Archived

Avalanche Forecast

Feb 22nd, 2015–Feb 23rd, 2015

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

1: Low

The avalanche danger rating at treeline will be low

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

1: Low

The avalanche danger rating in the alpine will be low

Treeline

1: Low

The avalanche danger rating at treeline will be low

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

1: Low

The avalanche danger rating in the alpine will be low

Treeline

1: Low

The avalanche danger rating at treeline will be low

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: South Columbia.

Keep an eye on the temperatures on Monday. Solar radiation and rising freezing levels can weaken the snowpack and make destructive avalanches more likely.

Confidence

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

Weather Forecast

The dry ridge will persist throughout the forecast period bringing a mix of sun and cloud until Wednesday. Winds will generally remain light from the northwest, although strong gusts are likely on Tuesday. On Monday we can expect an inversion with above-freezing alpine temperatures. Freezing levels will hover around 1500m on Tuesday, and then drop to about 800m on Wednesday.

Avalanche Summary

Avalanche activity has gradually tapered off throughout the past week, although there has been some wind slab activity to size 1.5 at higher elevations over the weekend in response to northwest to northeast winds redistributing recent snow accumulations. Looking forward, wind slabs may remain sensitive to human triggering, while loose wet avalanches may fail under sunny skies and rising freezing levels on Monday.

Snowpack Summary

Up to 10 cm of recent snow covers the previous variable snow surface of surface hoar, crusts, dry facetted snow, or wind affected snow depending on aspect and elevation. The "Valentine's Day" crust is just below the surface and is now strong and thick in most places. New wind slabs may have formed in lee terrain from recent W-NW winds, and cornices remain large and weak. The late-Jan crust/surface hoar layer (up to 100 cm deep) and the mid-January surface hoar (80-120 cm deep) are generally dormant, and chances of triggering these weaknesses have decreased. However, triggering may be possible with a large input such as cornice fall, or an avalanche stepping down, especially on sun drenched slopes.

Avalanche Problems

Wind Slabs

Gusty northwest winds may have redistributed recent accumulations into fresh wind slabs in higher elevation terrain. Warming on Tuesday may reactive these wind slabs and also promote loose wet avalanches on sun-exposed slopes.

Avoid travelling in areas that have been reverse loaded by winds.>Use ridges or ribs to avoid pockets of wind loaded snow.>Give cornices a wide berth when travelling on or below ridges.>Watch for clues, like sluffing off of cliffs, that the snowpack is warming up. >

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 3

Persistent Slabs

Persistent weak layers have been generally dormant as of late. That said, I'd watch my overhead hazard and be increasingly cautious in steep, unsupported terrain, especially with warming forecast for Monday afternoon.

Avoid common trigger points like steep convexities or areas with a thin or variable snowpack.>Avoid areas with overhead hazard.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Unlikely

Expected Size: 3 - 5