THIS AVALANCHE ADVISORY EXPIRED ON March 21, 2020 @ 5:15 am
Avalanche Advisory published on March 20, 2020 @ 5:15 am
Issued by Ben Bernall - Kootenai National Forest

Kootenai

bottom line

New snow from last weekends storm will be your main concern right now. In very steep terrain (over 35°) it will be possible to trigger avalanches in the upper 6-10" of the snowpack. On due north aspects these slides will come in the form of loose-dry slough or thin soft slabs. On solar aspects expect to trigger wet slides in steep terrain as the afternoon sun warms the surface.

How to read the advisory

New snow from last weekends storm will be your main concern right now. In very steep terrain (over 35°) it will be possible to trigger avalanches in the upper 6-10" of the snowpack. On due north aspects these slides will come in the form of loose-dry slough or thin soft slabs. On solar aspects expect to trigger wet slides in steep terrain as the afternoon sun warms the surface.

2. Moderate

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Above Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

2. Moderate

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Near Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

1. Low

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Below Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
    Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1: Loose Wet
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The most recent storm snow is resting on a firm surface on south and westerly aspects. With sunny days ahead expect to see small surface slides as it warms up in steep terrain. Yesterdays observations showed that most of these slides are staying pretty small and mainly found in very steep terrain close to rock outcroppings. As always, pay attention to the terrain below you as these relativiely benign slides can push you off a cliff or into the trees

Avalanche Problem 2: Loose Dry
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The snow on the north side of the hill is staying surprisingly cold and light despite the warm days. Yesterday we observed evidence of multiple "loose-dry" avalanches and thin soft slabs that had released in steep terrain over 40°. These slides were all a result of last weekends storm snow and small in size. They are big enough to push a rider down the hill but not enough to bury you. Again, if you are in steep terrain, take a look at whats below you before committing to a slope.

advisory discussion

What a week!  Instead of freaking out the next couple of days, maybe load up the machine and get into the mountains. The mountains are completely oblivious to the whole Corona Virus madness. 

While you are up there here are a couple of things to keep in mind. The snowpack is pretty stable right now and the primary issues are close to the surface. The top 6-10" of snow are what you need to be thinking about right now and very steep terrain is where it is most likely to move on you. When the afternoon sun starts to cook the slope move to lower angle terrain, or head to the north side where the snow is light and soft (i.e.-FUN!!) As mentioned above, you may see some small slides in steep terrain or convex rolls on these shady aspects where the surface snow is still having a tough time sticking to the slope. The layers of buried surface hoar in the West Cabinets and Purcells are still there but unlikely to give you any trouble at this time so I have taken them off the "PROBLEMS" list.

Yesterdays observations were taken in the East Cabinets. The goal for the day was to cover ground and see how the new snow was reacting and take a look at the potential wind slab issues. The winds cranked last weekend and its' effects were obvious on the surface of the snowpack. Large ripples and pillows of snow could be viewed on open terrain particularly at upper elevations. WIth multiple warm days and cold nights under our belt I think it is unlikely you will have a problem with these wind slabs as they will be pretty stiff and stubborn in the days ahead. Aside from the fairly recent small slides in the surface snow, our other interesting observation was the development of another batch of surface hoar on northerly slopes and sheltered drainage bottoms at mid-elevations. This will be something to watch if it stays preserved and gets buried under the next storm. Time will tell.

I will provide a "Snowpack Summary" on Tuesday morning with no Hazard rating for those of you going out mid-week. The next (and last) advisory for the year will be posted on March 27th. 

Weather and CURRENT CONDITIONS
weather summary 
Backcountry Forecast from NWS Missoula issued:
410 AM MDT Fri Mar 20 2020

DISCUSSION: 
Northwest Montana: Dry northwest flow will bring a slight 
increase in temperatures today and otherwise quiet conditions. The
next chance for precipitation comes Saturday afternoon into 
Sunday morning. Snow levels will linger around 4000 feet during 
the day, lowering to 2000 feet overnight. Light snow accumulations
are possible, particularly in the Flathead/Swan and Glacier Park 
Ranges. Warmer and drier conditions are expected Sunday into 
Monday, before a cold front passes Monday night. Cooler and 
unsettled conditions will then be possible for much of the rest of
the week.
Kootenai:
--------------------------- 5000-7000 FT ----------------------------
                      Today        Tonight      Sat      
Cloud Cover           20%          20%          35%      
Hi/Lo Temps           33 to 40     19 to 25     34 to 42 
Winds(mph)            W  6G16      W  8         W  7     
Precip Chc            0            0            0        
Precip Type           none         none         snow     
Liquid Amt            0.00         0.00         0.00     
Snow Ratio(SLR)       0            0            13:1     
Snow Amt(in)          0            0            0        
Snow Level            3000         4000         3500
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.