Avalanche Forecast

Issued: Apr 8th, 2018 3:46PM

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

ghelgeson, Avalanche Canada

Cariboos.

A buried persistent weak layer may roar back to life over the next few days as the freezing level rises and the sun comes out. South facing slopes are especially suspect and are best avoided at this time.

Summary

Confidence

Moderate - Timing or intensity of solar radiation is uncertain on Monday

Weather Forecast

Monday, most of BC will receive partly cloudy conditions with a few lingering flurries in the Cariboos. A warm system makes landfall Tuesday morning, which should open the door to rain and wet snow into the alpine on Tuesday and Wednesday.MONDAY: Broken cloud cover, freezing level beginning around 1200 m rising to about 1900 m, light to moderate westerly wind, trace of precipitation possible. TUESDAY: Scattered cloud cover, freezing level holding around 2000 m, light to moderate southerly wind, trace of precipitation possible.WEDNESDAY: Scattered cloud cover, freezing level beginning around 1500 m rising to about 1700 m, moderate to strong southwest wind, 2 to 10 mm of precipitation possible.

Avalanche Summary

No new avalanche activity reported Saturday.Only small loose dry avalanches (sluffing) to size 1 were reported from east facing aspects around treeline on Friday.Reported avalanche activity on Thursday was limited to a size 2 natural cornice failure on a southeast facing slope at 2900 m.

Snowpack Summary

Up to 10 cm of new snow fell Saturday with light variable wind. This snow rests on crust that is present on all aspects below 2000 m, and extends up to about 2500 m on south facing aspects. The storm snow be sitting on surface hoar on polar aspects (north and east) at upper elevations. The main concern is the mid-March Persistent Weak Layer (PWL) which is now 60 to 100 cm below the surface. This layer is composed of a crust on all aspects at low elevations. At upper elevations the layer presents as a crust on solar aspects (those that face south and west) and buried surface hoar on polar aspects. The reactivity of this interface has been steadily decreasing and while the likelihood of triggering a deeper persistent slab avalanche is lowering, the consequence of doing so remains high. Solar aspects are expected to be the most suspect as the freezing level begins to rise over the next few days.Deeper persistent weak layers from January and December are still being reported by professional observers, but are generally considered dormant.

Problems

Persistent Slabs

Weak crust and surface hoar 60 to 100 cm below the surface have shown prolonged reactivity since the last major storm. South facing features have been the most reactive, a trend that is expected to continue as temperatures rise Monday and Tuesday.

Be aware of the potential for large, deep avalanches.Minimize exposure to steep planar south-facing slopes - especially if they see sunshine.Use caution around sheltered steep or convex slopes where buried surface hoar may be preserved.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Storm Slabs

Up to 10 cm of snow fell Saturday with light southerly wind which may have formed shallow wind slabs immediately lee of ridge crest. Warming temperatures and brief periods of sun Monday may initiate natural storm slab and loose avalanche activity.

Be cautious of sluffing in steep terrain.Minimize exposure to steep, sun exposed slopes when the sun is out.Be careful with wind loaded pockets near ridge crests and roll-overs.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 1.5

Valid until: Apr 9th, 2018 2:00PM