THIS AVALANCHE ADVISORY EXPIRED ON February 29, 2020 @ 6:19 am
Avalanche Advisory published on February 28, 2020 @ 6:19 am
Issued by Melissa Hendrickson - Idaho Panhandle Avalanche Center

St. Regis Basin/Silver Valley

bottom line

As the temperature rises today, the snowpack will become more unstable. Look for rollerballs as an indicator that it has wamed up and to stay out of avalanche terrain. We still have a lurking buried persistent weak layer on our cooler, sheltered aspects. Dig down to assess the location where you are in to see if it is there. 

How to read the advisory

St. Regis Basin/Silver Valley

How to read the advisory

As the temperature rises today, the snowpack will become more unstable. Look for rollerballs as an indicator that it has wamed up and to stay out of avalanche terrain. We still have a lurking buried persistent weak layer on our cooler, sheltered aspects. Dig down to assess the location where you are in to see if it is there. 

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.

2. Moderate

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Below Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
    Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1: Loose Wet
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Pinwheels, rollerballs, tree bombs, punchy snow; they are all signs that the temperature is starting to rise and that the avalanche danger is going up with it. It will be very likely to trigger a loose wet slide on steeper terrain, especially on the sunny exposures, as the snowpack gets more saturated. These slides can have enough power to knock you over and take you for a ride, picking up more snow as they travel downhill.  High consequence areas such as gullies or cliffs won't make that ride very enjoyable.  If you are seeing road cuts that look like the picture below, stay out of avalanche terrain!  Avoid this problem by starting early, and getting out before the sun really heats things up. 

Avalanche Problem 2: Persistent Slab
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Background history: We had lots of sunny, clear days last week which led us to having very large surface hoar, in some locations up to 3cm! Sunday and Monday a winter storm rolled through, dropping up to a foot at our higher elevations.  In some locations the surface hoar got knocked down by the winds or the sun, but in the more shaded and sheltered areas it got buried whole.  This was still reactive in pit tests.  Sheltered is the key word here.  You might dig a pit near the top of the ridge where the surface hoar was destroyed by the wind, only to drop down the slope 100ft to find it alive and active under the snowpack.  Assess your locations well for this hidden dragon.  

Avalanche Problem 3: Cornice
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The majority of the large cornices are on the N-E aspects, but we have some smaller ones on the other aspects from our northern storms. Give these a wide berth as the temperatures heat up, they tend to break off further back than you think. 

recent observations
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Yesterday we travelled to the Gold Hill and Moon Pass area. North aspects were holding powder very well, we'll see how they do in the warm temperatures today. In our location it was fairly easy to find the buried surface hoar: find a north facing sheltered aspect and dig down a foot.  Pit tests were reactive enough to make me leary of the steeps.  On the west side of the forecast zone it is much harder to find, but there were reports of naturals on it earlier in the week on the east side of the zone.  Check your location by digging down!  We will see how it fairs through today's warm spell. I expect it to get more reactive before it gets better.  

As the day progressed yesterday, it was very easy to trigger wet slides on the sun exposures.  This will happen much earlier in the day today and on all aspects if the temperature increases like it is supposed to.  Saturday will be cold again, so that should lock the pack back up. Check out the video below for some of the wet instabilities from today.  

 

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: Mostly Sunny Chance Rain then Chance Rain/Snow Snow Showers likely
Temperatures: 52 deg. F. 31 deg. F. 37 deg. F.
Wind Direction: E S SW
Wind Speed: 7 9-16, G25 14-17, G25
Expected snowfall: 0 in. <.5 in. <.5 in.
For 4000 ft. to 6000 ft.
Friday Friday Night Saturday
Weather: Mostly Sunny Snow Likely Snow showers
Temperatures: 39 deg. F. 22 deg. F. 25 deg. F.
Wind Direction: SW SW SW
Wind Speed: 10-13 14-17, G26 15-17, G26
Expected snowfall: 0 in. 1-2 in. 1-3 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.