ski areas.
The mountains near Big Sky, West Yellowstone, and Cooke City received 1-2 inches of snow since yesterday. This morning temperatures were near 20F and winds were blowing 15-20 mph from the WSW. More snow should fall today. High temperatures will be near 30F and winds will continue unchanged. By tomorrow morning most areas will receive 3-5 inches.
The Bridger, Madison and Gallatin Ranges, the Lionhead area near West Yellowstone, the mountains around Cooke City and the Washburn Range:
The last significant snowfall was 10 days ago. Since then, snow has trickled into the advisory area with brief periods of clear weather but continued strong W and SW winds. This weather means 3 things:
- Without extended periods of clear weather, no prominent weak layers have formed. Some facets can be found near the snow surface, mostly on S aspects, but these are rare and/or not developed enough to be a concern.
- Light and sporadic snowfall has not stressed the snowpack
- Most slopes were either scoured or have stiff wind slabs on them, and the surface snow will develop a good bond with snow falling today.
Hard wind slabs are the main concern. Recent warm temperatures and a lack of stress from snowfall helped these wind slabs bond. Most will not produce human triggered avalanches but some could. The few slopes untouched by wind will have soft snow and a strong snowpack like I found on Mt Ellis (snowpits) yesterday in the N. Gallatin Range. A secondary concern - monster cornices exist on many ridgelines. They can break where and when you least expect. Watch for them when walking on ridges or parked in the fall line below them because falling cornices make great triggers for avalanches.
The snowpack is generally strong and deep and lacks reactive weak layers. One exception - very isolated slopes have facets near an ice crust about 2 ft deep. This layering produced a human triggered avalanche near Cooke City on Sunday (photo, snowpit). In Hyalite Canyon, a similar layering was found 2 weeks ago but has become unreactive in stability tests and not produced avalanches recently. For today, the avalanche danger is rated MODERATE on wind-loaded slopes that are steeper than 35 degrees. All other slopes have a LOW avalanche danger. A low danger ≠ no danger.
I will issue 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 587-6984.
PHOTOS, SNOWPITS, VIDEO and SURVEY RESULTS
1. We’ve recently uploaded more photos and snowpits to our web site.
2. We’re creating a series of “How To…” stability test videos. So far we’ve made 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.
UPCOMING EVENTS
SATURDAY: Pinhead Classic
The 30th Annual Pinhead Classic is on this Saturday, March 5th. “Gangsters and Flappers” is this year’s costume theme, so come dressed up to race, socialize and win great prizes. Registration is $30 and gets you course entry, t-shirt, pint glass, beverages, dinner, and dancing. All proceeds benefit the Friends of the Avalanche Center. Check out the website http://pinheadclassic.com for details.