January 5th, 2009 Avalanche Advisory

Posted Monday January 5th, 2009 at 0630.

This is Steve Karkanen at the West Central Montana Avalanche Center with the avalanche advisory for January 5th, 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 you can expect avalanche conditions to remain similar unless weather conditions change significantly.

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.

Weather and Snowpack Analysis

Our weekend weather gave us a respite from the seemingly continual onslaught of heavy snow and high winds. Get ready, it looks like we’re about to get hammered again. Several steep slopes avalanched this past week, many ran the entire distance of the path and most involved the entire snowpack at least down to the ice crust that formed in early December. Some of these avalanches were visible from the valley floor in the Bitterroot Saturday. We continue to receive great reports from many individuals nearly all of whom witnessed avalanches small and large in many areas of Western Montana up to Saturday.

Conditions improved Saturday as skies cleared and temperatures dropped into the teens giving the snow a chance to adjust. On Sunday, our observers reported that conditions are slowly starting to improve but remain dangerous on the steeper slopes. The deeply buried facets are no longer affected by cold temperatures and are showing signs of strengthening but are still a prominent weakness. It’s getting more difficult to produce failures at this level but when it fails it fails with some energy. It’s as if it can’t wait to bust out and shed all the weight it’s trying to support.

Snow is beginning to fall this morning and many areas can expect to see significant accumulation by Tuesday.

Current Avalanche Danger

The avalanche danger is CONSIDERABLE above 5000′ on all aspects and slopes steeper than 30°. Recently wind loaded or unanchored open slopes remain dangerous. Natural avalanches are possible, human triggered avalanches probable. There are unstable slabs on many slopes just waiting for the right trigger to rip them out. Considerable avalanche danger means there are dangerous conditions out there. BE CAREFUL!

The avalanche danger is MODERATE at all other locations. Natural avalanches are unlikely but human triggered avalanches are possible.

Weather Forecast and Avalanche Outlook

From the Missoula NOAA National Weather Service Forecast Office:
LOWER CLARK FORK REGION-
402 AM MST MON JAN 5 2009

A WINTER STORM WARNING REMAINS IN EFFECT UNTIL 11 PM MST THIS
EVENING.

SNOWFALL WILL INCREASE AND INTENSIFY THROUGH THE MORNING AND CONTINUE THROUGH THIS EVENING. TOTAL SNOWFALL ACCUMULATIONS OF 6TO 8 INCHES IN THE VALLEYS AND 12 TO 14 INCHES IN THE HIGHER TERRAIN ARE EXPECTED BY MONDAY EVENING. LOOKOUT PASS WILL BE THE MOST IMPACTED BY THIS STORM. LOCAL GUSTY SOUTHWEST WINDS MAY CAUSE AREAS OF BLOWING AND DRIFTING SNOW.

A WINTER STORM WARNING MEANS SIGNIFICANT AMOUNTS OF SNOW… AND BLOWING SNOW ARE EXPECTED OR OCCURRING. STRONG WINDS ARE ALSO POSSIBLE. THIS WILL MAKE TRAVEL VERY HAZARDOUS OR IMPOSSIBLE.

Expect avalanche danger to worsen during this storm system. Each new load brings stability back to the tipping point. This is still a dangerous time in the mountains. Slab avalanches involving the newest snow may step down to more deeply buried weaknesses once they start moving.

21 people have died in avalanches this year in the US and Canada, most of them in the past week. Avoid travel on or under slopes steeper than 30°, never expose more than 1 person at a time to an avalanche path, carry rescue equipment and know how to use it.

SPECIAL NOTE: Many mountain ranges in Montana and Northern Idaho are not covered by avalanche advisories. Many of these areas are as popular and visited as often as the mountain ranges covered by the Avalanche Centers in this region. Backcountry recreationists seeking information about avalanche conditions in these areas should contact the local Forest Service District Office for more information. You can also interpret information provided by the Avalanche Centers, SNOTEL sites and the National Weather Service weather forecasts to determine what the snowpack conditions are like in areas that are not covered by an avalanche advisory. When avalanche danger conditions are dangerous from one avalanche advisory area to the next, chances are pretty good that mountain ranges that lie between avalanche centers have very similar conditions, particularly those ranges adjacent to covered areas. If uncertain, do call!

SPECIAL NOTE #2: Foothills areas in Western Montana are beginning to accumulate respectable snow depths. While these areas are outside of our avalanche advisory area, these areas have terrain steep enough and avalanches have happened under the right conditions. In January of 1993, a young man died in an avalanche on Mt. Jumbo within sight of East Missoula. It’s worth paying attention to during unusual winter conditions and we have unusual conditions this year.

We’ve received many excellent observations from many different locations the past few days. Your weather and snow observations are very important to us as they help us portray more accurate overall avalanche conditions in our area. Our resources are limited so information about avalanche activity or weather conditions you see may save a life. If you have any information you’d like to share or have questions about anything related to snow safety, please contact us at [email protected]

The next avalanche advisory will be posted Friday January 9th, 2009