THIS AVALANCHE ADVISORY EXPIRED ON March 2, 2019 @ 6:36 am
Avalanche Advisory published on March 1, 2019 @ 6:36 am
Issued by Kevin Davis - Idaho Panhandle Avalanche Center

Selkirks/Cabinets

bottom line

Your biggest concern today and this weekend will be windslabs that may be touchy in steeper terrain.  They exist on all aspects and many are very firm and solid.  Be wary of breakable windslabs on steep, convex terrain.  The great sliding conditions continue with cold temperatures and light additions of new snow.  Overall, the upper pack (3-4 feet) is gaining density with depth and is structurally solid.  Get out before the next deep freeze arrives. 

How to read the advisory

Selkirks/Cabinets

How to read the advisory

Your biggest concern today and this weekend will be windslabs that may be touchy in steeper terrain.  They exist on all aspects and many are very firm and solid.  Be wary of breakable windslabs on steep, convex terrain.  The great sliding conditions continue with cold temperatures and light additions of new snow.  Overall, the upper pack (3-4 feet) is gaining density with depth and is structurally solid.  Get out before the next deep freeze arrives. 

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.

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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Windslabs exist on all aspects due to the erratic winds we have experienced recently.  The weekend northerly gale really pounded the northerly aspects and where we were yesterday on Lunch Peak exposed north facing ridgetops were bulletproof.  Below the ridgetop windslabs the snow is less dense but be careful in this density transition zone where those slabs may grade into something you could trigger.  Cornices were most developed on the south side but the windslabs were not as prevalent.  However, you will find windslabs most anywhere so be on the lookout when you get on firmer snow in steep terrain.

Avalanche Problem 2: Persistent Slab
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We did find the mid January surface hoar persistent weak layer (PWL) on a south aspect at 6,000 feet.  It was buried about 3.5 feet deep in the open trees on a gradual slope.  You would never get this weak layer to fail in this terrain but we found it and it did not fail in our stress tests.  We did get it to shear with alot of banging and saw intact surface hoar crystals.  The scenario where you could awaken this dragon is by triggering a large windslab on a steep NE aspect and that stresses the PWL lower on the slope and now you have triggered a very large slide.  Not likely but we need to relate the hazard, however remote.

advisory discussion

This is the last day to submit your essay for the Doug Abromeit Avalanche Scholarship.  If you're between the ages of 14 and 24 you'd better get writing!  We don't have many submissions so if you're an aspiring Thoreau you have a good chance at scoring a free avalanche class for next year.  

recent observations

No observations of avalanche activity yesterday nor this week from our region up north.  Cornices are well-developed in places so watch your proximity to the edge.  Cornice build up was rapid this week so they are likely to be unsupportive near the edges.

Weather and CURRENT CONDITIONS
weather summary

Jeff and I found about 3-4 inches of new snow from Wednesday night and it was snowing lightly on Lunch Peak all day.  The new snow was very light and falling on about 8 inches of snow that fell Sunday night and Monday.  This made for some very pleasant surface conditions.  Traveling along the ridges though was interesting moving from shin deep powder to rock hard windslabs with no warning.  You"ll find fun and challenging riding too busting through drifts that are built up like a terrain park.  Just watch your slope angles if you're on a hillside.  Not too much more snow fell last night but there may be an inch or so more of light feathers on top.  Milder conditions prevail today but Old Man Winter is back tonight letting us know who's in charge.  Temps will plunge again as the prevailing winds change to the NNE.

Weather observations from the Region
0600 temperature: 10 deg. F.
Max. temperature in the last 24 hours: 18 deg. F.
Average wind direction during the last 24 hours: NW
Average wind speed during the last 24 hours: 5 mph
Maximum wind gust in the last 24 hours: 6 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 115 inches
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.