THIS AVALANCHE ADVISORY EXPIRED ON January 5, 2019 @ 5:13 am
Avalanche Advisory published on January 4, 2019 @ 5:13 am
Issued by Melissa Hendrickson - Idaho Panhandle Avalanche Center

St. Regis Basin/Silver Valley

bottom line

With just enough snow and wind yesterday, wind slabs will be our main concern today and through the weekend.  Pay attention to our traditional start zones on the N-NE-E aspects as they will be sensitive. Also, our couple of problem layers keep getting buried a little deeper each storm, but it is important to keep those in mind as we get further into the new year.  Pay attention to your terrain choices and watch for signs of instability.

How to read the advisory

St. Regis Basin/Silver Valley

How to read the advisory

With just enough snow and wind yesterday, wind slabs will be our main concern today and through the weekend.  Pay attention to our traditional start zones on the N-NE-E aspects as they will be sensitive. Also, our couple of problem layers keep getting buried a little deeper each storm, but it is important to keep those in mind as we get further into the new year.  Pay attention to your terrain choices and watch for signs of instability.

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: Wind Slab
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Winds on Thursday and Thursday night generally trended from the southwest which formed slabs on leeward terrain.  We observed wind slab formation while we were out on Thursday that were very sensitive to human triggers.  Give starting zones and typical wind loaded areas a wide berth this weekend.  More snow and wind is supposed to enter our area on Saturday, which will make the wind slab problem persist throgh the weekend.  

Avalanche Problem 2: Persistent Slab
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Buried surface hoar from back around Thanksgiving as well as an ice crust from last week are still lurking in the snowpack.  While these are becoming less and less reactive in stability tests, they are still down there in many locations.  Assess the snowpack you plan on riding and sliding as the location and reactivity vary spatially. 

Avalanche Problem 3: Deep Slab
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We started out the winter with a weak base due to cold temperatures and that structure is still there, but patchy and variable as to where you'll find it.  Areas of shallow snowpack and smooth terrain features like bedrock faces and beargrass fields are the likely places for it to exist.  Triggering this layer is not easy since it is at the bottom of the pack and getting buried deeper, but if it does it will be big.  Extra caution in areas with shallow snowpacks.  

recent observations

We toured to the FAA ridge yesterday above Lookout Pass and found reactive windslabs on the N-NE-E ridgelines that were very susceptible to human triggers.  Give these areas of loading a wide berth this weekend as there will be little time to stabilize between storms.  On Wednesday we were still getting the previous storms wind slabs and crossloading areas to trigger as well, so there is a further layering affect in some areas.  Touring this week at multiple locations across the Silver Valley, the buried persistent layers are still hanging out.  On the western side of our advisory area they seem to be a bit more prevalent, including a rain crust and weak snow from the last storm that the eastern side seems to have missed out on.  Today, as we were leaving Lookout Pass, we hit the rain line at about 3800'.  

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/Snow Mostly Cloudy Mostly Cloudy then Chance Rain/Snow
Temperatures: 36 deg. F. 28 deg. F. 37 deg. F.
Wind Direction: S E E
Wind Speed: 8-11, G21 6 3-6
Expected snowfall: <1" in. 0 in. <.5" in.
For 4000 ft. to 6000 ft.
Friday Friday Night Saturday
Weather: Snowy and Breezy Slight Chance Snow then Mostly Cloudy Chance Snow
Temperatures: 30 deg. F. 21 deg. F. 29 deg. F.
Wind Direction: SW S SE
Wind Speed: 17-22, G39 9-17, G26 10-13
Expected snowfall: 1-3 in. <.5 in. <.5 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.