We will be providing an AIARE Avalanche Level 1 Class this winter in Haines, February 23-25, 2018
Above 2,500ft Considerable
1,500 to 2,500ft Considerable
Below 1,500ft Considerable
Degrees of Avalanche Danger ?
Human-triggered avalanches will be likely today on wind loaded slopes, convexities, and steep slopes/gullies. This applies below treeline as well, in any open paths or sparse trees.
The main concern will be new storm snow and wind slabs from last week that sit at the top of the snowpack. These slabs (10-50cm thick) are sitting on a layer of weak facets. Due to persistent cold weather, the new storm snow and slabs underneath are not bonding well at all.
Our current alpine snowpack is characterized thus: 2-5mm depth hoar at the ground, with a pencil-hard rain crust above, then varying wind-packed and fresh storm layers above that. The new storm snow will be quite weak and prone to sliding anywhere it can form a cohesive slab.
A few notes:
- We have an extreme lack of snow so far this season. Total precipitation since October 1st is at 38% of normal. Snow depths are between 45-100cm in most areas. Variability is high due to persistent dry, windy conditions before this week. There are lots of rocks lurking under the new snow and we still don’t have a solid base.
- Temperatures above treeline have been around 0 – 5°F. This has caused faceting of the thin snowpack and built up 3-5mm depth hoar. This will be a weak base to hold up future heavy snows. Keep this in mind as November progresses and snow depths increase. This will likely turn into a deep-persistent slab problem.
Start the season with fresh batteries in your beacon, and practice with your beacon, shovel, and probe.
If you get out on the snow, send in your observations!
Recent Avalanche Activity
October 28th: First rider-triggered slide reported from the peak north of Nadahini (“Sunny Bunny”). D2 soft slab ran in storm snow from Oct 26-27. Nobody caught or injured. [ SS-AR-D2-R3-S ] South aspect @ 6,200ft.
Small – Moderate natural avalanche activity is occurring during/after storms. So far it has been mostly loose-snow slides, with a few slab avalanches as well.
A short break in the weather on Tuesday will lead to a strong front Tuesday night, with 12-18″ possible. Snow levels will rise to around 1,000ft Wednesday after the bulk of the storm has already hit. Expect snow levels to drop back down to sea level from Wed. night on, with several more inches of accumulation.
|Snow Depth [in]||Last 24-hr Snow/SWE [in]||Last 3-days Snow/SWE [in]||Today’s Freezing Level [ft]||Today’s Winds||Next 24-hr Snow/SWE|
Mount Ripinsky @ treeline
|6″ / 0.30||6″ / 0.30||0||light, var||16″ / 0.80 *|
Flower Mountain @ treeline
|3″ / 0.15||3″ / 0.15||0||light, var||12″ / 0.60 *|
Chilkat Pass @ 3,500ft
|12″ *||2″ / 0.10 *||2″ / 0.10||0||light, var||6″ / 0.30 *|
( *star means meteorological estimate )