This is Mark Staples with early season avalanche information issued Saturday, November 23 at 7:30 a.m. Today’s information is sponsored by the Montana Fish, Wildlife, and Parks Recreation Trails Grant. This information will be updated as conditions change.
The last snowfall occurred Wednesday. Since then the weather has been clear, cold, and calm. This morning is no exception with winds blowing 5-10 mph and mountain temperatures in the low 20s F. Valley temperatures were in the single digits F in most places and below zero F in West Yellowstone. Clear sunny skies this morning will quickly bring temperatures into the 30s F and winds will remain light. A ridge of high pressure will keep dry weather in our forecast for the next week.
The strongest snow exists in the Bridger Range and mountains near Cooke City (photo). These areas generally do not have well developed faceted layers. Avalanche activity should be confined to the new snow layers. On Thursday in the northern Bridger Range, I triggered a sizeable slough about 6 inches deep on a steep rollover (video) and a skier triggered a few 6-8 inch soft slabs at Bridger Bowl, which is not open and is backcountry. A slide was reported in Frazier Basin in the northern Bridger Range and another at Lulu Pass near Cooke City, but we have little info on these slides. Today in these areas today, pay attention the upper foot of the snowpack and observe how it reacts under your skis or your track on small test slopes.
Weaker and more faceted snow has consistently been found in Beehive Basin near Big Sky (photo). Eric also found weak and faceted snow on Mt. Blackmore in the northern Gallatin Range (video). Even though these weak layers exist in the snowpack, it is not necessarily unstable because these weak layers do not have enough of a load on them for widespread instability. Places to trigger an avalanche, (aka places to avoid) would be areas with a wind slab or drift resting on one of these weak faceted layers. Look for this combo near ridgelines or rocky areas with wind drifted snow.
The upcoming week of dry weather will help current stability as the snowpack adjusts to the weight of snow that fell on Wednesday. Future stability could be a problem. Why? Warm sunny days and clear cold nights tend form weak faceted snow near the surface of the snowpack. If this process happens, it won’t be a problem until the next storm forms a slab of new snow on top of this potential weak layer.
DANGER RATINGS AND FIELD OBSERVATIONS
We will not be issuing danger ratings until we get more data about the snowpack. We need your help. Drop us a line with any of your snowpack observations, pictures or snowpits to mtavalanche@gmail.com. You can also call in your observations in at 587-6984.
EXTRA CREDIT READING
Some recent articles found on our Blog:
Avalanche Safety for Snowmobilers;
The Rules of the Game – safety and strategy in avalanche terrain;
Do phones interfere with avalanche beacons? ;
Staying on top during the Bozeman Ice Festival.
1-Hour Avalanche Awareness Classes
LEWISTOWN, Tonight, November 23, 3 p.m. at Eagles Club
WEST YELLOWSTONE, November 26, 6 p.m. at West Yellowstone Conference Hotel
BOZEMAN, December 2, 7 p.m. at Northern Lights Trading Company
Go to our EDUCATION CALENDAR for details and more courses.
Intro to Avalanches w/ Field Course, MSU; 4, 5 and 7 December
Info and registration: https://www.ticketriver.com/event/7112
Snowmobiler Intro to Avalanches w/ Field Course, West Yellowstone: 19 and 20 December
Info and registration: https://www.ticketriver.com/event/7116