Recent storm snow coupled with warming has formed a reactive slab that rests on the early January interface and deeply buried weak layers in our complex snowpack remain sensitive to human triggering. Continue to choose low angle conservative terrain.
Summary
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain on Thursday
Weather Forecast
The parade of Pacific storms will continue across southern B.C for the next several days, keeping alpine snow packs building through Thursday. The next system on Wednesday will be weak and affect mainly the south coast. Thursday's storm will be the main event of the week and feature moderate to heavy snow for the south coast alpine and much of the interior. The biggest snow accumulations this week will be over the South Coast and Interior Ranges, from the Columbias down to the US border.WEDNESDAY: Overcast, freezing level around 500 m, moderate west wind, 1 to 5 cm of snow possible. WEDNESDAY NIGHT: Freezing level at valley bottom, light to moderate southwest wind, 1 to 5 cm of snow possible.THURSDAY: Freezing level at valley bottom, moderate southwest wind, 10 to 15 cm of snow possible.FRIDAY: Overcast, freezing level at valley bottom, light to moderate west wind, no snow expected.
Avalanche Summary
On Tuesday a widespread natural avalanche cycle to size 2.5 was reported from all aspects and elevations as the upper snowpack adjusted to a new load and increasingly warm temperatures.Last Thursday a skier triggered a size 3.0 avalanche just after entering the east face of Evening Ridge at 2000 m near Nelson. The avalanche released to ground and the late November crust was likely involved. The avalanche caught and carried the skier for over 300 m, resulting in significant injuries. Subsequent avalanche control in the area produced two additional size 2.5 avalanches. On New Years Eve a size 3 avalanche on an east facing treeline feature at Kootenay Pass resulted in a single fatality. A crown profile has shown that this avalanche failed on the late November crust.
Click here to see the Mountain Information Network report for this incident.Snowpack Summary
20 to 50 cm of new snow now sits on a crust on steep southerly aspects and/or a newly formed layer of surface hoar that was buried January 5th.A surface hoar layer buried late in December is now 40 to 80 cm deep. The mid-December surface hoar is now down 60 to 110 cm below the surface. This layer is most pronounced at treeline, but is present below treeline also. The overlying slab is now deep and is gaining cohesion with time and continued warm temperatures, as evidenced by recent avalanche activity listed above.Two laminated crusts created by twin rain events in late November lay just below the mid-December interface, 70 to 110 cm below the surface. Facets may be found sandwiched between the two crusts and have been observed above the uppermost crust too. In shallow rocky terrain the mid-December surface hoar and the late November crust seem to be reacting together which is a volatile combination.
ghelgeson,
Avalanche Canada
