Avalanche Forecast

Archived

Feb 1st, 2023–Feb 2nd, 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, human triggered possible.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

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

New snow and gusty winds are developing new wind slabs in open terrain features at alpine and treeline elevations. Anticipate slopes where wind slabs are developing by monitoring the wind direction and avoid areas that look wind-affected or feel dense or stiff.

Confidence

Moderate

Avalanche Summary

Several size 1 to 1.5 natural and explosive-controlled storm slabs were reported in the Lizard Range Wednesday where up to 10 cm of new snow fell Tuesday night.

Avalanche reports of small (size 1 to 1.5 ) human-triggered wind slabs continue to trickle in. This avalanche problem may continue while temperatures remain cold.

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

Snowpack Summary

10 - 15 cm of new snow being redistributed by moderate winds over various surfaces of soft faceted snow in sheltered locations and wind-affected snow in open terrain at alpine and treeline.

The mid-pack is well consolidated in the Lizard Range with a robust melt-freeze crust formed around Christmas down 70 to 90 cm deep.

Outside of the Lizard Range, snowpack depths are more shallow and faceted. In these areas, deep weak layers formed early season are still a concern, especially in steep rocky terrain features. The total snowpack depth ranges between 120 and 250 cm.

Weather Summary

Wednesday Night

Mainly cloudy, 2 to 3 cm new snow, 15 to 20 km/h southwest winds, treeline temperatures -4 ºC

Thursday

Cloudy, clearing in the afternoon, trace accumulations, 20 to 30 km/h southwest winds, treeline temperatures -4 ºC

Friday

Mainly cloudy, flurries starting overnight, 3 to 5 cm new snow, winds 20 to 30 km/h southwest. treeline temperatures -2 ºC.

Saturday

Mainly cloudy, morning flurries 3 to 5 cm new snow, winds 20 to 30 km/h southwest winds, treeline temperatures -2 ºC.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Approach lee and cross-loaded slopes with caution.
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.