Avalanche Forecast

Archived

Feb 10th, 2023–Feb 11th, 2023

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

Lizard-Flathead, South Rockies, Flathead, Lizard, Bull, Elkford East, Elkford West.

Pay attention to the direction of the wind as you travel through wind exposed areas – there is still snow available to build wind slabs.

Confidence

Moderate

Avalanche Summary

On Wednesday there was a report of a size 2 natural windslab avalanche on a west aspect at 1800m east of Elkford. It is outlined in this MIN report here.

On Tuesday and Wednesday in the Lizard range there were reports of several explosives controlled storm slab avalanches to size 2.5 in the alpine on northerly and easterly aspects. There also reports of a few skier triggered storm snow avalanches to size 1 and 1.5.

Please continue to share any observations or photos on the Mountain Information Network.

Snowpack Summary

10-30cm of new snow from early this week has being redistributed into lee terrain in wind exposed areas at upper elevations. This overlies previous wind slabs, or a melt-freeze crust below 1900 m.

In the Lizard range specifically, the mid-pack is consolidated with a supportive 10-20cm thick frozen crust buried 80 to 100 cm.

In the Elk Valley and Flathead areas, deeply buried weak layers formed early season are slowly gaining strength but are still a concern, especially in steep rocky terrain features where the snowpack is thin.

Weather Summary

Friday Night

Mainly cloudy with isolated flurries, accumulation 1-3cm. Moderate west ridgetop wind. Treeline temperature around -6 ºC.

Saturday

Mainly cloudy with sunny periods. Light to moderate west and southwest ridgetop wind. Treeline temperature around -3 ºC. Freezing level rising to 1300m.

Sunday

Mostly cloudy. Light west ridgetop wind. Treeline temperature around -2 °C. Freezing level around 1500m.

Monday

Mainly cloudy with flurries. Moderate southwest ridgetop wind. Treeline temperature around -2 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Be especially cautious as you transition into wind affected terrain.
Pay attention to cornices and give them a wide berth when traveling on or below ridges.
Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.

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.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.