This is Tony Willits with the backcountry avalanche advisory issued by the U.S. Forest Service 
Glacier Country Avalanche Center at 8:00 AM, Friday, March 26th for Glacier Park, Flathead and 
Kootenai National Forest areas. 

HAZARD ANALYSIS

During periods of thaw between the elevations of 5,000 and 7,500 ft. we rate the wet snow avalanche 
danger CONSIDERABLE.

The dry snow avalanche danger between the elevations of 5,000 and 7,500 ft. is currently being rated 
MODERATE on all large, steep, open slopes lacking vegetative and terrain anchors. As well during dry 
snow periods, on anchored slopes below 7,500 ft. and all slopes, all aspects, below 5,000 ft., we're 
rating the avalanche danger as LOW.   

These danger ratings expire at midnight, Friday, March 26th.  The outlook is for the avalanche danger 
to remain at current levels through the weekend.

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:
 
Since 1500 Thursday afternoon, light snow accumulations were received at most electronic sites with
 .1 to .2 of additional snow water equivalent.  Temperatures overnight were just below freezing at 
 most sites.  Significant freezing did occur Tuesday and Wednesday nights and helped solidify surface 
layers.  Ridge top winds picked up on Thursday afternoon as a system moved through our region.

SNOWPACK ANALYSIS:

Our backcountry observations on Thursday, were from along the Swan Crest near Doris Creek on the 
Flathead National Forest and from Mount Henry in the Purcells on the Kootenai National Forest. As 
well, we received an observation from some riders north of Therriault Lakes.

The solid refreezing that occurred overnight Wednesday allowed for good travel conditions on Thursday.  
Tuesday's and Wednesday's blue skies encouraged point releases and roller ball activity on all aspects 
except hard shaded northern aspects, although no new natural slab activity was noted. Any solar 
influence seems to promote most snow surfaces to crust over although hard north aspects remained soft 
at upper elevations. 

Observations indicated weak interfaces lingering on from buried surface hoar layers and thin faceted 
layers just above or below melt freeze crusts that propagated during extended column tests releasing 
as deep as 70 cms below the snow surface.  These weak interfaces would be more of a concern on steep 
open unanchored slopes.  As an example of the existence of these weak interfaces, on Wednesday some 
snowmobilers, north of Therriault Lakes, triggered a small slab avalanche where no one was caught or 
injured.
               
AVALANCHE - INSTABILITY DESCRIPTION:

During periods of thaw

... we rate the wet snow avalanche danger as CONSIDERABLE between the elevations of 5,000 and 7,500 ft.  
where particularly on steep Serly facing slopes with both unstable loose wet surface snow and 
unstable deeper slab layers are probable.  Both natural and human triggered avalanches are possible.  
Backcountry travelers should be very cautious in steeper terrain during periods of thaw, especially 
that temperatures climb into the 40's and/or when nighttime freezing fails to occur.  Be aware of 
potentially dangerous areas of unstable heavy wet snow especially during rain events.

During periods of solid refreezing and dry snow conditions...we're currently rating the avalanche 
danger between the elevations of 5,000 and 7,500 ft. as MODERATE on all large, steep, open slopes 
lacking vegetative and terrain anchors. Unstable deep slab layers are possible. Natural avalanches 
are unlikely, but human triggered avalanches remain possible. Backcountry travelers should use caution 
in big, steep, open terrain on all aspects.

As well, during periods of solid refreezing and dry snow conditions...on anchored slopes below 
7,500 ft. and all slopes, all aspects, below 5,000 ft., we're rating the avalanche danger as LOW. The 
anchored or shallow snow there is generally stable with only isolated areas of instability. Natural 
avalanches are very unlikely, while human triggered avalanches are unlikely. Backcountry travel is 
generally safe. Normal caution is advised. Backcountry travelers need to always realize that LOW 
avalanche danger is not the same as NO avalanche danger.

WEATHER FORECAST & AVALANCHE OUTLOOK:
`
Current Western Montana NWS Backcountry Weather Forecast.

A Pacific storm system will bring a long duration of light and intermittent snow events to the 
Northern Rockies through early Saturday.  Area mountain passes could possibly receive up to 6 inches 
of new accumulations during this period.  Expect snow showers to cease by Saturday with warming 
temperatures as high pressure returns to the region.   

Avoid playing on solar aspects as temperatures warm and just get out of Dodge if precipe happens to 
turn to rain.  Unstable surface layers are lingering and cutting into them is easier as climbing 
higher and higher is made possible with our settled conditions.  
 
Please note that this avalanche advisory is our best interpretation of snow pack conditions and 
National Weather Service Forecasts on the day the advisory is issued. Unanticipated weather changes 
such as wind, a marked temperature increase, or precipitation beyond forecast amounts can increase 
the avalanche danger. Local variations may also exist. 

The next avalanche advisory will be on Friday, April 2nd, 2010.