Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Jan 9th, 2018–Jan 10th, 2018

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.

Regions

Kootenay Boundary.

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.

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.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.