THIS AVALANCHE ADVISORY EXPIRED ON January 6, 2018 @ 6:48 am
Avalanche Advisory published on January 5, 2018 @ 6:48 am
Issued by Melissa Hendrickson - Idaho Panhandle Avalanche Center

St. Regis Basin/Silver Valley

bottom line

This week has seen clear skies and gradual improvement in stability with another cycle of surface hoar development on the denser layer from the 12/30 storm (note: first hand inspection, this is not a full on rain crust).  All the new loading of the past two weeks has buried the persistent layer under 2 to 3 feet of snow and even deeper in windloaded areas. Be cautious of this layer as a slide of this depth would be catastrophic.  

How to read the advisory

St. Regis Basin/Silver Valley

How to read the advisory

This week has seen clear skies and gradual improvement in stability with another cycle of surface hoar development on the denser layer from the 12/30 storm (note: first hand inspection, this is not a full on rain crust).  All the new loading of the past two weeks has buried the persistent layer under 2 to 3 feet of snow and even deeper in windloaded areas. Be cautious of this layer as a slide of this depth would be catastrophic.  

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.

2. Moderate

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Below Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
    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 and crossloading are widespread on and near the ridgelines.  

Avalanche Problem 2: Deep Slab
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Susceptible to human triggers in shallow areas. Cautious assessment of terrain is required. 

Avalanche Problem 3: Loose Dry
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Surface hoar growth and recent small amounts of precipitation sit on the denser 12/30 surface.  Human triggered point releases have the potential to create small, loose slides

recent observations

We travelled to the St. Regis/ Steven's Lake Divide yesterday.  We found that the snowpack is gaining stability on all aspects, but windslabs are still a concern at the higher elevations.  Windloading from the last storm was prevalent and widespread, although shows evidence of rounding and gaining strength.  We were also able to observe several avalanche paths from previously in the week.  One large D3 path was observed that stepped down to the Thanksgiving crust.  The dense layer of snow from the 12/30 storm (still not saying crust), was bridging our weight on cross country travel.  That paired with the surface hoar formation on top will be something to keep an eye on as our next system rolls in. 

Weather and CURRENT CONDITIONS
Weather observations from the Region
0600 temperature: 31 deg. F.
Max. temperature in the last 24 hours: 32 deg. F.
Average wind direction during the last 24 hours: S
Average wind speed during the last 24 hours: 6 mph
Maximum wind gust in the last 24 hours: 8 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 44 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Spokane NWS
For 2000 ft. to 4000 ft.
Friday Friday Night Saturday
Weather: Chance of Rain/Snow then chance of rain Rain then rain/snow Snow then chance of snow
Temperatures: 33 deg. F. 31 deg. F. 32 deg. F.
Wind Direction: E SW SW
Wind Speed: 6 7 8
Expected snowfall: <.5 in. 1 in. 1-3 in.
For 4000 ft. to 6000 ft.
Friday Friday Night Saturday
Weather: Chance of Rain/Snow then chance rain Rain/snow Snow then snow likely
Temperatures: 34 deg. F. 28 deg. F. 31 and dropping deg. F.
Wind Direction: SW SW W
Wind Speed: 9 10-14 14
Expected snowfall: <.1 in. 1-3 in. 1-3 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.