Persistent Slabs
- Hochgebirge
- Waldgrenze
- Unterhalb der Waldgrenze
- Wahrscheinlichkeit
- Possible
- Größe
- 2
Any slope harboring old snow that fell in October should be avoided because it will likely produce an avalanche. The old October snow became weak and faceted. It is now a persistent weak layer on which many avalanches have occurred. Yesterday this layer was collapsing and whumpfing as Trent and I skied in Big Cottonwood Canyon. I think similar conditions exist in the Provo area mountains.
With 4-6 inches of heavy, new snow this morning, this layer will likely produce avalanches today if you get on a slope steeper than 30 degrees.
HEADS UP - More snow and increased S/SW winds will come this afternoon. These southerly winds will drift snow onto northerly facing slopes which are ones with the weakest and most unstable snow. Depending on how much snow falls tonight, avalanches could occur naturally tomorrow. I would also expect that you could trigger them remotely which means you can trigger them from some distance away.
Below is a photo of the snowpack at 8,500' on a north facing slope in the Provo area mountains, with the facets at the bottom. The weak facet layer depth will increase with elevation.