Feb 23, 2009 @ 12:00 am

February 23 Avalanche Advisory

Posted: 07:00
Good morning. This is Dudley Improta with the West Central Montana Avalanche Center’s avalanche advisory for February 23, 2009. This information is the responsibility of the Forest Service and does not apply to operating ski areas. The avalanche danger rating expires at midnight tonight. But, the advisory can provide valuable information for evaluating avalanche hazard for the next 48 hours.
The advisory area includes the Bitterroot Mountains from Lost Trail to Lookout Pass, the Rattlesnake Mountains and the Southern Swan and Mission Mountains near Seeley Lake. For specific avalanche information about the St. Regis Basin visit the Idaho Panhandle National Forest Avalanche Center website.

Weather and Snowpack Analysis
Snotel sites in the region are showing significant settlement of the snowpack since Friday. Settlement of the snow generally indicates stability. The moderate danger we talked about Friday has diminished this weekend with warm temperatures and no precipitation. There has been some surface hoar formation that wasn’t destroyed by the sun on North aspects. Many folks we communicated with reported good skiing and riding conditions on Northerly aspects at elevations above 6000′, where the snow remained cold. No doubt we have developed yet another melt-freeze crust on Southeast/South/Southwest aspects from this weekend of balmy weather. So, we’ll be paying attention to surface hoar layers on the Northerly aspects and crusts on the Southerly aspects as possible future weak layers or sliding surfaces.

Current Avalanche Danger
As of Monday (2/23/09) morning the avalanche danger in the region is LOW. Natural and human triggered avalanches are unlikely. MOSTLY safe conditions exist. LOW avalanche danger does not mean NO avalanche danger. There are always isolated pockets of instability in the snowpack. These kinds of conditions would mainly be on high exposed ridges with wind deposits or on steep slopes with exposed rock outcrops.

Weather Forecast and Avalanche Outlook
It looks like (hopefully) some snow will head our way in the next couple of days. Snow will be widespread, but light, until Monday night and Tuesday. Still only moderate accumulations are expected (but we’ll take it). The chances for snow increase into Tuesday and Wednesday. If we get the new snow that is predicted expect the avalanche danger to go to MODERATE on slopes above 6000′ that are 35 degrees or steeper. Natural avalanches will be unlikely, human triggered avalanches will be possible.

If you have snow observations or any snow information you’d like to share please contact us at [email protected].

The next avalanche advisory will be issued on Friday, February 27, 2009.


This information is the sole responsibility of the Forest Service and does not apply to operating ski areas. The avalanche danger rating expires at midnight tonight but the information can help you make a more informed decision regarding travel in avalanche terrain for the next few days.

Our advisory area includes National Forest System lands in the Bitterroot Mountains from Lost Trail Pass north to Granite Pass, the Rattlesnake Mountains north of Missoula and the Southern Swan and Mission Mountains near Seeley Lake, MT. Avalanche information for the Lookout Pass/St. Regis Basin area is available from the Idaho Panhandle Avalanche Center.