Avalanche Advisory published on December 12, 2017 @ 7:19 am
This Avalanche Advisory expires in 5 hours, 46 minutes
This advisory is valid for 24 hours
Issued by Melissa Hendrickson - Idaho Panhandle Avalanche Center

St. Regis Basin/Silver Valley

bottom line

The snow trends in the mountains are currently being driven by the inversion.  Large surface hoar was found on all aspects below 5100' , with smaller hoar found at higher elevations.  Near surface faceting found on all aspects. The pack hasn't changed much since Thursday with some melt freeze crusts forming on the southern aspects at higher elevations.  

How to read the advisory


  • Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

St. Regis Basin/Silver Valley

How to read the advisory

1. Low

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Above Treeline

1. Low

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Near Treeline

1. Low

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Below Treeline

The snow trends in the mountains are currently being driven by the inversion.  Large surface hoar was found on all aspects below 5100' , with smaller hoar found at higher elevations.  Near surface faceting found on all aspects. The pack hasn't changed much since Thursday with some melt freeze crusts forming on the southern aspects at higher elevations.  

  • Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
Avalanche Problem 1: Wet Slab
  • Character ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
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    Small

Solar loading during the inversion temperatures which have hit the 40's at elevation this week have increased the surface melting on solar aspects.  The melting on the surface has increased the amount of water percolating into the snowpack which makes solar aspects more susceptible to loose wet avalanches

advisory discussion

Current snowpack is right side up and most areas have a firm base of snow.  The weakest layer is the layer of facets about 10cm down in the sugary storm snow, which is potential bad news for when we recieve more snow in the (hopefully) near future; this layer won't be supportive enough.  

Thank you Gabe White, IPAC volunteer forecaster for excellent observations.  Check Facebook and Instagram for a photo of the large surface hoar that is being seen in the field. 

CURRENT CONDITIONS Weather observations from the Region
0600 temperature: 33 deg. F.
Max. temperature in the last 24 hours: 46 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 6 mph
Maximum wind gust in the last 24 hours: 9 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 14 inches
weather

A big ridge over the pacific is pushing cold air far south and north around our forecast region.  We continue to sit in a high pressure for the next couple of days with inversion conditions.  Tuesday, Wednesday and Thursday are all mostly sunny with highs in the upper 30's and nighttime lows just below freezing.  Look to Friday for a shift in weather patttern and an increased chance in precipitation.  

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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