THIS AVALANCHE ADVISORY EXPIRED ON January 12, 2019 @ 6:27 am
Avalanche Advisory published on January 11, 2019 @ 6:27 am
Issued by Kevin Davis - Idaho Panhandle Avalanche Center

Selkirks/Cabinets
St. Regis Basin/Silver Valley

bottom line

This week was a good one for new snow accumulation.  Temperatures warmed on Wednesday and we saw rain and heavy snow to the mountaintops which created a wet layer on top yesterday.  The wet snow over the lighter snow will create some concerns as you gain elevation today since the wet snow layer will be freezing up high.  Triggering the wet stuff could release a weak layer in the light snow so be cautious around steeper terrain on any aspect.  

How to read the advisory

Selkirks/Cabinets
St. Regis Basin/Silver Valley

How to read the advisory

This week was a good one for new snow accumulation.  Temperatures warmed on Wednesday and we saw rain and heavy snow to the mountaintops which created a wet layer on top yesterday.  The wet snow over the lighter snow will create some concerns as you gain elevation today since the wet snow layer will be freezing up high.  Triggering the wet stuff could release a weak layer in the light snow so be cautious around steeper terrain on any aspect.  

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.

1. Low

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Below Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
    Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1: Wet Slab
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    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
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    Very Large
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The weather warmed up on Wednesday and the surface snow received rain and we picked up a few inches of heavy wet snow as well.  This 4-6 inch layer was sliding on the lighter snow underneath.  You could trigger this layer as you venture into 35 degree terrain on any aspect.  This layer will be freezing up and forming a solid crust as the cold weather continues but southerly aspects may soften on the steeps with direct sun.  Watch how this layer changes with time and elevation to know how to mitigate hazards today.

Avalanche Problem 2: Persistent Slab
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In the Selkirk Mountains just north of Flattop Mountain Eric and I found about 5 feet of snow on a NW aspect.  We dug down about 3 feet in the pack and found that the light snow we got this week is gaining density due to the weight of the new heavy snow.  That is good in that it is stabilizing weak layers from earlier this week - which I'm calling a persistent slab, but they are still there.  It would be possible to trigger these weak layers in steep terrain on northerly aspects today, particularly by triggering the wet slab which would get alot of weight moving.  

advisory discussion

Melissa is out of town this week so we are relying on observations from Silver Mountain for snowpack.  Thanks to Miles Rinne for keeping us informed.  Don't forget about the Doug Abromeit Avalanche Scholarship.  See our education page about winning a free avalanche course.  Send your essays to me at kevmodavis@gmail.com and not the email shown on that page, it's not working.

recent observations

In the Silver Valley yesterday, intel from Silver Mountain related cornice buildup.  Temps rose to above freezing yesterday afternoon but then dropped after 4PM.  You should have crusty conditions in the St. Regis Basin/Silver Valley today.  The crust is helping stability but not the sliding conditions.  It should form a pretty dense layer as it freezes up but watch the steeps in the direct sun this weekend as it may be enough radiation to warm and thus weaken any strength from ice formation.  Not oo concerned with the surface hoar weak layer nor the basal facets as they have healed with time in most places.  You may find them at high elevation in areas of shallow snowpack around rocks.

Weather and CURRENT CONDITIONS
weather summary

Looks like the weather across our forecast region will be partly to mostly sunny today and for the near future.  Can you handle that?  Day time temperatures will approach the freezing mark but night time temps will drop back into the 20s.  That will make for an intersting crust layer at the top.  Yes, I'm thinking of all that good powder underneath it too...  Just remember those weak layers in the light snow and give them a chance to strengthen, they will.  Also, steep southerly aspects receiving direct sun could soften so be aware that could weaken layers.

Weather observations from the Region
0600 temperature: 28 deg. F.
Max. temperature in the last 24 hours: 33 deg. F.
Average wind direction during the last 24 hours: NNW
Average wind speed during the last 24 hours: calm mph
Maximum wind gust in the last 24 hours: 5 mph
New snowfall in the last 24 hours: trace inches
Total snow depth: 60 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Spokane NWS
For 2000 ft. to 4000 ft.
Friday Friday Night Saturday
Weather: Fog then Partly sunny mostly clear Fog then Partly sunny
Temperatures: upper 30s deg. F. 20s deg. F. upper 30s deg. F.
Wind Direction: NE NE NE
Wind Speed: light light light
Expected snowfall: none in. none in. none in.
For 4000 ft. to 6000 ft.
Friday Friday Night Saturday
Weather: Partly sunny clear Mostly sunny
Temperatures: mid 30s deg. F. 20s deg. F. mid 30s deg. F.
Wind Direction: E S E
Wind Speed: light light light
Expected snowfall: none in. none in. none 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.