THIS AVALANCHE ADVISORY EXPIRED ON December 20, 2017 @ 6:51 am
Avalanche Advisory published on December 19, 2017 @ 6:51 am
Issued by Melissa Hendrickson - Idaho Panhandle Avalanche Center

St. Regis Basin/Silver Valley

bottom line

Heavy snowfall has been and is currently falling on our weak snowpack and will continue through the advisory period with snowfall rates up to 1" to 2" an hour. Avalanche activity is expected to increase during the advisory period.  Windloading has occurred from the N-SE aspects, with extensive windslabs observed at the higher elevations.  Careful snowpack evaluation, cautious route-finding and conservative decision making are essential in the backcountry today. 

How to read the advisory

St. Regis Basin/Silver Valley

How to read the advisory

Heavy snowfall has been and is currently falling on our weak snowpack and will continue through the advisory period with snowfall rates up to 1" to 2" an hour. Avalanche activity is expected to increase during the advisory period.  Windloading has occurred from the N-SE aspects, with extensive windslabs observed at the higher elevations.  Careful snowpack evaluation, cautious route-finding and conservative decision making are essential in the backcountry today. 

4. High

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Above Treeline
Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.

4. High

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Near Treeline
Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.

3. Considerable

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Below Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
    Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
Avalanche Problem 1: Wind Slab
  • Type ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

At higher elevations, wind slabs were observed on all aspects. Shifting winds have created heavy wind loading on N-SE aspects at the mid elevations. 

Avalanche Problem 2: Storm Slab
  • Type ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

A heavy, dense storm slab fueled by strong winds and heavy snowfall will form over the next 48 hours over our weak snowpack. 

advisory discussion

Thank you Gabe White and the Silver Mountain Ski Patrol for providing observations for today's forecast.

recent observations

 Natural avalanches have been observed in the region, and Silver Patrol mitigation triggered firm wind slabs on N aspects that propagated on facets yesterday.

Weather and CURRENT CONDITIONS
Weather observations from the Region
0600 temperature: 30 deg. F.
Max. temperature in the last 24 hours: 32 deg. F.
Average wind direction during the last 24 hours: NW
Average wind speed during the last 24 hours: 10 mph
Maximum wind gust in the last 24 hours: 26 mph
New snowfall in the last 24 hours: 7 - 11" inches
Total snow depth: 22 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Spokane NWS
For 2000 ft. to 4000 ft.
Tuesday Tuesday Night Wednesday
Weather: Rain/Snow Rain/Snow then snow showers Snow Showers
Temperatures: 36 deg. F. 25 deg. F. 26 and falling deg. F.
Wind Direction: South Southwest Southwest
Wind Speed: 10-15 14-16 6-9
Expected snowfall: 1 in. 1 in. 1 in.
For 4000 ft. to 6000 ft.
Tuesday Tuesday Night Wednesday
Weather: Heavy Snow Snow Snow Showers
Temperatures: 31 deg. F. 23 deg. F. 24 and falling deg. F.
Wind Direction: South Southwest Southwest
Wind Speed: 13-17 11-17 6-9
Expected snowfall: 7-11 in. 3-5 in. 1 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.