THIS AVALANCHE ADVISORY EXPIRED ON February 3, 2018 @ 6:22 am
Avalanche Advisory published on February 2, 2018 @ 6:22 am
Issued by Melissa Hendrickson - Idaho Panhandle Avalanche Center

St. Regis Basin/Silver Valley

bottom line

It's Groundhog's Day and we are still caught in a time loop of the same three avalanche problems.  Storm slabs, windslabs, and persistent slabs. Expect avalanche danger to increase as we get more snow loading during the day on Friday accompanied by gusty winds and then changing to higher density snow/rain on Friday night.  Assess the terrain at each location by digging down into the snow to identify the layers at your location. Use cautious route-finding and conservative decision-making choices.  

How to read the advisory

St. Regis Basin/Silver Valley

How to read the advisory

It's Groundhog's Day and we are still caught in a time loop of the same three avalanche problems.  Storm slabs, windslabs, and persistent slabs. Expect avalanche danger to increase as we get more snow loading during the day on Friday accompanied by gusty winds and then changing to higher density snow/rain on Friday night.  Assess the terrain at each location by digging down into the snow to identify the layers at your location. Use cautious route-finding and conservative decision-making choices.  

3. Considerable

?

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

2. Moderate

?

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

1. Low

?

Below Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
    Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
Avalanche Problem 1: Wind Slab
  • Type ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

New snow fell overnight accompanied by gusty winds, as well as more snow and winds throughout the day Friday will lead to extensive windslab development in the upper elevations. 

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

Storm systems keep rolling through the region, depositing fresh snow at variable densities and temperatures. The frequency of the storms lends to lingering weaknesses between layers that have yet to fully bond and strengthen. Snow throughout Friday will add another layer of storm snow. 

Avalanche Problem 3: Persistent Slab
  • Type ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

The snowpack is gaining strength but still harbors buried weak layers.  The only way to assess these layers is to dig down into the snow at each location you plan on riding or sliding.  

recent observations

Visited Mullan Pass on Thursday and overall we were finding a right side up snowpack that is gaining strength on all aspects. We were still finding that the storm slabs were sensitive in pit tests (here).  We were also able to get a failure on one of the buried surface hoar layers on the north aspect today.  Expect these layers to be more reactive in shallower areas or around trigger points.  Generally speaking our region is doing well with depth of snowpack, we've reached 100% average snow water equivalent.  In our location today, there was a difference of a 100cm of snow from the north side to the south side on the same ridge!

 

 

Weather and CURRENT CONDITIONS
weather summary

We are hitting another round of Coeur d'Alene Mountain range precipitation roulette. Expect snow on Friday in the AM, then changing over to rain and snow in the PM over most of the forecast region. Gusty W-SW winds will also accompany the storm.  Friday night expect rain, with the snow level starting at 5600' and dropping to 5200' and mostly liquid precipitation in that time period elsewhere. Saturday is snow likely with more gusty winds from the W-SW. Expect the avlanche danger to stay elevated through the weekend with the heavy loading on the pack. 

Weather observations from the Region
0600 temperature: 29 deg. F.
Max. temperature in the last 24 hours: 29 deg. F.
Average wind direction during the last 24 hours: WSW-SW
Average wind speed during the last 24 hours: 8 mph
Maximum wind gust in the last 24 hours: 22 mph
New snowfall in the last 24 hours: 4-7 inches
Total snow depth: 64 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.