Avalanche Forecast

Issued: Apr 6th, 2016 8:35AM

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

pmarshall, Avalanche Canada

Cariboos.

It will almost feel like summer for the next couple days. The heat and sunshine will cause the avalanche danger to rise during the day, especially on solar aspects. Choose terrain carefully.

Summary

Confidence

High

Weather Forecast

THURSDAY: Cloudy but clearing throughout the day. The freezing level shoots up to 3200 m. Winds should ease to light and variable. FRIDAY: Mainly sunny. The freezing level stays well above 3000 m and winds should remain light. SATURDAY: A mix of sun and cloud. The freezing level could drop to 2500 m and winds could kick up to moderate from the west.

Avalanche Summary

Several small (size 1) storm slabs were triggered in steep convex-shaped north-facing terrain on Tuesday. There was also one report of a natural cornice fall that triggered a size 3.5 deep persistent slab on a north-facing alpine slope. As we move back to warm and sunny weather I would expect renewed loose wet activity on solar aspects, natural cornice falls, and isolated large persistent and wet slab avalanches.

Snowpack Summary

20-40 cm of new snow sits on melt-freeze crust with westerly winds forming fresh wind slabs in exposed lee and cross-loaded terrain. The March 22nd rain crust is buried 50-70 cm deep up to around 2000 m. We could see more activity on this layer when temperatures soar later in the week. The late February persistent weak layer is now down 60 to 120 cm below the surface. While it may be a concern in isolated terrain, it would probably take a large trigger like a cornice fall or surface avalanche in motion to provoke it. The lower elevation snowpack (below 1500 m) is moist and isothermal.

Problems

Loose Wet

Fresh snow followed by rapid warming and strong spring sunshine are a perfect recipe for a fairly widespread loose wet avalanche cycle.

Be alert to conditions that change with elevation.>Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 3

Cornices

Cornices could fail easily during the day when temperatures soar and the sun reappears.

Give cornices a wide berth when travelling on or below ridges.>Cornices become weak with daytime heating, so travel early on exposed slopes.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 5

Persistent Slabs

Intense solar radiation, a heavy wet surface sluff, or a cornice fall could be enough to trigger lurking deep weaknesses.

A buried persistent weak layer (PWL) is lurking in our snowpack which means there is potential for large destructive avalanches that have the capability to run full path.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Apr 7th, 2016 2:00PM