Quick report
- Red Flags
- Recent Avalanches, Wind Loading, Cracking, Poor Snowpack Structure
In my field work and observations from others, I'm seeing the PWL slowly strengthening, especially in areas with a deeper (> 120 cms) snowpack. Lots of probing in the snowpack today with a shallow snowpack up to 8,500'. On a northwest aspect at 9,400' with 130 cm deep snowpack, we found a strong 1F slab 100 cm deep on top of 4F-hard facets with ECTX (no collapse of the weak layer).
We are entering a tricky period as we're getting fewer collapses and seeing the PWL gaining strength. My current concerns with the PWL are in thinner snowpack areas, and this can occur in three scenarios:
1. Mid-elevations where there is simply less snow.
2. Steep, rocky areas in mid and upper elevations where the snowpack is generally thinner.
3. "Repeater" slopes at the mid and upper elevations where the slope has avalanched and has been partially filled in from recent storm snow and wind-drifted snow.
It is possible you can trigger an avalanche in these types of areas with a thinner snowpack where the avalanche propagates to areas on the slope where the snowpack is deeper.
I continue to travel cautiously on mid and upper-elevation slopes facing W/N/E.
Photo of N/NE winds on Thursday morning over Mineral Fork (photo Mark Johnston)
Wind sculpted ridgeline above the east face of Mt. Raymond, including a natural avalanche that had been reported earlier this week.
Snowpack
- Instability Comment
- <p>Overall, the PWL is slowly gaining strength and in areas with a snowpack deeper than about 120 cms (4'), the facets in the bottom ~30 cms of the snowpack continue to gain strength and are now 4F hard. Recent winds, increasing winds forecast for later Friday, and snowfall this weekend will overload the PWL in some areas.</p> <p>Fresh wind drifts along exposed ridges and slopes above about 9,000' with cracking. The biggest issue is where the fresh wind drifts have formed on top of the PWL.</p>
Some fresh wind drifts up to 15 cms (6" thick) on mostly west-facing aspects above 9,000'
The snow surface is weakening due to the past few days of cold, clear weather and the current snow surface may be a weak layer with additional wind and snow expected later Friday.