THIS AVALANCHE ADVISORY EXPIRED ON March 10, 2018 @ 6:31 am
Avalanche Advisory published on March 9, 2018 @ 6:31 am
Issued by Jeff Thompson - Idaho Panhandle Avalanche Center

Selkirks/Cabinets

bottom line

A winter storm has produced snow, rain and wind across the forecast area. 6-8'' of snow has fallen above 4800', but has been moved around with the wind.  The winds were primarily out of the SW which means the E-N faces could have significant wind loading. Expect the storm slab at higher elevations to be reactive. Natural avalanches are possible and human triggered avalanches are likely on slopes steeper than 35 degrees. Make good decisions and travel safely.

How to read the advisory

Selkirks/Cabinets

How to read the advisory

A winter storm has produced snow, rain and wind across the forecast area. 6-8'' of snow has fallen above 4800', but has been moved around with the wind.  The winds were primarily out of the SW which means the E-N faces could have significant wind loading. Expect the storm slab at higher elevations to be reactive. Natural avalanches are possible and human triggered avalanches are likely on slopes steeper than 35 degrees. Make good decisions and travel safely.

3. Considerable

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Above Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

2. Moderate

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

2. Moderate

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Below Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
    Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
Avalanche Problem 1: Storm Slab
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    Certain
    Very Likely
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    Possible
    Unlikely
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With 6-8'' of new snow and strong SW wind overnight, expect the storm slabs to be really reactive. This storm deposited it's snow on top of a loose unconsolidated layer which was sitting on a firm layer of snow. I would expect the new snow to avalanche on the firm snow interface about 12-18'' deep. 

Avalanche Problem 2: Persistent Slab
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There's a crust layer buried about 4' deep in the snowpack that's a concern. The more weight that layer gets on top of it, the closer it will get to the tipping point. The layer is reactive but difficult to trigger. If that crust layer did fail it would produce very large avalanches.  The most likely way to triggered it would be, finding a thinner spot in the snowpack, or to impact that layer by digging deep into the snowpack while traveling (getting a snowmobile stuck in a avalanche zone or leaving a deep trench with the track).  Have a heightened concern for this layer on newly wind loaded slopes.

Weather and CURRENT CONDITIONS
weather summary

This storm is going to pack a punch across the Panhandle, but will be short lived. Look for this system to move out by midnight tonight. A high pressure will follow starting Saturday.  Expect to see sunshine and warm temps. Saturday through next Thursday. It looks like Spring might actually show up!

Weather observations from the Region
0600 temperature: 33 deg. F.
Max. temperature in the last 24 hours: 38 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 20+ mph
Maximum wind gust in the last 24 hours: 61 mph
New snowfall in the last 24 hours: 6 inches
Total snow depth: 133 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Spokane NWS
For 2000 ft. to 4000 ft.
Friday Friday Night Saturday
Weather: Rain Rain Sun
Temperatures: 40 deg. F. 28 deg. F. 44 deg. F.
Wind Direction: SW SW SW
Wind Speed: 12-14 10-13 3-5
Expected snowfall: 0 in. 0 in. 0 in.
For 4000 ft. to 6000 ft.
Friday Friday Night Saturday
Weather: Snow Partly cloudy Sun
Temperatures: 32 deg. F. 23 deg. F. 36 deg. F.
Wind Direction: SW SW E
Wind Speed: 20-25 G50 10-12 G22 8-103-5
Expected snowfall: 3-5 in. >1'' in. 0 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.