Last night's new snow and wind created reactive wind slabs along ridge crests. Ski cuts produced shooting cracks and one small wind slab release. Newer weak layers that were buried since 1/27 are concerning, especially on SE, but lack a slab at present. I did not find any other concerning weak layers in the top 1m of the snowpack.
Skies threatened to clear this morning but remained broken all day. Cloud cover finally began decreasing in the late afternoon. Ridge-level winds were generally light to moderate but gusty. There were small amounts of snow moving - most had already been stripped by W and NW winds.
My objective was to do an inventory of near surface/newer weak layers and look for the 1/5 SH. Below the 1/27 interface, the snowpack looked quite good in the three snowpits I dug. I did not find any noteworthy weak layers or get any ECTPs below the 1/27 interface. The 1/27 - 2/5 weak layers look concerning, especially on SE, but there is not enough load to be a widespread issue.
@8200', NE: Sheltered small opening surrounded by trees. HS 190cm. 1/27 consisted of weak FC down 30cm. The bottom ~7cm of the "slab" was 4F- (1/27 storm?) but the rest was F - ECTN15,18. No visible layering and ECTX below 1/27.
@8750', SE, 31*: Sheltered opening in sparse trees. HS 170. I found 21cm of F snowfall (since 2/5?) sitting atop a stout 2cm thick MFcr. Below that was by far the weakest FC I saw today. ECTP1,2 below the crust. There was just this single crust in the upper snowpack. A few other layers were visible in the top 1m but produced ECTXs. Despited the very poor results, there wasn't enough slab here to be an issue. The crust was acting as the slab in the test, which I don't think translates to the slope scale. Similar to other obs from ~SE aspects, this would react poorly when loaded.
@8650', N: Small exposed slope. HS averaged 200 but varied due to boulder ground cover. No distinct weak layers in the top 1m. This slope may have been affected by the late-Jan N wind event which may have destroyed any surface faceting. Indistinct ECTNs in the top 40cm. The block sheared 75cm down when tipped out of the put - I *might* have seen some SH shards but the layer was not visible in the pit wall.
Both of the last two pits were adjacent to other pits I dug on 1/21. On that day, both pits produced ECTPs on 1/5 so the lack of results today seems to bode well.
Problem | Location | Distribution | Sensitivity | Size | Comments |
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Layer Depth/Date: 30-50cm Comments: Rose shaded where observed. Ski cuts produced shooting cracks and one small wind slab release. The wind slabs appeared to be failing on the old/new interface rather than a PWL. |
I observed a "budding" persistent slab problem involving 1/27-2/5 weak layers, but there is not enough slab at present to be an issue.