Avalanche Forecast

Issued: Mar 9th, 2018 4:15PM

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

mbender, Avalanche Canada

Kootenay Boundary.

Expect to see the first real warmup of the season with clear skies and rising freezing levels through the weekend into next week. This will initially impact the new snow that fell on Friday, especially on solar aspects.

Summary

Confidence

Moderate - Freezing levels are uncertain on Sunday

Weather Forecast

SATURDAY: Mix of sun and cloud / light south wind / Alpine temperature -3 / Freezing level 1400m SUNDAY: Mix of sun and cloud / Light to moderate south wind / Alpine temperature 0 / Freezing level 1800m MONDAY: Mix of sun and cloud / Light south wind / Alpine temperature 3 / Freezing level 2300m

Avalanche Summary

Expect to see an increase in storm slab, wind slab and loose wet and dry avalanche activity as new snow from Thursday night settles and gets kissed by the sun. On Friday reports indicate a few size 2.5 explosive controlled storm snow avalanches running on south aspects at tree line. On Wednesday reports indicated loose wet avalanches size 1.5-2 from southerly facing terrain at tree line. On Tuesday, a size 1 wind slab was skier-triggered on a south aspect at 2200 m and nearby explosive control produced a size 2 wind slab.

Snowpack Summary

15-35cm of new snow has been redistributed by predominantly west and southwest wind and sits on mostly unconsolidated snow from last week and possibly on a sun crust on south-facing slopes.A mix of weak layers exist 50-100 cm below the surface, including small surface hoar on shady aspects and a crust on solar aspects. These layers have consistently been reactive in snowpack tests, suggesting they could potentially remain reactive to human triggers as well. Deeper weak layers that formed in January and December have gained strength and gone dormant at this time. They include several surface hoar and facet layers 1 to 2 m below the surface and a crust/ facet interface near the base of the snowpack.

Problems

Storm Slabs

Fresh storm and wind slabs have formed with up to 35cm of new snow in some parts of the region combined with moderate southwesterly wind. With sun and warm temperatures in the forecast expect to see loose wet avalanches as well.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.Extra caution needed around cornices with current conditions.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Persistent Slabs

Weak layers exist 50-100 cm below the surface, including surface hoar on north-facing terrain and sun crusts on south-facing terrain. These layers may become reactive with the weight of new snow and warming.

Be cautious on convex rolls at and below treeline where buried surface hoar may be preserved.Avoid convexities or areas with a thin or variable snowpack.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1.5 - 3

Valid until: Mar 10th, 2018 2:00PM