Avalanche Forecast
Issued: Dec 19th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs.
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Avalanche Canada
My primary concern is wind slabs behind ridges, ribs, and rolls. My second concern is the warm temps turning the snow "upside down" -- if the snow is warm & dense at the surface, cold and soft below increase caution on steeper rolls irrespective of aspect or wind effect.
Summary
Confidence
Weather Forecast
Even if the days are short, sunny weather is returning.
SATURDAY NIGHT Light snow ending overnight. Southerly winds lighter at lower elevations, moderate to strong up high. Temps near zero in White Pass
SUNDAY: Clearing sky, no new snow, cooler temps around -5 to -10 C near White Pass, continued light to moderate southwest winds.
MONDAY: very similar to Sunday, just a touch cooler with temps around -10 C near Whitepass.
TUESDAY: no new snow, moderate southerly winds, continued -5 to -10 C temps with a mix of sun and clouds.
Avalanche Summary
There have been no recent reports of avalanches in the region. The only reports we've received are of exceptional powder riding.
The most likely place to trigger an avalanche is on the leeward side of a ridges and ribs where new wind slabs were formed.
Snowpack Summary
Snowpack is 200 cm in Whitepass, closer to 100 cm in drier areas like the Wheaton.
Eight to ten hours of moderate to strong southwest winds overnight Friday & early Saturday morning build wind slabs and cornices; the key question is how widespread and sensitive the upper snowpack is.
Below this surface snow lies a widespread melt-freeze crust. The 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 massive storm at the beginning of December. However, there is potential for weak snow at the bottom of the snowpack in colder drier areas such as the Wheaton Valley.
Terrain and Travel
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Avoid terrain traps where the consequence of any avalanche could be serious.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Problems
Storm Slabs
My primary concern is wind slabs behind ridges, ribs, and rolls in the terrain. My second concern is the warm temps turning the snow "upside down" -- if the snow is warm & dense at the surface, cold and soft below increase caution on steeper rolls irrespective of aspect or wind effect.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 21st, 2020 4:00PM
