This is Stan Bones with the backcountry avalanche advisory issued by
   the U.S. Forest Service Glacier Country Avalanche Center at 5:30 AM,
   Friday, December 14, 2007, for the Glacier Park and Flathead and
   Kootenai National Forest areas.

                              HAZARD ANALYSIS

   Between 5,500' and 7,500' elevation the avalanche danger is currently
   rated MODERATE. Below 5,500' the avalanche danger is rated LOW.
   These danger ratings expire at midnight, Friday, December 14th. The
   outlook is for the avalanche danger to increase Friday night and
   through the weekend with increasing snowfall and wind.
   Because of the general nature of this advisory message, each
   backcountry party will always need to make their own time and site
   specific avalanche hazard evaluations.

   WEATHER ANALYSIS: 
   After significant snowfall during the early days of December,
   Northwestern Montana has been relatively dry over the last week.
   During the period snow showers have been scattered with the greatest
   accumulations of a couple of inches occurring Sunday and Tuesday
   night. Over the week temperatures have been cool with readings often
   between 10 and 20 F, with some locations earlier in the week even
   dipping to subzero under clear night skies. Winds have been most
   evident along the Continental Divide, while further west in the
   Kootenai country, winds have generally been lighter.
   SNOWPACK ANALYSIS: 
   Our backcountry observations Thursday were in the Marias Pass area
   along the southern edge of Glacier Park, on the southern divide of the
   East Cabinets in the Kootenai, and in the Noisy Basin area of the
   northern Swan Range NE of Bigfork. In all locations we continue to
   find snowpack depths well below normal.

   Snowpit investigations are often finding low density, loosely bonded
   snow at the snow surface. In the more wind favored areas the surface
   powder snow has been scoured and redeposited onto the leeward side of
   peaks and ridges, forming more dense wind slabs. The mid layers of the
   snowpack is mostly made of melt-freeze ice, while at the base we are
   typically finding weakly bonded, faceted grains.

   In areas of wind deposit, shear tests were often failing easily upon
   the buried mid pack, melt-freeze ice and at the base of the surface
   wind slab. The second plane of weakness we were typically finding is
   at the base of the melt-freeze ice. Although this icy layer typically
   shows significant tensile strength, once that strength is compromised,
   shear failure occurs easily in the faceted grains at the ground
   surface.

   We are seeing a gradual metamorphic weakening of the region's snowpack
   because of it shallowness and the persisting cool air temperatures.
   AVALANCHE - INSTABILITY DESCRIPTION: 
   We're currently rating the avalanche danger between the elevations of
   5,500 and 7,500' as MODERATE on steep, open, unanchored slopes.
   Particularly on recently wind loaded aspects, unstable slab layers are
   possible. Natural avalanches are unlikely, but human triggered
   avalanches are possible. Backcountry travelers should use caution on
   steep, open terrain. Isolated pockets of open snow currently stand out
   invitingly and in contrast to the wide expanses of brush and other
   exposed snow surface anchors.
   Below 5,500 ft. elevation we're rating the avalanche danger as LOW.
   Shallow snow there is often anchored by vegetation and terrain
   features and generally stable with only isolated areas of instability.
   Natural avalanches are very unlikely, while human triggered avalanches
   are unlikely. Backcountry travel is generally safe, but normal caution
   is still advised on any steep, open slope. 
   WEATHER FORECAST & AVALANCHE OUTLOOK:

   
   The weather forecast is for weak high pressure to build over NW
   Montana Friday. A vigorous Pacific weather system should impact the
   area Friday night and Saturday, producing significant precipitation
   and wind, spelling an increase in the avalanche danger this weekend.
   The most new snow accumulation is expected Saturday with 2-8 inches
   possible. Winds are also forecasted to be at their strongest on
   Saturday blowing from the W-SW near 20 MPH. Daytime high temperatures
   should gradually increase through the weekend reaching into the upper
   20's in the mountains Saturday and Sunday.
   New snowfall, increasing winds, and slightly warming temperatures are
   expected to produce an increase in the avalanche danger this weekend.
   Backcountry travelers should be alert to increasing instability
   particularly with steep, unanchored, wind loaded slopes. With our
   below normal snow depths currently, these open slopes will stand out,
   enticingly to backcountry recreationists.
   The next regularly scheduled update of this advisory message will be
   Friday, December 21st.