Avalanche Forecast

Archived

Dec 17th, 2022–Dec 18th, 2022

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Glacier.

Watch for signs of instability and have a dig to see if the persistent slab problem exists in your location.

Cold temperatures and short daylight hours could turn even a small incident into a serious emergency. Bring extra warm layers and be back well before sunset.

Confidence

Moderate

Avalanche Summary

Isolated natural sluffs and small avalanches up to size 1.5 have been observed over the past few days along the highway corridor.

Reports of small human-triggered avalanches, size 0.5 on unsupported pillows and rolls, failing on the Nov 17 layer.

Snowpack Summary

Up to 10cm now buries the Dec 16 surface hoar (up to 5mm at tree line and below) and a crust on solar aspects.

The snowpack is thin (~110cm at 2000m) and generally facetted. The Dec 5 and Nov 17 surface hoar layers are down ~40cm and ~70cm respectively and have produced sudden results in snowpack tests.

Weather Summary

An Arctic front is moving its way through the region which will drop temperatures down to -25 by Sunday evening. Winds are forecast to be light with overcast skies and light snow flurries during the day.

Clearing skies, light winds, and cold temps for Monday and Tuesday with a gradual warming trend and snow for the end of the week.

Terrain and Travel Advice

Uncertainty is best managed through conservative terrain choices at this time.
Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
Exercise caution on steep, unsupported slopes.

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.