THIS AVALANCHE ADVISORY EXPIRED ON February 1, 2020 @ 6:29 am
Avalanche Advisory published on January 31, 2020 @ 6:29 am
Issued by Melissa Hendrickson - Idaho Panhandle Avalanche Center

St. Regis Basin/Silver Valley

bottom line

The snowpack does not not like rapid changes, especially a rapid increase in weight piled on top of buried weak layers. We are getting a rapid increase in weight due to rain, and then snow and wind on top of several buried weak layers. Natural avalanches may be possible and human triggered avalanches are likely on Friday and Saturday. 

How to read the advisory

St. Regis Basin/Silver Valley

How to read the advisory

The snowpack does not not like rapid changes, especially a rapid increase in weight piled on top of buried weak layers. We are getting a rapid increase in weight due to rain, and then snow and wind on top of several buried weak layers. Natural avalanches may be possible and human triggered avalanches are likely on Friday and Saturday. 

3. Considerable

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

3. Considerable

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

3. Considerable

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Below Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
    Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
Avalanche Problem 1: Wet Slab
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With the snow line up over 7000ft today, which is higher than our tallest peaks, expect to see rain at the highest elevations. Up to an inch of rain is predicted which will destabilize the top layers of our snowpack quickly. Indicators that wet avalanches are likely include large roller balls or pinwheels, point releases of wet loose snow on steeper slopes, and sinking deeper than your boot top into wet snow. If these are happeneing, it's time to steer clear of avalanche terrain. 

The wet slab problem has the potential to turn to a storm slab problem on Saturday when the rain line lowers and we switch back to snow of the solid form.  The snowpack is complicated right now and the weather is complicated, two reasons to use extra caution. 

Avalanche Problem 2: Persistent Slab
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Depending on the elevation, there are several buried persistent weak layers in the snowpack that have the potential to be woken up by the new weight.  A much smaller avalanche in the top layers has the potential to step down through the pack and these persistent weak layers creating a much bigger avalanche with larger consequences. Everyone should assess the snowpack in their location to see what kind of persistent weak layers you are dealing with.  

Avalanche Problem 3: Loose Wet
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With all the rain it will turn the snowpack into a hot mess by Friday afternoon. Expect to see loose wet slides up to the highest elevations. These slides are often slow and harmless, but they can knock you over and run you into a cliff or a tree in a hurry.  

Whatever you do, don't do what these people did in this video!

 

recent observations
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Yesterday we toured at Sunset Peak where we found a complicated snowpack.  There were several buried persistent weak layers on all aspects that have formed from the weather we've had this past week. Yesterday they were reactive in pit tests but not propegating. I'm expecting these to be problematic with the additional loading of today's rain. These layers weren't visible from our surface observations yesterday, the only way we knew that they were there was to dig down.  Due to all the variables and uncertainty in the mountains right now, we are making very conservative decisions.  

Another note to consider as we work our way into the weekend is wind slabs. I didn't list them as a problem for today, Friday, as the new precipitation is coming in as rain and the lingering slabs we found yesterday were very stubborn.  But expect wind slabs to be full on for Saturday when the precipitation turns back to snow and winds in the 40s.  The fastest way to load snow onto a slope is through windloading.  Expect wind slabs to develop throughout the day on Saturday and be sensitive to human triggering, especially with a very destabilized snowpack underneath from the rain.  

And if I haven't made it clear enough that the snowpack right now is a set of complicated layers with a lot of uncertainty, here is a video illustrating it more!  Stay safe this weekend and thank you everyone for all the observations you've been sending in, they are very helpful!

 

Weather and CURRENT CONDITIONS
Two-Day Mountain Weather Forecast Produced in partnership with the Spokane NWS
For 2000 ft. to 4000 ft.
Friday Friday Night Saturday
Weather: rain Mostly cloudy then chance rain rain
Temperatures: 44 deg. F. 39 deg. F. 46 deg. F.
Wind Direction: S S SW
Wind Speed: 7-10 9-11 13-15, G23
Expected snowfall: 0 in. 0 in. 0 in.
For 4000 ft. to 6000 ft.
Friday Friday Night Saturday
Weather: Breezy, Rain/snow then rain Breezy. Slight chance rain/snow then chance snow Snow and windy
Temperatures: 35 deg. F. 35 deg. F. 36 deg. F.
Wind Direction: SW SW SW
Wind Speed: 17-21, G34 23, G37 22-28, G44
Expected snowfall: 4-8 in. <.5 in. 3-7 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.