So far the warmth & sun has not destabilized the snowpack too much. With more days of sun and warm alpine temperatures forecast, keep reducing your exposure to steep solar terrain during the heat of the day.
Watch for old and fresh wind slabs in the alpine, and open "alpine like" features at treeline. These slabs may be poorly bonded to underlying crust and surface hoar layers. These old wind slabs may become reactive with above freezing temperatures and/or afternoon sun, especially on steeper terrain features and solar aspects.
As the temperature inversion rebuilds Friday, above freezing alpine temperatures and direct sun will moisten snow and deteriorate snow stability, particularly on steep solar slopes with direct sun.
After a brief cooling trend overnight, a temperature inversion continues to dominate the forecast period in Southeast BC bringing warm sunny conditions to the alpine while the valleys remain cooler.
THURSDAY NIGHT: The temperature inversion will weaken overnight bringing freezing levels to valley bottom. Winds will be moderate to strong West/Northwest, variable cloud cover & no precipitation is expected.
FRIDAY: An alpine temperature inversion will rebuild throughout the day with a mix of sun and clouds, above freezing temperatures (+2 to +5C) are forecast between 2000m and 3000m in the alpine while valleys remain cool, winds ease to light to moderate North/North-Westerly, & no precipitation expected.
SATURDAY: Above freezing temperatures (+3 to +8C) as the temperature inversion strengthens in the Alpine, moderate to strong Westerly wind, no precipitation expected.
SUNDAY: The temperature inversion beings to weaken by days end with above freezing alpine temperatures and cool valleys, moderate Westerly winds, no precipitation expected.
There were minimal reports of natural or human triggered avalanche activity despite above freezing alpine temperatures and sun on Wednesday (with highs of +5 to+10) and Thursday (with highs of +1 to +3). Reports from field teams and adjacent regions were limited to pinwheeling, small to medium loose wet slides (to size 1.5) from steep solar terrain, and isolated small slab avalanches with explosives.
Concern remains for the above freezing temperatures in the alpine on steep solar aspects and windslabs on northerly terrain. Thursday night's cooling will improve snowpack stability ahead of Friday and Saturday's warming. However, alpine temperatures are forecast to rise to +5 to +10 again at the peak of the warmth on Saturday.
Observations are limited right now, but there have been no reports of recent large avalanches. We appreciate the recent reports submitted to the Mountain Information Network. Keep them coming!
Alpine and exposed ridge crests have been heavily affected by recent winds. Winds scoured ridges and redistributed last week's 10-20cm of snow into windslabs on cross-loaded and lee-slope features.
These slabs may sit above a layer of surface hoar in sheltered terrain and above a widespread hard rain crust (Nov 5 rain crust). This Nov 5 rain crust is found up to 2500m and may become a weak layer where overlaid by windslab.
Moist snow during the heat of the day and variable refrozen crusts can be found on solar aspects. Below the temperature inversion (~2000m) snow continues to facet and soften.
Snowpack depths at sheltered upper treeline elevations are nearing 100 cm and beginning to exceed the threshold for avalanches, while the snowpack is much thinner in the valleys and wind scoured locations.
The lower snowpack consists of crusts. Weak snow may be developing around these crusts in some areas, which will be a snowpack feature to monitor as the season progresses.
