Avalanche Forecast

Issued: Mar 12th, 2018 3:51PM

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

mbender, Avalanche Canada

Kootenay Boundary.

Expect avalanche danger to increase as the temperature rises through the day. Danger ratings are rated for the heat of the day when the likelihood of avalanches triggering is highest.

Summary

Confidence

Moderate - Freezing levels are uncertain on Wednesday

Weather Forecast

TUESDAY: Mix of sun and cloud / Moderate south wind / Alpine temperature 7 / Freezing level 2700mÂ WEDNESDAY: Mainly cloudy with isolated flurries or rain showers / Light southwest wind / Alpine temperature 5 / Freezing level 2300mÂ THURSDAY: Mix of sun, cloud and isolated flurries / Light south wind / Alpine temperature -1 / Freezing level 1400mÂ

Avalanche Summary

Avalanche activity through the end of the weekend into Monday focused on a natural solar induced loose wet avalanche cycle on south and west aspects in the alpine an treeline to size 2. On Friday reports indicate numerous size 2-2.5 natural and explosive controlled storm snow avalanches running on all aspects in the alpine and at tree line. There were also several skier triggered storm slab avalanche size 1.5-2 both Friday and Saturday on north aspects in the alpine and tree line.

Snowpack Summary

Last week's snow has settled and been redistributed by predominantly west and southwest wind on upper shady aspects or has become moist or wet and/or refrozen (depending on the time of day) on slopes facing the sun. On sheltered northerly aspects it may be sitting on a layer of surface hoar.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

Loose Wet

Surface crusts on sun exposed slopes will break down quickly in the heat of the day. Expect to see the surface snow sluff and gather mass in steep terrain as the day warms up.

Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2.5

Wind Slabs

Fresh storm and wind slabs have formed with recent new snow and moderate southwesterly wind.

Be cautious as you transition into wind affected terrain.Extra caution needed around cornices with current conditions.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Persistent Slabs

Weak layers exist 40-100 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.

Avoid convexities or areas with a thin or variable snowpack.Be cautious on convex rolls at and below treeline where buried surface hoar may be preserved.If triggered smaller avalanches may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1.5 - 3

Valid until: Mar 13th, 2018 2:00PM