THIS AVALANCHE ADVISORY EXPIRED ON March 4, 2020 @ 6:46 am
Avalanche Advisory published on March 3, 2020 @ 6:46 am
Issued by Kevin Davis - Idaho Panhandle Avalanche Center

Selkirks/Cabinets

bottom line

Yesterday in the Cabinets I found good sliding conditions but a little crusty on the southerly slopes.  Not much stability concerns on these slopes due to multiple crusts in the upper pack.  However, on Lunch Peak I found two very distinct layers of buried surface hoar on a north aspect.  Be careful on steep, convex terrain on NE - N - NW aspects.  The wind has cranked up too so watch for windslabs on these aspects too.  

How to read the advisory

Selkirks/Cabinets

How to read the advisory

Yesterday in the Cabinets I found good sliding conditions but a little crusty on the southerly slopes.  Not much stability concerns on these slopes due to multiple crusts in the upper pack.  However, on Lunch Peak I found two very distinct layers of buried surface hoar on a north aspect.  Be careful on steep, convex terrain on NE - N - NW aspects.  The wind has cranked up too so watch for windslabs on these aspects too.  

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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I think the thing that you're most likely to encounter tomorrow is windslabs.  The wind speeds went up yesterday out of the W/SW and this could have been transporting the existing surface snow to leeward faces and sculpting the westerly faces.  Last night we got an additional .4" of SWE which roughly translates to 3" of snow.  This new snow would have been loading most heavily on the easerly faces. It may be a little heavier snow so that might add to the weight of the slab over the upper surface hoar layer.  So watch for instability as you're climbing up to the ridgelines.  Be careful on and under cornices.

Avalanche Problem 2: Persistent Slab
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Two layers of buried surface hoar are present in the upper foot of the pack on northerly asepcts in the Cabinets.  We found this in the Selkirks last week but it was only one layer at that time.  Since then the other layer has formed and been buried so I think you'll find the same problem in both ranges now.  I had to hammer on the column to get them to go but they both failed cleanly and I could easily see the intact flakes.  I actually heard the lower one shear off, which I don't experience alot.  Sounded like fingernails on a chalkboard, creepy.  Ha, more like a sandpapery sound.  If you trigger one, you'll likely trigger the other and have twice as much snow moving.  If these exist under a windslab, now you have a real problem.  I would avoid steep, convex, unsupported, complex terrain on northerly aspects today.  Hammer on the low consequence features as you're moving to get an idea of how sensitive these layers are.  The pack on north asepcts is still cold so they will hang around for a while yet.

advisory discussion

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You'll find relatively decent sliding conditions out there today.  The best quality snow is in the trees on northerly aspects.  Its mostly crusty everywhere else.  We're about average for snow water content in the snowpack right now.  It feels like spring already and we need about a month more of winter to add to the pack.  We'll see but spring powder is some of my favorite, and then a good corn cycle right after that.  Not too much to ask for...

Weather and CURRENT CONDITIONS
weather summary 
Today, tonight, and Wednesday will be windy. Periods of light to
moderate snow will impact the mountain passes at times, but dry
weather is expected across Basin. The passage of a slow moving
frontal system Friday night and Saturday will produce our best
chance for widespread precipitation with a mix of rain and snow in
the lowlands and moderate snow for the mountains.
Weather observations from the Region
0600 temperature: 31 deg. F.
Max. temperature in the last 24 hours: 31 deg. F.
Average wind direction during the last 24 hours: W
Average wind speed during the last 24 hours: 5 mph
Maximum wind gust in the last 24 hours: 10 mph
New snowfall in the last 24 hours: 3 inches
Total snow depth: 132 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Spokane NWS
For 2000 ft. to 4000 ft.
Tuesday Tuesday Night Wednesday
Weather: A 10 percent chance of rain after 4pm. Snow level rising to 4300 feet in the afternoon. Mostly sunny. A chance of rain and snow before 1am, then a chance of rain between 1am and 4am, then a chance of rain and snow after 4am. Snow level 4000 feet lowering to 3400 feet after midnight . Mostly cloudy. Chance of precipitation is 30%. A chance of snow before 9am, then a chance of rain and snow between 9am and 10am, then a slight chance of rain after 10am. Mostly sunny. Chance of precipitation is 40%.
Temperatures: 46 deg. F. 33 deg. F. 42 deg. F.
Wind Direction: SW SW W
Wind Speed: 9-13 14-17mph, gusting 25 10-13
Expected snowfall: none in. none in. none in.
For 4000 ft. to 6000 ft.
Tuesday Tuesday Night Wednesday
Weather: A slight chance of snow between 10am and 4pm. Partly sunny. Breezy. Chance of precipitation is 20%. A 30 percent chance of snow, mainly after 4am. Mostly cloudy. Breezy. A 40 percent chance of snow, mainly before 10am. Mostly cloudy, then gradually becoming sunny. Wind chill values as low as -1. Windy.
Temperatures: 34 deg. F. 18 deg. F. 30 deg. F.
Wind Direction: W SW W
Wind Speed: 14-20mph, gusting 31 22mph, gusting 33 18-28mph, gusting 43
Expected snowfall: none in. <1/2 in. <1/2 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.