Archived

Avalanche Forecast

Mar 19th, 2012–Mar 20th, 2012

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Northwest Inland.

Confidence

Fair - Forecast snowfall amounts are uncertain

Weather Forecast

Tonight and Tuesday: Moderate snowfall - Approximately 5cm overnight and an additional 5-10cm on Tuesday. The freezing level (FL) is around 500m and winds are moderate from the S-SW. Wednesday: Unsettled conditions with convective flurries - 5cm. FL is near 500m. Winds easing to light from the south. Thursday: Mainly cloudy with light flurries. No significant accumulation.

Avalanche Summary

The soon to be buried snow surface includes a sun crust on southerly aspects, surface facets or surface hoar in cool shady areas, and pockets of wind slab in exposed terrain. The mid February persistent weak layer interface, comprised of spotty surface hoar, facets and crusts, is buried 80-120 cm below the surface. No recent activity has been reported on this interface. However, recent snowpack tests have been giving hard but sudden "pop" results and indicate it is has the potential to react given the right trigger in the right place. For route selection, it should still be on your radar and is more likely to be triggered on steeper, unsupported terrain. Cornices in the area are reported to be very large and primed for natural collapse or triggering by a person.

Snowpack Summary

No new slab avalanches have been reported in the past day or two. There were a few reports of cornice failures, but most did not trigger slabs.

Avalanche Problems

Wind Slabs

New wind slabs may form in exposed lee and cross-loaded features on Tuesday.

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

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 4

Cornices

Large cornices exist in alpine terrain. A failure could be destructive by itself, and could also trigger an avalanche on the slope below.

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

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1 - 6

Persistent Slabs

The likelihood of triggering persistent layers buried in early February is greatest on steep, unsupported terrain . Although no recent avalanches have been reported, the chances of triggering may increase with solar radiation forecast for the weekend

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 3 - 6