THIS AVALANCHE ADVISORY EXPIRED ON February 17, 2018 @ 6:59 am
Avalanche Advisory published on February 16, 2018 @ 6:59 am
Issued by Melissa Hendrickson - Idaho Panhandle Avalanche Center

St. Regis Basin/Silver Valley

bottom line

The weekend is about to roll in with a bang weather wise.  Going into Friday morning with an overall fairly stable snowpack, but the snow accumulation is going to ramp up throughout the day today and not stop until Sunday night.  Storm totals could exceed 4 feet in areas and will be accompanied by strong winds.  Expect the avalanche danger to increase throughout Saturday and Sunday.  Significant snowfall and strong winds are two of the avalanche red flags. 

How to read the advisory

St. Regis Basin/Silver Valley

How to read the advisory

The weekend is about to roll in with a bang weather wise.  Going into Friday morning with an overall fairly stable snowpack, but the snow accumulation is going to ramp up throughout the day today and not stop until Sunday night.  Storm totals could exceed 4 feet in areas and will be accompanied by strong winds.  Expect the avalanche danger to increase throughout Saturday and Sunday.  Significant snowfall and strong winds are two of the avalanche red flags. 

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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The current storm system has both the snow avaliable to transport and the wind speeds to make that happen.  Watch for changing conditions throughout the day, as it will take very little time for new windslabs to form. 

Avalanche Problem 2: Storm Slab
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There is 5 - 8 " of loose dry snow overlying last weeks smooth sliding surface.  This loose snow is breaking easily and creating small loose slides in steep terrain. In other locations this new snow is starting to form a slab. The danger due to storm slabs will be increasing throughout the advisory period as we recieve more snow loading.

Avalanche Problem 3: Persistent Slab
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Still mentioning this lurking hidden beast. Found evidence of rounding facets on a thin south facing snowpack yesterday. None of the burried weak layers are very reactive in pit tests, but they are still capable of producing avalanches. Shallow trigger points are places you could initiate an avalanche on one of those layers.  Dig down in your location, it's the only way you are going to know if they are there and reactive. 

recent observations

Traveled to the sidecountry of Silver yesterday and found stable conditions going into this storm cycle, with a small storm slab overlying the crust from last week.  Unfotunately this crust will provide a pretty good sliding surface for the new snow that is coming in.  We also observed suface hoar above 5500' which will be something to pay attention to if it gets buried intact.

 

Weather and CURRENT CONDITIONS
Weather observations from the Region
0600 temperature: 18 deg. F.
Max. temperature in the last 24 hours: 20 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 11 mph
Maximum wind gust in the last 24 hours: 26 mph
New snowfall in the last 24 hours: 1 inches
Total snow depth: 64 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 and Breezy Snow Likely then Chance Snow Heavy Snow and Patchy Blowing Snow
Temperatures: 33 deg. F. 27 deg. F. 31 deg. F.
Wind Direction: SW W S
Wind Speed: 9-14 then 16-21 5-9 7-12 then 17 -22
Expected snowfall: 3-5 in. 1-3 in. 8-12 in.
For 4000 ft. to 6000 ft.
Friday Friday Night Saturday
Weather: Heavy Snow and Windy Heavy Snow and Breezy then chance snow Heavy snow and patchy blowing snow
Temperatures: 25 deg. F. 22 deg. F. 28 deg. F.
Wind Direction: W W SW
Wind Speed: 18-30 G45 10-18 11-18 G29
Expected snowfall: 5-9 in. 3-5 in. 11-17 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.