Avalog Join
Archived

Avalanche Forecast

Apr 20th, 2013–Apr 21st, 2013
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
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
Below Threshold
The avalanche danger rating in the alpine will be below threshold
Treeline
Below Threshold
The avalanche danger rating at treeline will be below threshold
Below Treeline
Below Threshold
The avalanche danger rating below treeline will be below threshold

Regions: South Columbia.

The Public Avalanche Forecasts and Danger Ratings will come to an end on Tuesday. General spring messaging will be found under the Forecast Details tab below.

Confidence

Fair - Due to limited field observations

Weather Forecast

The Interior will remain under a cool, dry North-West flow through Tuesday. A slow warming trend will persist through the end of next week.Sunday: Scattered-broken cloud cover, allowing some sunshine through.  Ridgetop winds will blow light from the North. Freezing levels 1400 m and falling to valley bottom overnight.Monday/Tuesday: Mostly clear, sunny skies. Ridgetop winds will blow light from the NW. Freezing levels 1700 m in the afternoon and falling to 1000 m overnight.

Avalanche Summary

On Friday, reports of the new storm snow was sluffing from steep terrain up to size 2. 

Snowpack Summary

At higher elevations up to 25 cm of new snow sits on a series of melt-freeze crusts (solar aspects) and some smaller surface hoar crystals (northerly aspects). Touchy wind slabs exist on lee slopes and behind terrain features and cornices are huge, threatening slopes below.Deeper in the snowpack (60-120 cm down) a weaker interface exists comprising of crusts, and surface hoar. Earlier this week, very large avalanches were reactive on this interface in the neighboring Glacier National Park. I would practice caution and remain suspicious of steeper, high alpine slopes.

Avalanche Problems

Wind Slabs

Wind slab problems exist on lee slopes and behind terrain features at treeline and above. Large looming cornices exist on ridgelines and pose a threat to slopes below. Keep well back and watch your overhead hazards.
Use ridges or ribs to avoid pockets of wind loaded snow.>Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.>

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 4

Persistent Slabs

On Monday, an interface buried down about 60-120 cm created surprisingly large avalanches in neighboring regions. Smaller avalanches, cornice fall or the weight of a person hitting a thin-spot, may trigger a large avalanche & destructive avalanche.
Be aware of thin areas that may propagate to deeper instabilites.>Dig down to find and test weak layers before committing to a line.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Unlikely - Possible

Expected Size: 1 - 6