THIS AVALANCHE ADVISORY EXPIRED ON March 16, 2019 @ 5:23 am
Avalanche Advisory published on March 15, 2019 @ 5:23 am
Issued by Ben Bernall - Kootenai National Forest

Kootenai

bottom line

The primary weakness right now is 11" below the surface. It will likely cause problems in isolated locations or on slopes that are exposed to the heat of the sun. Asses the stability and consequence of steep slopes individually before diving in headfirst. Now that is is March pay attention to the effects of the sun and move off of steep slopes that are exposed to the sun as the days heat up! 

How to read the advisory

The primary weakness right now is 11" below the surface. It will likely cause problems in isolated locations or on slopes that are exposed to the heat of the sun. Asses the stability and consequence of steep slopes individually before diving in headfirst. Now that is is March pay attention to the effects of the sun and move off of steep slopes that are exposed to the sun as the days heat up! 

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

Yesterday stability tests revealed consistent failures approximately 11" below the surface underneath last weeks (March 6th) storm snow. Tests produced failures with moderate force and most did not propagate. Except one, on a southeast aspect. This is worth paying attention to. Throughout the day we had stable results in pits and nothing reacted underfoot on steep test slopes which made me pretty confident about the mentioned weakness. The 3rd pit at the end of the day did propagate (ECTP13) and brought me back to the reality of how a persistent weakness can vary across the terrain and find a way to surprise you. Take home: it is likely this layer won't respond in pits or under your machine and you may get comfortable pushing your luck; until you find the right spot. Take time to check out individual slopes in steep and high consequence terrain before charging in.

Avalanche Problem 2: Loose Wet
  • Type ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

It's March and the temperatures are starting to climb up above freezing during the day. Expect to see loose-wet slides on south, west aspects and at lower elevations. When the sun comes out and starts to heat up on these aspects move to the north side of the hill and play in the shade on better snow. These loose-wet snow slides are often small, slow and harmless; however, getting caught by one can entrain you and rake you through trees, rocks or into gullies. Also, with the rising temperatures and afternoon sun be alert to the potential for deeper weak layers such as the previously mentioned slab to fail as the sun weakens the upper snowpack.

Avalanche Problem 3: Wind Slab
  • Type ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Windslabs have been the primary concern the past two weeks, yesterday we observed squirrely winds through out the day but found them to be pretty stubborn and difficult to trigger. I would continue to use caution on this issue in steep leeward terrain below ridgeline and steep chutes that may have been cross-loaded. Stiff and hollow sounding snow will be your obvious clue to their presence.

advisory discussion

Weather and CURRENT CONDITIONS
weather summary
Backcountry Forecast from NWS Missoula issued:
430 AM MDT Fri Mar 15 2019

DISCUSSION: High pressure will build along the west coast this
weekend, then shift over western Montana and central Idaho early
next week. A warming trend will bring temperatures back to near 
normal for this time of year (low 50s in valleys) by early next 
week. Periods of cloud and even a few showers will be possible 
until the ridge shifts over us early next week, most notably on 
Sunday.

Kootenai:
--------------------------- 5000-7000 FT ----------------------------
                      Today        Tonight      Sat      
Cloud Cover           65%          50%          55%      
Hi/Lo Temps           29 to 39     18 to 23     32 to 41 
Winds(mph)            SW 11G26     SW  8G18     S  7G20  
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            2000         2500         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.