THIS AVALANCHE ADVISORY EXPIRED ON March 6, 2019 @ 5:07 am
Avalanche Advisory published on March 5, 2019 @ 5:07 am
Issued by Ben Bernall - Kootenai National Forest

Kootenai

bottom line

We are currently enjoying good general snowpack stability with windslab problems on specific terrain features. Strong east winds have loaded west aspects just below ridgelines and cross-loaded chutes on north and south aspects. For the best and safest riding conditions look for soft snow in timbered areas where the surface snow hasn't been hammered by the wind!

How to read the advisory

We are currently enjoying good general snowpack stability with windslab problems on specific terrain features. Strong east winds have loaded west aspects just below ridgelines and cross-loaded chutes on north and south aspects. For the best and safest riding conditions look for soft snow in timbered areas where the surface snow hasn't been hammered by the wind!

2. Moderate

?

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

2. Moderate

?

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

1. Low

?

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
  • Type ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

This past weekend the winds cranked once again out of the north and easterly directions. This wind has left the surface snow of these aspects firm and scoured in open areas exposed to the wind. Small and stubborn pockets of wind slab can be found on west aspects near ridgelines and in cross-loaded chutes on south and north faces in open terrain. These slabs will likely be stiff and difficult to trigger, the photos below exemplify the terrain where you may find trouble if you are looking for it.



Steep terrain with cross-loaded chutes in the West Cabinets.

 

advisory discussion

This past weekend the cold continued and brought with it yet another brutal cold front. The east winds that came with it were quite evident yesterday near open ridgeline terrain in the West Cabinets where the snow had been blasted off of the east faces and deposited into very firm pillows on the west side. As can be seen in the above photos! We covered alot of ground yesterday poking around at windslabs on every aspect and found them to be pretty isolated to the previously mentioned locations, they are also pretty stiff and difficult to trigger. These slabs are like the mule you don't want to ride. You can get on him, and he will likely just stand there. But, if you jump up and down or kick him in the ribs he might just buck you off! It's best to just stay off that stubborn mule because there is some great soft snow still hanging out in protected pockets of timber. It's worth noting that with the cold-front the winds loaded up the opposite side of the ridges that we typically see. Generally our winds come out of the west and southwest and load up the north-east side of the ridges. The photo below displays this atypical scenario where old cornice hangs over the northeast aspect but the surface below it is actually scoured and firm.

While I am using livestock analogies let's talk about the dead horse I have been beating called "Persistent Slab". Right now, the snowpack is showing good general stability. I have been talking about the weaknesses buried in the snowpack for awhile, it's been a couple of weeks since any of these weak layers have really showed potential to react or propagate in stability tests so until a weather change brings them to life I will quit beating the dead horse. In the end, the best way to deal with all the potential problems in the snowpack is to adopt and practice good habits. Travel one at a time across steep terrain, watch your partners from a safe location when high-marking or skiing steep terrain and always ride with a beacon, shovel and probe. There will always be a hazard out there in the mountains so be prepared and mitigate it with good habits and good decisions. Thanks for reading and stay warm!

Weather and CURRENT CONDITIONS
weather summary
Backcountry Forecast from NWS Missoula issued:
400 AM MST Tue Mar 5 2019

DISCUSSION: And the cold continues! Luckily though, winds have
diminished and have stayed diminished in most locations, and 
should remain that way through the day. Temperatures will begin to
moderate tonight and Wednesday/Thursday as our next weather- 
making system enters from the south-southwest. Snow levels will 
fluctuate across north central Idaho and across west central 
Montana, but only to about 4500 feet. Freezing rain, or a sloppy
mix of heavy, wet snow and rain is still possible along the
Highway 12 corridor in Idaho and in the Bitterroots of west
central Montana Wednesday. As the cold front moves through early
on Thursday, widespread minor snow accumulations will occur. More
moderate amounts are expected across the Clearwater, 
Kootenai/Cabinet, and Bitterroot mountain ranges. 
-Allegretto

Kootenai:
--------------------------- 5000-7000 FT ----------------------------
                      Today        Tonight      Wed      
Cloud Cover           15%          60%          100%     
Hi/Lo Temps           21 to 28     7 to 15      19 to 26 
Winds(mph)            E  8G20      E 10G25      NE 12G25 
Precip Chc            0            0            40       
Precip Type           none         snow         snow     
Liquid Amt            0.00         0.00         0.09     
Snow Ratio(SLR)       0            17:1         18:1     
Snow Amt(in)          0            0            1-2      
Snow Level            0            500          500      
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.