THIS AVALANCHE ADVISORY EXPIRED ON January 11, 2020 @ 5:02 am
Avalanche Advisory published on January 10, 2020 @ 5:02 am
Issued by Ben Bernall - Kootenai National Forest

Kootenai

bottom line

For Friday the Avalanche Danger will be rated as Considerable with the potential to rise by Saturday morning due to another storm system entering the area. Avoid terrain over 35° particularly on north and east aspects where winds have loaded steep slopes. 

How to read the advisory

For Friday the Avalanche Danger will be rated as Considerable with the potential to rise by Saturday morning due to another storm system entering the area. Avoid terrain over 35° particularly on north and east aspects where winds have loaded steep slopes. 

3. Considerable

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Above Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

3. Considerable

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Near Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

2. Moderate

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Below Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
    Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
Avalanche Problem 1: Storm Slab
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The last round of storm snow has settled and is quckly stabilizing. Another predicted storm will enter the area Friday afternoon and is forecast to bring an additional 1-2 feet of snow near the Idaho/Montana border. This will likely cause the avalanche danger to rise on Saturday and stay elevated throughout the weekend. We were seeing pockets of graupel (small-rounded snow-balls/similiar to hail) near the surface of the snowpack yesterday. This graupel layer will make a poor surface for the next round of storm-snow to adhere to and will likely slide easily when loaded by the next storm.

Avalanche Problem 2: Wind Slab
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We observed numerous wind slabs yesterday on north and east aspects and the winds are predicted to continue with the next storm. Most of the slabs we observed were stiff, stubborn and will be difficult to trigger. However, I would not trust them going into the weekend on steep terrain. If the terrain is steep and has a cornice or wind-lip resting on top of it I would avoid it this weekend as these locations will be your likely "trigger points" for starting an avalanche.

advisory discussion

So, here are the details. Yesterday we toured into the West Cabinets near Benning Mountain to check out the recent storm snow. On the way in we observed multiple crown lines from avalanches that appeared to have released on Tuesday or Wednesday during the storm. We dug multiple pits above the 6,000' elevation and found that the new storm snow had settled quickly and was proving to stabilize quickly. The layers of interest were the graupel near the snowpack surface and two very thin crust layers that are now about 4 feet below the surface. These crust layers were reactive on Monday but were showing very little potential yesterday. Total snow depth on average was about 126 inches on easterly aspects. This last storm varied wildly across the area in snowfall. Snotel sites at Bear Mountain gained around 38" from Sunday to Wednesday, where as the East Cabinets picked up about 22" and the Purcell Range snotels were showing a measily 7-8".

The "big story" right now is the next storm. Weather is always tricky; but, there seems to be a high confidence in the next storm to bring us a good shot of snow on Friday afternoon and continue through the weekend. The storm slab issue is likely to be a serious concern by Saturday and Sunday. It will be a good weekend to play a conservative game when choosing terrain to play in.

David Thompson Search and Rescue is holding an Avalanche Awareness course Friday night at the SAR Barn in Libby with a field day to follow. Show up and refresh your avalanche skills and knowledge for the year!

And lastly, deepest condolence to the friends and family of the recent avalanche victims at Silver Mountain this past week. 

Weather and CURRENT CONDITIONS
weather summary 
Backcountry Forecast from NWS Missoula issued:
DISCUSSION:  
NORTHWEST MONTANA: Snow will return late this afternoon as a 
strong closed low drops down along the Canadian coast and sends 
a surge of Pacific moisture into the region. A period of heavy
snow is expected tonight into Saturday with snow for all
elevations. The heaviest snow is expected in the higher terrain 
near the Idaho panhandle, where 1 to 2 feet of snow is possible.
Westerly winds of 40 mph are possible in the higher terrain, 
generally above 6000 feet. Lighter but persistent snow will likely
continue in the higher terrain through Sunday. A second surge of 
moisture will bring another period of moderate to heavy snow late 
Sunday into Monday. At the same time, an arctic push will drop 
south out of Canada Sunday evening into Monday. How far this 
arctic makes it in to northwest Montana is still questionable, but
there is a high likelihood that it will at least make it as far 
west as the Whitefish Range. Gusty northeast winds and 
significantly colder temperatures are anticipated along this 
boundary. Next week will be much colder with continued periods of
snow. 
Kootenai:
--------------------------- 5000-7000 FT ----------------------------
                      Today        Tonight      Sat      
Cloud Cover           85%          95%          100%     
Hi/Lo Temps           20 to 26     17 to 23     25 to 31 
Winds(mph)            S 18G36      S 20G33      S 14G31  
Precip Chc            100          100          90       
Precip Type           snow         snow         snow     
Liquid Amt            0.15         0.48         0.32     
Snow Ratio(SLR)       21:1         18:1         18:1     
Snow Amt(in)          3-5          8-16         5-12     
Snow Level            0            1500         1500
Disclaimer

Avalanche conditions change for better or worse continually. Backcountry travelers should be prepared to assess current conditions for themselves, plan their routes of travel accordingly, and never travel alone. Backcountry travelers can reduce their exposure to avalanche hazards by utilizing timbered trails and ridge routes and by avoiding open and exposed terrain with slope angles of 30 degrees or more. Backcountry travelers should carry the necessary avalanche rescue equipment such as a shovel, avalanche probe or probe ski poles, a rescue beacon and a well-equipped first aid kit.  For a recorded version of the Avalanche Advisory call (208)765-7323.