Avalanche Advisory published on February 22, 2019 @ 5:09 am
This Avalanche Advisory expires in 11 hours, 50 minutes
This advisory is valid for 24 hours
Issued by Ben Bernall - Kootenai National Forest

Kootenai

bottom line

Generally stable snowpack conditions exist right now but there are hazards at isolated locations in steep terrain at treeline and above. Take the time to assess each slope individually before committing to any steep chute or exposed ribs where a small pocket of slab may wreck your day. 

How to read the advisory

Generally stable snowpack conditions exist right now but there are hazards at isolated locations in steep terrain at treeline and above. Take the time to assess each slope individually before committing to any steep chute or exposed ribs where a small pocket of slab may wreck your day. 

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: Wind Slab
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The winds have blown from all directions this past week.  These windslabs have become pretty stiff with the recent strong winds and may be difficult to trigger but should be treated with caution.  Expect to find these slabs on any aspect in steep terrain. Steep, high and open terrain with cross-loaded gullies are where a rider may find trouble this week. See photos below.

Avalanche Problem 2: Persistent Slab
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Yesterdays observations revealed that the recent cold tempertures are starting to drive the faceting process in areas where the snowpack is thinner such as exposed ribs and ridgelines. We are also still finding buried surface hoar out there in isolated locations though it is very stubborn and difficult to trigger at this point. Obvious clues such as collapsing and shooting cracks should alert you to the presence of these weak layers. The best way to avoid triggering this layer will be to avoid steep convex rolls and steep terrain that is likely to have thin snow coverage.

advisory discussion

The storm snow from last week has been blown around in multiple directions for the past week and has either settled or been compressed to the density of a two by four by high winds. Yesterday and Mondays' observations revealed that most of the higher terrain has been hammered by the wind from multiple directions and has created stiff wind slabs. Yesterdays pit results revealed that the main concerns are still the isolated pockets of buried surface hoar and thin layers of facets (weak, sugary snow). Triggering a slide on one of these layers will likely be difficult and you will have to find the "sweet spot" to do it. But, keep an eye out for terrain that is steep and exposed to the winds. These areas where the snowpack is thin are more susceptible to faceting and more susceptible to triggers such as a snowmobiler or skier.

The "persistent slab" problem is unlikely to go away soon with the cold temperatures. Continue to keep it in mind when selecting terrain and pay attention to the obvious clues.  Have fun and stay safe out there!

Weather and CURRENT CONDITIONS
weather summary
Backcountry Forecast from NWS Missoula issued:
420 AM MST Fri Feb 22 2019

DISCUSSION: Many locations are starting the day off a few degrees
below zero this morning, and will be slow to warm during the day.
Our next weather disturbance will begin to spread light to
moderate snow across the region this evening, and continuing
through Saturday. Northwest Montana will see the snow first,
starting around sunset, and will spread from north to south 
across the rest of western Montana by midnight tonight. Several 
inches of mountain snow over the next 24 hours is expected. 
Another system will bring even more snow to the region Sunday 
through Tuesday. Most of the higher accumulations are expected to
be along and south of the I-90 corridor. Where a foot of new snow
in the mountains will not be out of the question.

Kootenai:
--------------------------- 5000-7000 FT ----------------------------
                      Today        Tonight      Sat      
Cloud Cover           80%          90%          85%      
Hi/Lo Temps           18 to 24     11 to 17     20 to 27 
Winds(mph)            SW 16G33     SW 14G36     NW  8G23 
Precip Chc            60           90           80       
Precip Type           snow         snow         snow     
Liquid Amt            0.02         0.19         0.08     
Snow Ratio(SLR)       20:1         20:1         20:1     
Snow Amt(in)          0-1          3-7          1-2      
Snow Level            0            0            0        
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.

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