Loose Wet
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1–2
Air temperatures last night remained above freezing on the peaks due to inversion conditions. Below freezing air temperatures were mostly limited to locations on or just above the mountain valley floors. A decent but superficial snow surface refreeze is expected to have occurred last night despite above freezing air temperatures due to radiational cooling of the snowpack under clear skies. Snow surface melt is expected to occur faster today than yesterday with clear skies and air temperatures already above freezing at sunrise. Increasing SW winds may not start to appreciably slow snow surface melt until around late morning or midday.
The upper snowpack is not well established in melt-freeze and will be prone to wet loose avalanches today. Once more than a couple of inches of surface wet snow forms, wet loose avalanches that start small and then gain size with vertical run will be possible on all aspects. Avalanche size is expected at D1 to D2 depending on size of the slope. Terrain traps such as creek beds or cliffs could easily allow for burial or injury from what would otherwise be a size D1 avalanche.
Slope angle is the easy way to manage this avalanche problem as most wet loose avalanches will occur on slopes 35 degrees and steeper. Once surface wet snow develops, roller balls and pinwheels are indications that unstable conditions are present. Move to slopes less than 30 to 35 degrees in slope angle without steeper slopes above to minimize exposure to this avalanche problem.
(3/27/2021) Small wet loose avalanche triggered by ski cut on E aspect test slope at 7,700' at 11:30 am. Castle Peak, CA