Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1–2.5
This zone has persistent weak layers buried 2-3 feet deep on most middle and upper-elevation slopes. There's no magical formula, but the most important factor we have on our side is time. It's been two days since the snowpack has been significantly stressed by new snow, wind, or major temperature fluxes. Imagine how you'd feel after two days on the beach with no email, no texts, and no news: probably pretty good, but you'd want more time there. Having more time is good for both you and the snowpack—but this problem is still very much present. Avalanches are being reported daily on this interface and most of these show wide propagation across slopes and terrain features. More snowfall overnight tonight and into Thursday will test these layers. Persistent slab avalanches are unpredictable on the best of days. If you find one of the land mines out there—and believe me, they exist—the MODERATE danger rating will mean little to you. Given the uncertainty surrounding these weak layers, skiing or riding in "prime-time", consequential avalanche terrain mean accepting this unknown and the risk associated with it.
ADDITIONAL DISCUSSION
The Wyoming Range continues to have a thin and tricky snowpack with layers of weak snow near the ground and mid-pack. Triggering an avalanche on the above layer could step down and trigger a very large avalanche deeper in the snowpack.
With skies remaining overcast and little incoming precipitation today, avalanches on steep slopes at low elevations are less likely. If this storm produces enough moisture over the next 72 hours, rain and warm midday temperatures may start to peel snow off of these areas in the form of wet avalanches.
(3/26/2023)
Mosquito Creek Area remote triggered avalanche that failed on March 20th weak layer. 2-3' crown depth. D2 R3
Photo: Will Mook