Avalanche Forecast

Issued: Nov 25th, 2015 8:23AM

The alpine rating is below threshold, the treeline rating is below threshold, and the below treeline rating is below threshold. Known problems include Wind Slabs and Loose Wet.

Avalanche Canada swerner, Avalanche Canada

The snowpack is extremely variable depending on aspect and elevation and does not adjust well to rapid change. Watch for rising alpine temperatures to well above zero. Check out the Mountain Information Network. Give info, get info!

Summary

Weather Forecast

The high pressure ridge continues to dominate the coastal regions. Strong alpine temperature inversions will be prominent with warm air above 1000 m ranging from 0-5 degrees. Moderate to strong outflow winds will prevail in coastal valleys. Valley cloud may accompany the strengthening temperature inversion and outflows will diminish Saturday as pacific air starts to move into the north. By Sunday the weather pattern may see change, however; timing and intensity of the next Pacific system is hard to pin point due to disagreement between the Canadian model and the GFS.

Avalanche Summary

No new avalanches have been reported. This may speak to a lack of observations rather than actual conditions. Newly formed wind slabs may remain sensitive to human triggering and surface snow may start to deteriorate especially on solar aspects with the warming. Watch for obvious clues of instability like natural avalanches, snow balling and moist/ wet snow.

Snowpack Summary

The snowpack is extremely variable depending on aspect and elevation, with new wind slabs developing on reverse loaded southerly slopes and widespread surface crusts on all aspects at lower elevations. At upper elevations, last weekends storm likely produced stiff wind slabs on northerly aspects. The reactivity of these new wind slabs will likely change with elevation and underlying snowpack structure. The snowpack doesn't adjust well to rapid changes, so it may take several days to adjust and settle with the warm temperatures at higher elevations. Due to limited observations, I have very little confidence in what that underlying structure may be, although I suspect faceting, crusts and surface hoar may exist. How are they adjusting and reacting as shears? Are they distinct and reacting like a cash register when tested? Or are they becoming hard to find with resistant shear characteristics? If I were traveling in the mountains, I'd maintain a conservative and investigative approach and dig down to test for weak layers before committing to a slope.

Problems

Wind Slabs

An icon showing Wind Slabs
New wind slabs are likely on opposite slopes due to changing winds from the north. Last weekend's storm may have formed hard wind slabs at higher elevations, watch for wide propagations, especially in the lee of ridgecrests.
Be aware of the potential for wide propagations due to the presence of hard windslabs.>Be alert to conditions that change with elevation and use a cautious approach to terrain while gathering information along the way.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Loose Wet

An icon showing Loose Wet
Strengthening warm air aloft (above 1000 m) will likely deteriorate snow surfaces initiating loose wet avalanches. Smaller avalanches could dig down to deeper layers, especially at higher elevations, initiating larger slab avalanches.
Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>With these very warm temperature inversions, use extra caution, on or near sunny slopes above treeline. >

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Nov 26th, 2015 2:00PM

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