THIS AVALANCHE ADVISORY EXPIRED ON January 25, 2020 @ 5:19 am
Avalanche Advisory published on January 24, 2020 @ 5:19 am
Issued by Ben Bernall - Kootenai National Forest

Kootenai

bottom line

Warm temperatures and moisture will continue to add snow to the mountains above 5,000' and rain below. Expect to see small "loose-wet" slides at lower elevations. At upper elevation dense storm slab avalanches are possible in open and steep terrain (over 35°). Primary areas of concern are southerly exposures in the Cabinet Wilderness where the new snow is falling on a sun-crust layer that developed last weekend.

How to read the advisory

Warm temperatures and moisture will continue to add snow to the mountains above 5,000' and rain below. Expect to see small "loose-wet" slides at lower elevations. At upper elevation dense storm slab avalanches are possible in open and steep terrain (over 35°). Primary areas of concern are southerly exposures in the Cabinet Wilderness where the new snow is falling on a sun-crust layer that developed last weekend.

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.

2. Moderate

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Below Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
    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 Cabinets have been picking up steady snowfall since Tuesday night. You are likely to find over a foot of dense new snow that is resting on a thin layer of surface hoar out there. It was not proving to be very reactive under foot or in stability tests yesterday. Places to be leary of are areas of open, steep terrain over 35° and convex rolls. Southerly aspects in the Cabinet Wilderness have a sun crust under this new snow that will make it more likely to slide, those are the spots to avoid. The Purcell Range has seen very little new snow and will have much thinner storm slabs.

Avalanche Problem 2: Loose Wet
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That rain line is gonna bounce up and down around 5,000' feet through the weekend. Expect to see lots of slough and rollers coming down the hill below 5,500'.  While less hazardous than a thick storm slab avalanche it is always worth paying attention to what's below you in steep terrain.

Avalanche Problem 3: Wind Slab
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Southwest winds will continue to blow steady through the weekend. Yesterday the wet dense snow was adhering well and not transporting below 6,500'. At the higher peaks with cooler temperatures I would expect the wind slabs to continue building on northeasterly aspects. Watch for drifted snow and areas below cornices at upper elevations.

advisory discussion

They say the devil is in the details. So, here ya go.

On Monday we were finding sun crust on all open terrain with exposure to the sun and on sheltered terrain in the trees we were finding a thin layer of surface hoar. Since then the West Cabinets have picked up a foot of snow at upper elevations with more coming. The East Cabinets picked up about half that amount and the poor Purcell Range is showing very little in new precip. The new snow came in warm and wet and we observed rain up to 5,700 yesterday before it dropped back to 5,000'. Gross.

It's these bed surfaces of crust and surface hoar that are my main concern going into the weekend. The new snow seems to be bonding pretty well and was not very reactive yesterday despite the buried surface hoar underneath it. I think the most reactive areas will be those southerly aspects in the East Cabinets in steep terrain. Warm temperatures and more weight being added with incoming moisture I am also concerned about anything really steep and open. These steep and open slopes may become more likely to slide as warm temperatures and moisture add stress to the snowpack.

And lastly, with all this dense snow and rain you might want to throw a saw in your pack if heading into the West Cabinets. Just sayin!!

Weather and CURRENT CONDITIONS
weather summary 
Backcountry Forecast from NWS Missoula issued:
340 AM MST Fri Jan 24 2020

DISCUSSION: A weak cold front coming through will cause some snow
and falling snow levels today. Overall, the region will remain
under a moist, southwest flow pattern with above average
temperatures next week. 

Northwest Montana: Saturday night looks like the most likely
period to have super cooled water clouds intersecting the terrain
potentially causing freezing drizzle or riming. Southwest and
westerly slopes are the most likely to be affected due to the wind
direction and orographic lift. With the Saturday night system the
higher snow amounts are expected in the far western parts of
Montana with much less precipitation in the Flathead and along the
Continental Divide.
Kootenai:
--------------------------- 5000-7000 FT ----------------------------
                      Today        Tonight      Sat      
Cloud Cover           95%          85%          95%      
Hi/Lo Temps           32 to 37     26 to 31     29 to 36 
Winds(mph)            SW 17G36     SW 20G36     SW 15G25 
Precip Chc            90           50           40       
Precip Type           sno/fzra     sno/fzra     sno/fzra 
Liquid Amt            0.38         0.12         0.06     
Snow Ratio(SLR)       13:1         16:1         16:1     
Snow Amt(in)          4-10         1-8          1-3      

Snow Level            5000         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.