THIS AVALANCHE ADVISORY EXPIRED ON December 28, 2019 @ 5:40 am
Avalanche Advisory published on December 27, 2019 @ 5:40 am
Issued by Ben Bernall - Kootenai National Forest

Kootenai

bottom line

The snowpack has bonded well after last weeks storm. The biggest threat right now will be small windslabs in steep terrain at elevations above 6,500' on northeasterly terrain near ridgelines. Continue to use caution in high terrain where the snowpack appears to be thin and rocky as these may be locations where deeper weak layers may be senstitive to human triggers.

How to read the advisory

The snowpack has bonded well after last weeks storm. The biggest threat right now will be small windslabs in steep terrain at elevations above 6,500' on northeasterly terrain near ridgelines. Continue to use caution in high terrain where the snowpack appears to be thin and rocky as these may be locations where deeper weak layers may be senstitive to human triggers.

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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We are still finding small pockets of windslabs on north and east aspects on high terrain above 6,500'.  With more southwest winds and light snow in the forecast this problem will remain a possible hazard. Since they are likely to be small in nature the primary concern will be the potential to take a ride in high consequence terrain where a small slide can cause big injuries (cliffs, trees and steep chutes).

Avalanche Problem 2: Persistent Slab
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The deeply buried weak layers consisting of crusts and sugary snow are still down there. They are unlikely to be triggered but worth thinking about if you are riding in steep terrain that is rocky and has thin coverage. Below 6,000' of elevation this weak layer is likely bridged by last weeks rain crust or already slid during the rainy and warm weather. Multiple avalanche crowns were observed in the East Cabinets that released on this weak layer during the storm last weekend.

advisory discussion

On Monday I observed multiple avalanche crowns at the elevation band between 6,000' and 6,500' that released during the warm rainy weather last weekend. Most appeared to have slid on the deeply buried weak layers at the base of our snowpack. These layers are hard to predict when it come to human triggers; but, the easy part is when the weather makes it inevitable. Just remember that drastic change in weather usually causes a spike in avalanche danger. Heavy loading of storm snow, strong winds and warm temperatures are all no-brainers when it comes to avalanche danger.

We are now in a period of fairly uneventful weather that has allowed last weeks snow to settle and bond. With a little fresh snow and continued southwest winds you can expect to see some small slabs cut loose in steep and northeasterly terrain. Nate observed one small and recent avalanche crown in the West Cabinets yesterday that was a result of these steady winds and loose snow. 



Cornice development forming on north and easterly terrain resulting from steady southwest winds this past week.

Weather and CURRENT CONDITIONS
weather summary 
Backcountry Forecast from NWS Missoula issued:
340 AM MST Fri Dec 27 2019

DISCUSSION: A disturbance moving through today will cause abundant
light snow showers that will linger through tonight. There is the
potential of a few loosely organized snow bands setting up late 
this afternoon and evening. Ridgetop winds will also be stronger
today compared to recent days. After a brief break on Saturday, a
similar widespread light snowfall event is expected on Sunday. 



Kootenai:

--------------------------- 5000-7000 FT ----------------------------
                      Today        Tonight      Sat      
Cloud Cover           85%          55%          30%      
Hi/Lo Temps           20 to 26     10 to 18     19 to 26 
Winds(mph)            SW 14G31     W 12G25      W  8G20  
Precip Chc            70           0            0        
Precip Type           snow         snow         none     
Liquid Amt            0.05         0.00         0.00     
Snow Ratio(SLR)       21:1         21:1         0        
Snow Amt(in)          0-3          0            0        

Snow Level            1000         500          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.