Avalanche Forecast
Issued: Dec 23rd, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs.
cgarritty,
Avalanche Canada
A soft blanket of new snow has once again improved riding conditions, but it obscures a minefield of wind slabs that can't quite be trusted yet. Keep avoiding those leeward features and watch for any uptick in winds to build up new slabs with the plentiful snow available.
Summary
Confidence
Weather Forecast
WEDNESDAY NIGHT: Diminishing cloud with easing flurries leaving a final trace of new snow. Moderate west winds.
THURSDAY: Becoming clear with about 30 cm of new snow on the ground. Light winds shifting from west to east by evening. Alpine high temperatures around -7.
FRIDAY: Sunny. Light northeast winds. Alpine high temperatures around -12.
SATURDAY: Mainly sunny. Light variable winds. Alpine high temperatures around -9, cooler at lower elevations under a mild temperature inversion.
Avalanche Summary
Preliminary observations from Wednesday's storms detailed low density new snow not reacting to skier traffic. Serious concern still exists for older wind slabs, now obscured by the cover of new snow and not yet beyond the reach of human or machine triggering.
On the weekend, two large (audible) natural slides were noted on Saturday by the Yukon field team as they performed snowpack observations near the summit of White Pass.
Until winds once again have a go at our new snow, the most likely place to trigger an avalanche is likely still on the leeward (think north through east) side of ridges and ribs where wind slabs were most recently formed. Don't allow the low density surface snow to cloud your assessment of these buried hazards.
Snowpack Summary
About 30 cm of low density new snow fell on Wednesday in White Pass, burying an array of wind affected surfaces and recent wind slabs. Winds were reportedly light or even calm during the storm.
Buried wind slabs remain a real concern, as well as any new wind slabs that may have formed at higher elevations during the storm, even if the extent of this slab formation was limited.
A widespread melt-freeze crust now exists at an estimated 40-60 cm deep in the region, under our two most recent storm snow layers. This crust has been reported up to 1400 m in the Wheaton Valley, up to 1800 m near the Alaska border.
The lower snowpack is generally settled and strong after a big storm at the beginning of December. However, there is potential for weak snow to persist at the bottom of the snowpack in colder, thinner snowpack areas such as the Wheaton Valley.
Terrain and Travel
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- Avoid terrain traps where the consequence of any avalanche could be serious.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
Problems
Wind Slabs
The primary concern is buried wind slabs lurking beneath our low density new snow on the leeward sides of ridges, ribs, and rolls in the terrain.
Watch for any uptick in wind in coming days creating touchier new slabs with the plentiful new snow available for wind transport.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 25th, 2020 4:00PM
