Early Season Avalanche Conditions Update for December 1, 2013
Hello! This is Steve Karkanen with updated early season avalanche safety information for Sunday, December 1, 2013.
This update is based on limited information and does not have a danger rating attached to it. We plan to begin issuing regular avalanche advisories starting December 15 and continuing every Tuesday and Friday through March.
The dry/clear weather of the past several days is now giving way to a strong cold front expected to bring several inches of snow, high winds and much colder temperatures to mountain locations during the next few days.
Mountain locations are receiving heavy snow this afternoon. Snowfall may increase in intensity (1-2 inches per hour) as the system gains strength from the west during the next 24-48 hours. Wind speeds will also increase, perhaps as much as 40-50 mph from the west. 16 to 24 inches of new snow is possible with this system.
On Tuesday, temperatures are expected to drop dramatically as a strong arctic front drops into western Montana. This front will bring strong northeast winds possibly up to 50 mph in the usual canyon locations.
During the clear weather, facets formed on or near the surface of the snowpack in many areas. Warmer temperatures, sun and wind likely destroyed much of this facet growth but there are existing pockets that are now getting buried.
Places to be mindful of this are shaded, open aspects that receive little or no direct sun at the higher elevations. The only way to be certain if a recently loaded slope has this weakness is to dig down and look for it.
The other avalanche concerns during this storm are wind slabs that form on leeward terrain and heavy new load on the old snow surface.
This welcome change back to winter comes with the need to heighten our awareness where ever the snow is deep enough to recreate on.
Pay attention to any sign of instability such as recent avalanche activity, cracking and collapse noises while traveling over the snow, look for recently wind loaded terrain and realize that most avalanche activity happens during and immediately after a snow storm.
If you get out, let us know what you see. You can easily send an observation (and photos) from our Submit Public Observation link. Your information is vital to our service and may help keep someone out of trouble.
The Missoula Office of the National Weather Service issues daily backcountry weather forecasts available here: Backcountry Weather Forecast.
We have several classes scheduled and are taking registrations for our popular Level 1 classes. These classes fill quickly so call soon. The contact information for each class is on our Education and Events page.
These classes meet the American Avalanche Association (AAA) education guidelines and are taught by professional members of AAA who have years of on the snow experience. Instructors are avalanche forecasters, professional ski patrollers, backcountry guides and EMT instructors. The proceeds from our courses help pay for avalanche advisories and education opportunities in western Montana.