THIS AVALANCHE ADVISORY EXPIRED ON March 3, 2018 @ 6:53 am
Avalanche Advisory published on March 2, 2018 @ 6:53 am
Issued by Melissa Hendrickson - Idaho Panhandle Avalanche Center

St. Regis Basin/Silver Valley

bottom line

A series of small storms has been tracking across the Silver Valley, depositing a few inches yesterday and last night.  The smaller amounts in these storms accompanied by steady moderate temperatures have allowed these layers to bond, but have provided new fuel for windloading each day.  Expect windslab formation at the ridgelines. 

How to read the advisory

St. Regis Basin/Silver Valley

How to read the advisory

A series of small storms has been tracking across the Silver Valley, depositing a few inches yesterday and last night.  The smaller amounts in these storms accompanied by steady moderate temperatures have allowed these layers to bond, but have provided new fuel for windloading each day.  Expect windslab formation at the ridgelines. 

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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Variable wind directions have formed windslabs on multiple aspects.  Look for rounded pillows of snow or unusual snow surface to identify areas where wind has deposited snow.  

Avalanche Problem 2: Persistent Slab
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We've been basking in the glory of all the new snow the past two weeks, but remember that rain crust?  There are still facets down there sitting on top of that crust layer. The only way to know if they are present at the location you want to ride or slide is to dig down.  You'll know when you've dug far enough; all of a sudden it becomes much harder to shovel. It's getting harder to trigger this layer, but the consequences of triggering are becoming larger with each storm. Smart terrain management is required as this problem is most likely found in steep, open terrain, convex rolls, or thin spots within the snowpack. 

recent observations

We toured to West Willow yesterday and were surprised at the locations of the windslabs.  Looking back on the regional weather data, the winds have been squirrelly at the ridges, so check for windslabs this weekend in places you might not expect them. Our snowpack is looking really solid right now, on the Northern aspects we were seeing around 120 inches and the Southern aspects had around 80inches at 6000ft in elevation.  The rain crust that has been buried by over 2 weeks of amazing powder is still harboring facets above it.  We had this persistent weak layer react in one pit test location, but not the other ones.  It's really important that you assess each location by digging down to see if that layer is present and reactive.  Yesterday, at the lower elevations, we found that by afternoon, the potential for wet slides had increased and we were seeing roller balls forming.  Keep that in mind as you travel down from your favorite play areas.  

Weather and CURRENT CONDITIONS
Weather observations from the Region
0600 temperature: 25 deg. F.
Max. temperature in the last 24 hours: 27 deg. F.
Average wind direction during the last 24 hours: SE
Average wind speed during the last 24 hours: 9 mph
Maximum wind gust in the last 24 hours: 21 mph
New snowfall in the last 24 hours: 3 inches
Total snow depth: 85 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Spokane NWS
For 2000 ft. to 4000 ft.
Friday Friday Night Saturday
Weather: Snow Chance Snow then mostly cloudy Partly Sunny
Temperatures: 31 deg. F. 26 deg. F. 36 deg. F.
Wind Direction: SW SE E
Wind Speed: 8-11 7 5-7
Expected snowfall: 1-3 in. <.5 in. 0 in.
For 4000 ft. to 6000 ft.
Friday Friday Night Saturday
Weather: Snow Chance Snow then slight chance snow Chance snow
Temperatures: 26 deg. F. 18 deg. F. 27 deg. F.
Wind Direction: SW SW SW
Wind Speed: 10-14 8-11 5-7
Expected snowfall: 1-3 in. <1 in. <1 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.