The West Central Montana Avalanche Advisory includes an area on the
Bitterroot and Lolo National Forests from Lookout Pass south to Lolo Pass
and on south to Lost Trail Pass and the Rattlesnake Mountains North of
Missoula. This advisory does not apply to operating ski areas.  Snowpack
stability assessments are based on current data gathered on Thursday and
describe conditions that existed at that time. The National Weather
Service, Missoula Office, provides weather information for the time
described.


Snow and weather are dynamic forces that change continually and sometimes
dramatically over short periods of time. Backcountry travelers should be
able to assess current conditions for themselves and plan their routes of
travel accordingly. Backcountry travelers can reduce their exposure to
avalanche hazards by using timbered trails or ridge routes and avoid open
areas with slope angles greater than 35 degrees.


Hello! This is Steve Karkanen from the West Central Montana Avalanche
Center with the weekend avalanche forecast for January 25-27, 2002. The
adjective rating described below is valid until 2400 hrs on 1/25.
Backcountry users can expect similar conditions through the weekend and
will need to make careful assessments of snowpack conditions.


Weather and Snowpack Analysis:


The mountains of West Central Montana have received substantial snowfall
above 5000' this past week. The Lost Trail Pass observation site received
48", Lolo Pass 38", the St. Regis Basin site 43" and the Point Six site
received 54". Most of these systems have come in with temperatures in the
teens and low 20's so the snow has been of a low density that did not add
alot of weight to our existing snowpack. Winds have been strong and steady
all week. At 8000' the average windspeed has been in the 30mph range for
several days. All East to Northeast aspects are loaded heavily. While the
overall snowpack is adjusting to this new load well and has helped to
strengthen the buried surface hoar layer that has been described since the
holidays, this weakness still remains and is the most prominent feature in
the snow profile. In most areas the new snow has bonded well to the older
snow and in a sense has "bridged" over this surface hoar layer. The
exception to this is in areas that have not received as much new snow, that
are sheltered or at lower elevations. Stability testing in these areas
produce failures at the level of this old weakness. We received an
excellent report from touring parties in the Southern Swan near Morrell
Peak. They report that on Southern aspects where the snow has been shallow
prior to this recent storm, the snow readily collapses under the weight of
a skier or snowmobile. They wisely elected not to ski or ride on any
steeper slopes.


At the higher elevations at all other observation sites, stability testing
produces easy failures at a density change about 14" from the snow surface.
Isolated columns of snow fail when stepped on (Rutschblock score = 2,
indicating unstable conditions). This is the result of temperature
differences between the recent storm cycles. These tests do not easily
produce deep failures on the buried surface hoar layer. Temperatures have
risen significantly over the past 24 hours. The storm now over our area is
warmer, wetter and is quickly adding weight to the colder, drier snow. The
forecast calls for several inches of this heavier, denser snow over the
next 24-48 hours.





Avalanche Outlook:


A HIGH avalanche hazard exists on all slopes greater than 30 degrees.
Natural and human triggered avalanches are likely. Unstable slabs are
likely on a variety of aspects and slope angles. Remember this rating
expires after 2400 hrs 1/18. Backcountry users can expect similar
conditions through the weekend. Pay close attention to this weekends
backcountry weather forecast; most avalanches occur during or immediately
after a storm and this storm has all the ingredients that produce an active
avalanche cycle.


Weather Outlook:


The National Weather Service Office in Missoula is again forecasting
significant moisture with the next weather system that will move into our
area this weekend. At 6000"to 8000" the forecast is calling for 8" to 16"
of snow today with temperatures from 26-31 degrees with SW winds at 30-40
mph. Temperatures begin to cool somewhat over the weekend and will be into
the teens by Sunday. Winds will also diminish but will continue to be a
factor for snow-loading leeward slopes. This weather system is gaining
intensity and will bring increased temperatures and higher density snow.
This alone has increased the avalanche hazard.


http://www.wrh.noaa.gov/cgi-bin/getproduct.pl?MSOGTFSABMSO


The next Avalanche Advisory Report will be issued February1, 2002.


Special thanks to Charles at YurtSki for his excellent observations in the
Southern Swan Range.

Steve Karkanen
Lolo IHC Superintendent
National IHC Steering Committee
406-329-3752


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