Avalanche Forecast

Issued: Feb 25th, 2014 8:02AM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Persistent Slabs and Wind Slabs.

swerner, Avalanche Canada

Kootenay Boundary.

Don't let the good weather lure you into terrain with consequences. The snowpack remains complex. Avalanche danger can rise rapidly with full sunshine, especially on solar aspects.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

The strong arctic ridge of high pressure that has been dominating the Interior Regions will begin to retreat on Wednesday, bringing warmer temperatures and rising freezing levels. Some disturbances in this flow will bring cloudy skies later tin the forecast period.Wednesday: Sunny and 0.0 degrees expected at treeline. Ridgetop winds will be light from the NW. Freezing levels 1300 m.Thursday: Cloudy with sunny periods and 0.0 degrees at treeline. Ridgetop winds 20 km/hr from the NW. Freezing levels near 1500 m.Friday: Cloudy with sunny breaks and light flurries. Treeline temperatures -9.0 and ridgetop winds will be light from the NE.

Avalanche Summary

Skier remote triggered avalanches are continuing to surprise people up to size 2, while an explosive control mission also showed several slab avalanches up to size 2.On Sunday, a skier triggered size 2.5 was reported. Party of three with two involved. Sadly RCMP reported one fatality and the other suffered serious injuries. The crown was near 100 cm deep and released near ridgetop in storm snow and then stepping down to the persistent weak interface and running a far distance through the trees. With forecast sun, the avalanche hazard will likely increase on solar slopes.Check out the Forcaster Blog! It shows a photo of a remote triggered size 3 last Friday in the southern part of the Kootenay-Boundary.

Snowpack Summary

Changing winds from the southwest-north may build fresh wind slabs on leeward slopes and new surface hoar formation 5-10 mm has been noted. Currently there is over a metre of recent storm snow that is sitting on a weak layer comprising of facets, surface hoar, melt-freeze crusts and any combination of these. The weak layer is widespread at all elevations and aspects and continued whumpfing and easy sudden planar snowpack test results are being reported. The storm slab continues to settle and become more cohesive allowing for longer fracture propagations and remote triggering from up to 200 m away, yikes! This persistent weak layer is expected to be a concern for some time; at all elevations and aspects. Treeline and below treeline elevations is catching many people by surprise.With forecast sunny periods, solar aspects will likely see moist snow during the day, then forming a crust overnight.

Problems

Persistent Slabs

Expect the deeply buried weak layers to continue to produce large and destructive avalanches. Slopes are primed for human triggering and remain a concern on all aspects and elevations.

Avoid areas with overhead hazard, especially on solar aspects.>Remote triggering is a big concern, be aware of the potential for wide propagations and large, destructive avalanches at all elevations.>Use conservative route selection and resist venturing out into complex terrain, even if you observe no obvious signs of unstable snow.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

3 - 6

Wind Slabs

Wind has transported snow and built fresh, touchy wind slabs. Be aware of weak cornices looming over slopes. If they fail, they will likely trigger a large slab avalanche on the slope below.

Extra caution needed around cornices with current conditions.>Avoid freshly wind loaded features.>Caution in lee and cross-loaded terrain near ridge crests.>

Aspects: North, North East, East, South East, South.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Valid until: Feb 26th, 2014 2:00PM