Archived

Avalanche Forecast

Mar 7th, 2013–Mar 8th, 2013

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

2: Moderate

The avalanche danger rating below treeline will be moderate

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

2: Moderate

The avalanche danger rating below treeline will be moderate

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: South Coast.

Avalanche danger below treeline is LOW in the Cascades where the surface rain crust extends up to higher elevations.

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

Friday: Mix of sun and cloud / Light northwest winds / Freezing level at 1600mSaturday: Clear skies / Light northwest winds / Freezing level at 1700mSunday: Light snowfall / Moderate southwest winds / Freezing level at 1200m

Avalanche Summary

There were no reports of new avalanches on Monday, Tuesday or Wednesday. Sun forecast for Friday and Saturday could trigger loose wet avalanche activity on steep solar features. Warming also has the potential to trigger deeper persistent slab avalanches.

Snowpack Summary

Light amounts of recent snow overlie 60-100cm of settling storm snow or a rain crust below 1400m in the north and 1700m in the south. These accumulations may exist as wind slabs in exposed areas.A weak layer of buried surface hoar (February 20th) and/or a crust sits at the base of the storm snow. This layer was the culprit in most of the large avalanches that occurred last weekend. Snowpack tests continue to show sudden planar results and good potential for propagation. Triggering this layer is becoming more difficult, but I recommend avoiding any large slopes that did not release during the last cycle, especially when the sun pokes out this week.

Avalanche Problems

Persistent Slabs

60-120 cm of settling storm snow sits on a persistent weak layer of surface hoar. Extra caution should be given on all slopes over 30 degrees that did not previously slide, especially if the sun comes out.

Conditions have improved, but be mindful that deep instabilities are still present.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 2 - 7

Loose Wet

With forecast sun, loose wet avalanches will become likely on steep, sun-exposed slopes.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 3

Wind Slabs

Although wind slabs have gained strength, they may still be reactive in steep, unsupported terrain.

Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 3