Avalanche Advisory for December 19, 2008

West Central Montana Avalanche Advisory
Posted December 19th, 2008 at 0600

Good morning! This is Steve Karkanen at the West Central Montana Avalanche Center with the first regular avalanche advisory for the 2008-2009 season. This information is the sole responsibility of the Forest Service and does not apply to operating ski areas.

Weather and Snowpack Analysis

Observers at all locations in the Bitterroot and Rattlesnake Mountains report shallow unconsolidated snow cover on all aspects and elevations in the advisory area. Snow amounts range from 31” at Saddle Mountain near Lost Trail, 20” at Lolo Pass, 34” at Hoodoo and 40” at Stuart Peak. Temperatures early in the week were sub-zero and began moderating Thursday back up into the 20’s. Snow was just beginning to push into the area from the West. SNOTEL sites this morning have received 3-5” of new snow overnight. Cold temperatures have allowed faceted snow to grow at the ground and around the rain crust that formed 2 weeks ago and a thin surface hoar layer developed in some areas during the clear weather last week. These features may come into play later but are not currently a problem as they are not supporting a slab and the snow is not deep enough to cover ground anchors and brush.

Current Avalanche Danger

The avalanche danger is LOW on all aspects and elevations from 5000′ to 8000′. There may be isolated areas where dangerous avalanche conditions can be found on steep open terrain where ground anchors have been covered or where terrain has been wind loaded. These are typically at the higher elevations on the leeward side of ridges on North to East aspects.

Weather Forecast and Avalanche Outlook

This morning, the Missoula Office of the National Weather Service is forecasting a cold front to move through the area into Eastern Montana today. Steady snowfall will diminish this morning and transition into convective shower activity. Arctic air will spill over the continental divide later today and tonight bringing very cold wind chill temperatures into Sunday. On Sunday, a moist Pacific system moves into the Northern Rockies with potential for widespread snowfall.

Expect avalanche danger to increase this weekend as the mountains receive more snow and wind. Never expose more than 1 person at a time to a slope steep enough to slide, have a transceiver, probe pole and shovel on you and know how to use them. If you get out and see something you’d like to share with us, send us a note at [email protected] . Have a safe weekend!

We are dropping our coverage of the St. Regis Basin area near Lookout Pass. We felt it was unnecessary for 2 centers to cover this area, the terrain and elevation is more similar to areas the Panhandle Avalanche Center covers in their advisory and most users are from ID and WA locations. The Idaho Panhandle NF Avalanche Center will continue to issue avalanche advisories for the St. Regis Basin. Bookmark their website at:

Idaho Panhandle Avalanche Center

If you have any avalanche or snowpack information you’d like to share or have questions about the upcoming season, please contact us at [email protected] .

The next avalanche advisory will be posted December 22, 2008.