THIS AVALANCHE ADVISORY EXPIRED ON December 14, 2018 @ 5:10 pm
Avalanche Advisory published on December 13, 2018 @ 5:10 pm
Issued by Eric Morgan - Idaho Panhandle Avalanche Center

Selkirks/Cabinets

bottom line

The avalanche danger is MODERATE with isolated areas of CONSIDERABLE on open windloaded NNE aspects above 35 degrees.  Recent new snow and high winds have loaded up these slopes with 4' + windslabs that sit atop an icecrust in the middle of the pack with surface hoar present a few inches above the crust.  These layers were found on all aspects at 6000 feet.  More snow and winds expected tonight through tomorrow.  

How to read the advisory

Selkirks/Cabinets

How to read the advisory

The avalanche danger is MODERATE with isolated areas of CONSIDERABLE on open windloaded NNE aspects above 35 degrees.  Recent new snow and high winds have loaded up these slopes with 4' + windslabs that sit atop an icecrust in the middle of the pack with surface hoar present a few inches above the crust.  These layers were found on all aspects at 6000 feet.  More snow and winds expected tonight through tomorrow.  

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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Wind drifted snow in the 2-4 feet range has been transported to NEasterly aspects from yesterdays storm.  Open leeward sides of ridgetops should be avoided on steep aspects greater than 35 degrees.  With 3-5 inches of snow expected with transport winds, expect more windloading and watch for storm snow interfaces and how well they bond.  

Avalanche Problem 2: Storm Slab
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13-15 (schweitzer and bear mtn. snotel) plus inches of snow in the past 3 days has created some decent slabs that are in the settling phase.  Watch and listen for cracking and whumphing.  This was observed yesterday in the Selkirks.  This could be a problem in steep terrain where one may get things to move in the right place as this slab settles. 

recent observations

I observed a few feet of recent storm snow in upper elevations in the selkirk range with wind transport slabs in the 4 foot range on extreme ridgetops.  No natural avalanche activity observed but in a shallow pack of 125 cm, there is a small 5cm crust at 65 cm with a light layer consisting of some surface hoar a few cm above the crust that is sensitive with compression tests of CT12 and CT13' s consistently in the storm slab

Explosive triggered avalanches in Lakeview at Schweitzer were observed with 4' crowns that failed on this layer above the crust and stepped down to the crust and in some places ran to the ground.  Note the North Bowl has not been skied yet and is a good indicator of other steep north aspects in the area at this time.  This layer will likely take a little time to heal.  Some whumphing and cracking was observed out toward Uleda throughout the day yesterday with the new storm snow alone.  

Weather and CURRENT CONDITIONS
weather summary

Partly sunny today with 6-16 MPH South winds 26MPH gusts.  

Tonight similar winds with gusts to 41 and 3-5 inches of new snow expected with a temperature down to 22 degrees, then clearing up a bit until another small system moves in the later part of the weekend and strengthening into next week.  High temperatures are expected to be near the freezing mark throughout this time period.  

Weather observations from the Region
0600 temperature: 26 deg. F.
Max. temperature in the last 24 hours: 27 deg. F.
Average wind direction during the last 24 hours: 270
Average wind speed during the last 24 hours: 25 mph
Maximum wind gust in the last 24 hours: mph
New snowfall in the last 24 hours: inches
Total snow depth: 48 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.

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