THIS AVALANCHE ADVISORY EXPIRED ON January 3, 2018 @ 7:00 am
Avalanche Advisory published on January 2, 2018 @ 7:00 am
Issued by Melissa Hendrickson - Idaho Panhandle Avalanche Center

St. Regis Basin/Silver Valley

bottom line

The snowpack went through the ringer over the holiday weekend, recieving up to 2ft+ of snow and then some rain/mixed precipitation on top of that.  Even though the snowpack is starting to heal and get stronger, there are multiple persistent weak layers that can be triggered causing an avalanche.  Be conservatice in your decision making and route finding, dangerous avalanche conditions still exist but are slowly strengthening. 

How to read the advisory

St. Regis Basin/Silver Valley

How to read the advisory

The snowpack went through the ringer over the holiday weekend, recieving up to 2ft+ of snow and then some rain/mixed precipitation on top of that.  Even though the snowpack is starting to heal and get stronger, there are multiple persistent weak layers that can be triggered causing an avalanche.  Be conservatice in your decision making and route finding, dangerous avalanche conditions still exist but are slowly strengthening. 

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.

2. Moderate

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Below Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
    Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
Avalanche Problem 1: Wind Slab
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Ridges and mountain tops still have signs of wind transportation with some very firm wind slabs which are now covered by a fresh layer of storm slab and surface hoar.   

Avalanche Problem 2: Storm Slab
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The storm slabs are strengthening but at a slower rate due to the cold temperatures. Parts of the region recieved rain from the 12/29 - 12/30 storm, so there is a rain crust mixed in with the storm slabs.  Most of the region recieved a 2 to 4 cm rain crust from about 4500 - 5300', which transitions to a softer storm slab at the higher elevations. 

Avalanche Problem 3: Persistent Slab
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There is a buried surface layer in many areas still from the Thanksgiving storm. It is proving to be stubborn and strengthening, but still reactive in some pit tests across the region.  This is now buried down under over a 100cm of snow in most locations. 

recent observations

Gabe White traveled to the FAA tower area yesterday across from Lookout Pass and reported quite good skiing above 5500'.  Stability tests showed that the storm layer was failing with easy force, but not propegating across the column. His pit tests did also have one failure of the Thanksgiving crust, at 28 taps, but no propegation.  He also saw extensive evidence of wind slabs in the higher terrain. 

North Idaho College Outdoor Pursuits reported observations from the Lone Lake area yesterday. They also had failures at 27 taps, but no propegation from the Thanksgiving crust.  They dug in the rain crust location, and had failures on the new storm as well, but no propegation.  

There was one report of a human triggered avalanche over the weekend in the St. Regis Basin area.  Evidence of naturals were reported in the Stevens and Lone Lake areas. 

All locations reported extensive surface hoar formation from the cool, clear nights we've had over the New Year Holiday. Something to keep in mind when our next system comes in.  I'm not really a big fan of Groundhog's Day....

Weather and CURRENT CONDITIONS
Weather observations from the Region
0600 temperature: 20 deg. F.
Max. temperature in the last 24 hours: 23 deg. F.
Average wind direction during the last 24 hours: 6
Average wind speed during the last 24 hours: NE mph
Maximum wind gust in the last 24 hours: 8 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 49 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Spokane NWS
For 2000 ft. to 4000 ft.
Tuesday Tuesday Night Wednesday
Weather: Cloudy Cloudy then slight chance of snow Slight chance snow then cloudy
Temperatures: 29 deg. F. 24 deg. F. 32 deg. F.
Wind Direction: NE NE NE
Wind Speed: 6-8 8 6
Expected snowfall: 0 in. 0 in. 0 in.
For 4000 ft. to 6000 ft.
Tuesday Tuesday Night Wednesday
Weather: Increasing clouds mostly cloudy slight chance snow
Temperatures: 31 deg. F. 27 deg. F. 38 deg. F.
Wind Direction: S S S
Wind Speed: 7 8 6
Expected snowfall: 0 in. 0 in. 0 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.