Good morning. This is Eric Knoff with early season avalanche information bulletin issued on Wednesday, November 16 at 7:30 a.m. This bulletin is sponsored by Montana Import Group in partnership with the Friends of the Avalanche Center. Please remember that uphill traffic is not allowed at Big Sky or Moonlight Basin Ski areas. Uphill traffic is permitted at Bridger Bowl, but backcountry snow conditions do exist. This information will be updated as conditions change.
Over the past 48 hours intermittent weather disturbances have moved through southwest Montana producing heavy snow in some areas. The Shower Falls SNOTEL site in the northern Gallatin Range has recorded 1 inch of SWE totaling close to a foot of snow since Monday afternoon. The Bridger Range and mountains around Big Sky have picked up 4-6 inches over the past two days while the southern ranges received 1-2 inches. Currently, skies are clear and mountain temperatures are in the single digits above or below zero F. Winds are blowing 15-30 mph out of the WNW. Today a ridge of high pressure will build over the region producing clear skies and warmer temperatures. Highs today will climb into the mid 20s to low 30s F and winds will stay light to moderate out of the WNW. Conditions will begin to change tonight as another cold front approaches from the west.
The winter snowpack is building. Currently the Timber weather station at the Yellowstone Club and the Shower Falls SNOTEl site are recording the most snow in our forecast area with 29 inches of snow on the ground. Fisher Creek SNOTEL site outside of Cooke City is recording a total depth of 24 inches, while the mountains around West Yellowstone and the Bridger Ranger have between 10-15 inches on the ground. These depths vary with aspect and elevation, but the underlying message is clear - there is enough snow to produce avalanches.
Although snow amounts differ from one area to another, one element has remained constant - Wind. Over the past three days steady wind speeds of 30-40 mph have been recorded throughout our forecast area with gusts reaching 50-70 mph. The primary wind direction has been out of the WNW. The combination of fresh snow and strong winds has likely formed dense wind slabs on leeward slopes, some of which could be resting over weak faceted crystals developed during cold and dry weather earlier this season. Areas most prone to wind slab development are upper elevation slopes, particularly slopes located directly below ridgelines or off sub-ridges. Any slope that has received wind loading should be approached with caution. Complicating this scenario is the fact that slopes with the most snow often offer the best riding in early season but they also have the highest avalanche potential.
If you are heading into avalanche terrain, pay close attention to obvious clues such as recent avalanche activity or cracking and collapsing of the snowpack. These are clear signs the snowpack is unstable. Over the past week human triggered avalanches have been reported in the Bridger Range and mountains around Big Sky (photo1, photo2, video), and a natural avalanche was observed off Henderson Bench near Cooke City. Don't be fooled into thinking that shallow early season snowpacks are less hazardous. There has already been one avalanche related fatality in Utah. Now is the ideal time to check your avalanche rescue gear and practice with it thoroughly.
If you get out in the backcountry, please drop us a line at mtavalanche@gmail.com or call us at 587-6984. Any snowpack or avalanche information is especially valuable this time of year.
Wednesday, November 16, BIG SKY
Avalanche Awareness lecture at Grizzly Outfitters, 7 p.m.
Thursday, November 17, BOZEMAN
Avalanche Awareness lecture at Northern Lights Trading Company, 7 p.m.
Thursday, November 17, BILLINGS
Avalanche Awareness lecture at the Basecamp, 6:30 p.m.
Wednesday, November 30, BOZEMAN
Introduction to Avalanches with Field Course at MSU. Wednesday and Thursday evening lectures with a field course on Saturday. More info at http://www.mtavalanche.com/education/classes/workshops