THIS AVALANCHE ADVISORY EXPIRED ON March 21, 2018 @ 5:32 am
Avalanche Advisory published on March 20, 2018 @ 5:32 am
Issued by Ben Bernall - Kootenai National Forest

Kootenai

bottom line

Generally stable snowpack conditions exist in the mountains of the Kootenai. Use caution in steep, unsupported terrain on northeasterly aspects above 6,000' where isolated windslabs may persist.  Expect to see small "loose-wet" avalanches form on slopes exposed to solar radiation as the weather forecast is calling for partly sunny conditions through Wednesday.

How to read the advisory

Generally stable snowpack conditions exist in the mountains of the Kootenai. Use caution in steep, unsupported terrain on northeasterly aspects above 6,000' where isolated windslabs may persist.  Expect to see small "loose-wet" avalanches form on slopes exposed to solar radiation as the weather forecast is calling for partly sunny conditions through Wednesday.

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: Wind Slab
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Yesterday we observed small, isolated wind slabs adjacent to ridgelines on northeasterly aspects. These slabs are most likely to be hazardous at upper elevations and in "extreme" terrain. Use caution before committing to steep and unsupported slopes on these aspects above 6,000'.



Small windslab on Northeast aspect in East Cabinets. 10-12" thick directly below ridgeline.

Avalanche Problem 2: Loose Wet
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There is a thin layer of new snow overlying crust on solar aspects. Weather forecasts are predicting partly sunny conditions Tuesday and Wednesday. We can expect this new snow to flow down the hill in the form of "wet-loose" avalanches on any aspects receiving solar radiation. These slides are likely to be small in nature but worth paying attention to in areas above high consequence terrain such as cliffs, gullies and trees. Pay attention to the sun this week and look for better riding conditions on northerly aspects.

advisory discussion

On Monday we travelled into the East Cabinets with Kevin Davis from IPAC. We observed a small isolated windslabs on northeast aspects, old avalanche debris from last weeks warm sunny days and a generally stable mountain snowpack. Stability tests revealed a consistent weakness 11" below the surface that failed with hard force and low likelihood of propagation. This weakness has been observed across the area for the past week and is resting under the snow that came in March 8th and 9th. This layer and the February 4th rain crust are prevalant weak layers that are being watched; but, they are unlikely to cause an issue for riders unless we experience a radical change in weather such as high elevation rain or multiple days and nights of warm temperatures.  As I mentioned last week these weaknesses are likely to be more of an issue in the thin snowpack of the Purcell Range. Otherwise, generally stable conditions persist with low avalanche danger at treeline and below. The upper elevations are being rated as moderate primarily due to the potential to trigger windslabs in extreme terrain on northeasterly aspects

Looking forward into the week the National Weather Service is calling for the potential of a significant moisture event coming into the mountains of Northwest Montana so stay tuned for a potential change on Thursday!

Weather and CURRENT CONDITIONS
weather summary
Backcountry Forecast from NWS Missoula issued:
330 AM MDT Tue Mar 20 2018

DISCUSSION: Occasional snow showers are expected on the terrain
today and Wednesday but accumulations will be minimal. Winds will
be light overall, but the higher terrain of Northwest Montana may
see southwesterly gusts to 25 mph from time to time.

The next weather system with widespread precipitation and breezy
winds will be later Thursday into Friday. Snow levels will start 
off relatively high, then drop to valleys floors behind a cold 
front Friday into Saturday. Cool and showery weather will 
continue into the coming weekend. 

Kootenai:
--------------------------- 5000-7000 FT ----------------------------
                      Today        Tonight      Wed      
Cloud Cover           75%          65%          75%      
Hi/Lo Temps           35 to 44     22 to 27     39 to 45 
Winds(mph)            SW  9        SW  7        S  5     
Precip Chc            0            0            40       
Precip Type           showers      sno/shr      showers  
Liquid Amt            0.00         0.00         0.03     
Snow Ratio(SLR)       15:1         14:1         14:1     
Snow Amt(in)          0            0            0        
Snow Level            2500         3000         3000     
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.