THIS AVALANCHE ADVISORY EXPIRED ON March 3, 2018 @ 6:54 am
Avalanche Advisory published on March 2, 2018 @ 6:54 am
Issued by Kevin Davis - Idaho Panhandle Avalanche Center

Selkirks/Cabinets

bottom line

Stability issues from wind effected snow will be your main concern today.  Mountains picked up a couple inches.  Temperatures in the mountains remained below freezing and surface snow will be easily transported by the forecast winds today and tonight.  New snow is expected and this will also add to stress on windloaded aspects.  You'll find good traveling in most terrain but remain cautious of steep lee aspects with cornice formation and sparse vegetation to protect from triggering unstable wind slabs.

How to read the advisory

Selkirks/Cabinets

How to read the advisory

Stability issues from wind effected snow will be your main concern today.  Mountains picked up a couple inches.  Temperatures in the mountains remained below freezing and surface snow will be easily transported by the forecast winds today and tonight.  New snow is expected and this will also add to stress on windloaded aspects.  You'll find good traveling in most terrain but remain cautious of steep lee aspects with cornice formation and sparse vegetation to protect from triggering unstable wind slabs.

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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In the Cabinet Mountains yesterday we found a right side up pack in the upper 4 feet.  The snow showed increasing density with depth which is a stable scenario.  Some weakness existed in the upper 10 inches of recent snow but was not heavy or cohesive enough to be a problem yet.  The conditions yesterday made for great traveling with only minor stability concerns on most terrain choices.  We did avoid steep, open aspects and windloaded aspects where denser surface snow conditions existed.  Winds will continue to load easterly aspects with new snow and transported surface snow.  Windloaded pockets could become very deep and unstable.  Be active in looking for signs of instability.

Avalanche Problem 2: Storm Slab
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Surface snow was very low density grading to more dense snow down to about 3 feet in depth.  We did find a stubborn weak layer buried 2.5 feet deep that sheared cleanly but needed a big nudge to fail.  The overlying slab is dense enough to fail as a larger avalanche.  The most likely places to trigger this problem are windloaded aspects at upper elevations on open, exposed slopes steeper than 30 degrees.  With new snow load and more importantly windloaded snow this should be on your mind if you get into bigger, high elevation terrain.

recent observations

Recent observations are mainly of a steadily deepening pack from consistent stroms and snowfall.  Low temperatures and gradual accumulation have had a settling effect on the pack.  In contrast to this is the effect of windloading which has loaded easterly aspects and unstable pockets of windloaded snow exist.  Cornices are presently unstable.  A deeper weak layer exists at 2.5 feet deep from unsettled snow that fell late last week.  No observations of natural or human triggered avalanches have been reported to IPAC.  Mostly good sliding out there right now but there are places you should avoid for the next several days.  Where we dug at 6,000 feet there was 10 feet of total snow depth.

Weather and CURRENT CONDITIONS
weather summary
New snow, conitnued cold, and westerly winds will effect snow stability today and tomorrow.  Not alot of new snow is expected but anticipate that winds will have the potential to transport light surface snow and load lee aspects.  

 
Weather observations from the Region
0600 temperature: 27 deg. F.
Max. temperature in the last 24 hours: 28 deg. F.
Average wind direction during the last 24 hours: West
Average wind speed during the last 24 hours: light mph
Maximum wind gust in the last 24 hours: 9 mph
New snowfall in the last 24 hours: 2 inches
Total snow depth: 10 feet inches
Two-Day Mountain Weather Forecast Produced in partnership with the Spokane NWS
For 2000 ft. to 4000 ft.
Friday Friday Night Saturday
Weather:
Temperatures: deg. F. deg. F. deg. F.
Wind Direction:
Wind Speed:
Expected snowfall: in. in. in.
For 4000 ft. to 6000 ft.
Friday Friday Night Saturday
Weather: Snow, mainly before 4pm. High near 23. Southeast wind 9 to 16 mph becoming southwest in the afternoon. Winds could gust as high as 24 mph. Chance of precipitation is 90%. Total daytime snow accumulation of 2 to 4 inches possible. A 40 percent chance of snow, mainly before 10pm. Cloudy, with a low around 18. Southwest wind 9 to 11 mph. New snow accumulation of less than one inch possible. A 20 percent chance of snow before 10am. Mostly cloudy, with a high near 23. Southwest wind around 8 mph.
Temperatures: 23 deg. F. 18 deg. F. 23 deg. F.
Wind Direction: SE SW SW
Wind Speed: 9-16 9-11 8
Expected snowfall: 2-4 in. Less than 1 in. in.
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.