Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1.5–2.5
A thick, well preserved layer of surface hoar (plus or minus a crust, depending on your aspect and elevation) is buried about 2' deep, and averaging slightly shallower in the West Mountains (1-1/2'). This problem has been highlighted on wind-loaded terrain mainly above 7,500' from the last cycle of natural and human-triggered avalanches. This layer formed during several days of dry weather and cool clear nights in early February and was quickly loaded and preserved with some snowfall. It appears to be responsible for a large portion of the recent avalanche activity in both zones & was likely the culprit in a remotely triggered slide. 2 feet deep is the ideal triggering depth: thin enough in many areas for a human to trigger, but thick enough to produce large and dangerous avalanches. We observed unstable test pit results at the crown of the aforementioned remotely-triggered slide yesterday.
The best way reduce your risk is by avoiding slopes over about 35 degrees, especially those that are of rocky, wind-affected, alpine nature. Pay attention to what's below you—look for trees, rocks, gullies, and other terrain traps. Good spacing like one at a time and regrouping in solid safe zones are easy insurance policies to take out if you choose to travel near avalanche terrain.
(3/3/2026)
Shallower burial depth of surface hoar from 2/14 in the West Mtns zone here on No Business Mountain. A pit on a north aspect reveals unstable test results on March 3rd.
Photo: George Halcom