THIS AVALANCHE ADVISORY EXPIRED ON January 12, 2019 @ 5:27 am
Avalanche Advisory published on January 11, 2019 @ 5:27 am
Issued by Ben Bernall - Kootenai National Forest

Kootenai

bottom line

Another warm and wet storm has brought high mountain snow above treeline and rain below. Expect to encounter storm slabs above treeline on all aspects and crusty snow conditions below 6,000'. In the Purcell Range continue to keep an eye on the persistent weaknesses at treeline and above. Stability will improve as temperatures drop and the wet snow locks together at lower elevations.

How to read the advisory

Another warm and wet storm has brought high mountain snow above treeline and rain below. Expect to encounter storm slabs above treeline on all aspects and crusty snow conditions below 6,000'. In the Purcell Range continue to keep an eye on the persistent weaknesses at treeline and above. Stability will improve as temperatures drop and the wet snow locks together at lower elevations.

2. Moderate

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

1. Low

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Near Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

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: Storm Slab
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The Kootenai has received multiple doses of heavy storm snow throughout the week. Above 6,000' this new snow will need some time and cooler temperatures to strengthen and bond to the variety of surfaces it has landed on. Below this elevation the rain-soaked snow will lock together as temperatures drop back below the freezing mark.

Avalanche Problem 2: Persistent Slab
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As the temperatures fall and time passes the "persistent slab" problem that I am seeing primarily in the Purcell Range will continue to heal. I continue to mention it due to the fact that these weaknesses will "come alive" so to speak as we undergo weather events like Thursdays'. These high elevation rains and heavy storm loads add weight and decrease strength within the snowpack. The weaknesses we are seeing in the Purcells consist of a layer of buried surface hoar, thin facet layer and weak sugary snow at the base. There was a fatality near Choteau last week on such weak layers. Click the link to see the preliminary report. 

https://www.flatheadavalanche.org/announcements/sun-01062019-2319/avalan...

 

advisory discussion

Yesterday we visited the Eastern Cabinets to check out the weeks storm snow and flounder in the rain. The theme for the day was "the climb up in the rain-soaked snow is really hard; but, at least the skiing will be terrible on the way down." Starting at 4,000 we had temps around 37° and climbed to 5,500' before we transitioned into wet, heavy snow. The snow remained this way up to about 6,200 before it started to cool below the freezing mark.  We dug a pit at 6,300' on a SE aspect in a location that was slightly loaded. At this spot we recorded 124" of total snow-depth. Stability tests revealed fairly stable conditions with a failure 4" below the surface on a density change and 8" down on a crust layer that likely developed during the storm on Wednesday. Nothing really jumped out in stability tests, the real story to take home regarding stability is weather. Lots of new snow fell this week in the Cabinet range, below the 6,000-6,5000' mark it fell with a lot of rain and saturated the snow, as temperatures drop it will lock together and become pretty stable (i.e.-crusty!). Above this mark the snow fell on a variety of surfaces, due to the warm and wet nature of the storm it should bond relatively well. There are always spots though such as firm wind scoured surfaces and lower density snow layers that may provide slicker surfaces to slide on and these will take more time to bond to. The best riding will be found this weekend up high; but, it is also where you may trigger a slide in the new storm snow. Continue to practice safe travel habits and carry the right gear (Shovel, Beacon and Probe!) Click the youtube link below to watch a video of yesterdays conditions.

<iframe width="560" height="315" src="https://www.youtube.com/embed/NYblIyir464" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

 

Weather and CURRENT CONDITIONS
weather summary
Backcountry Forecast from NWS Missoula issued:
500 AM MST Fri Jan 11 2019

DISCUSSION: High pressure and strengthening valley inversions will
establish itself over the region through next Monday or Tuesday. 
Snowfall is not expected through early next week. Winds will be 
generally light. The next potential for significant snows won't be
until next Wednesday or Thursday. 

Kootenai:
--------------------------- 5000-7000 FT ----------------------------
                      Today        Tonight      Sat      
Cloud Cover           50%          50%          40%      
Hi/Lo Temps           30 to 35     14 to 25     30 to 36 
Winds(mph)            SE  7G18     SE  8G18     E  7G18  
Precip Chc            0            0            0        
Precip Type           none         none         none     
Liquid Amt            0.00         0.00         0.00     
Snow Ratio(SLR)       0            0            0        
Snow Amt(in)          0            0            0        

Snow Level            3500         3000         2500     
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.