Avalanche Advisory published on January 15, 2019 @ 6:27 am
This Avalanche Advisory expires in 1 hours, 55 minutes
This advisory is valid for 24 hours
Issued by Melissa Hendrickson - Idaho Panhandle Avalanche Center

St. Regis Basin/Silver Valley

bottom line

Warm temperatures the past several days have helped the snowpack stabilize. Still of concern is the November buried surface hoar layer where we have areas of thin snowpack at the highest elevations and around rock outcrops.  Weather patterns will be changing Thursday, but until then enjoy the stability and the visibility.

How to read the advisory

St. Regis Basin/Silver Valley

How to read the advisory

Warm temperatures the past several days have helped the snowpack stabilize. Still of concern is the November buried surface hoar layer where we have areas of thin snowpack at the highest elevations and around rock outcrops.  Weather patterns will be changing Thursday, but until then enjoy the stability and the visibility.

2. Moderate

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

1. Low

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Near Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

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

Broken record alert; we've been talking about the persistent slab problem since we started forecasting this season.  The posiblility of triggering this is decreasing and unlikely, but it is still present in our snowpack.   Yesterday in the Silver sidecountry we found the November buried surface hoar more than a meter down, but there are still 5mm facets lurking down there.  This could still be a concern on steep, convex slopes with variable snow depths.  Choose your routes wisely and avoid these areas.  We still have thin snowpack in many locations.  

recent observations

Yesterday in the sidecountry around Silver Mountain we found crusts on all aspects.  A strong inversion had the high elevations baking at 40oF and the middle elevations had surface hoar formation in the cooler temperatures.  Between the rain crusts from last week and the sun crusts, there are a lot of smooth sliding surfaces that have the potential to get buried as the next system rolls in on Thursday.  These layers were not being reactive for us yesterday, but might change when more weight gets added to them.  I expect more surface hoar to have grown at the higher elevation last night as it was another clear one and the temperatures started falling back below freezing.  The buried surface hoar from November was too deep in the areas we checked to be reactive in tests, but the facets were still visible with the naked eye, up to 5mm big. They are continuing to round and bond, but still a concern where there isn't a significant pack above them.  Yesterday we found the snowpack to be in the 150 cm range where we were digging. 

Thursday the weather is going to change, so Friday's forecast will be a different story. Until then, enjoy the stability and the vitamin D.  And thank you everyone who sent in observations this week.  

Weather and CURRENT CONDITIONS
Two-Day Mountain Weather Forecast Produced in partnership with the Spokane NWS
For 2000 ft. to 4000 ft.
Tuesday Tuesday Night Wednesday
Weather: Mostly Sunny Mostly Cloudy Slight Chance of Snow
Temperatures: 35 deg. F. 26 deg. F. 34 deg. F.
Wind Direction: E E E
Wind Speed: 5 Light Light
Expected snowfall: 0 in. 0 in. 0 in.
For 4000 ft. to 6000 ft.
Tuesday Tuesday Night Wednesday
Weather: Mostly Sunny Mostly Cloudy Slight Chance of Snow
Temperatures: 28 deg. F. 21 deg. F. 30 deg. F.
Wind Direction: E SE E
Wind Speed: 10 10 10-14
Expected snowfall: O in. O in. O 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.

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