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Avalanche Forecast

Archived

Nov 22nd, 2015–Nov 23rd, 2015

Alpine
Below Threshold.
Treeline
Below Threshold.
Below Treeline
Below Threshold.
Alpine
Below Threshold.
Treeline
Below Threshold.
Below Treeline
Below Threshold.
Alpine
Below Threshold.
Treeline
Below Threshold.
Below Treeline
Below Threshold.

Regions

Northwest Inland.

Given the very limited information on hand for this bulletin, I would tread cautiously and take the time to gather snowpack information as I go. As always, we would love for you to submit any observations from your day to the MIN.

Confidence

Poor - Due to the number of field observations

Weather Forecast

Lingering cloud may persist on Monday, but a general clearing trend is expected for the forecast period as a cool ridge of high pressure sets up over the region. Ridgetop winds should remain northerly, peaking on Monday at about 80kmh, then decreasing somewhat on Tuesday and Wednesday. Ridgetop temperatures should remain between -12 and -17 for all three days.

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 for the next few days, especially in areas with buried persistent weak layers.

Snowpack Summary

Reactive wind slabs are expected to have formed as a result of new snow, warm temperatures and strong westerly winds on Friday and Saturday. At lower elevations precipitation fell as rain, and more recent cooling has formed a refrozen crust. The reactivity of these new wind slabs will likely change with elevation and underlying snowpack structure. Due to limited observations, I have very little confidence in what that underlying structure may be, although faceting and surface hoar development may have occurred on shaded terrain. If I were traveling in the mountains, I'd maintain an investigative approach and dig down to test for weak layers before committing to a slope. If you've been in the mountains, please share your observations on our Mountain Information Network.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.