Lizard Range and Flathead Avalanche Forecast

Issued: Mar 1st, 2021 4:00PM

Tue Mar 2nd Current Conditions
Alpine Considerable Treeline Moderate Below Treeline Moderate
Wed Mar 3rd 2 Day Outlook
Alpine Considerable Treeline Considerable Below Treeline Considerable
Thu Mar 4th 3 Day Outlook
Alpine Considerable Treeline Considerable Below Treeline Considerable

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Persistent Slabs and Wind Slabs.

There is still the potential to trigger persistent weak layers. These are producing large and consequential avalanches. A conservative mindset and patience are required.

Fresh wind slabs may be reactive to human triggers on northeast and east slopes.

Summary

Confidence

Low - Uncertainty is due to how quickly the snowpack will recover and gain strength. Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.

Weather Forecast

Tuesday: Cloudy with a trace of new snow. Ridgetop wind 20 km/hr gusting to 70 km/hr from the southwest and alpine temperatures near -4. Freezing levels 900 m.

Wednesday: A mix of sun and cloud. Ridgetop wind light from the southwest and alpine temperatures near -2. Freezing levels 2000 m.

Thursday: A mix of sun and cloud and freezing levels rising to 2000-2500 m.

Avalanche Summary

No new avalanches reported on Monday. 

On Sunday skier triggered wind slabs up to size 1 were reported. These were 10-20 cm deep and found along ridgelines and open slopes. 

Our primary avalanche problem is persistent slabs. The persistent slab is down 40-100 cm and mostly found around treelne elevations. It is likely to trigger by the weight of a skier or sledder, initiating large and consequential avalanches. Almost daily we've received reports of skier and rider-triggered persistent slab avalanches from the SoRo and Lizard forecasting regions. These avalanches have been size 2 or larger and have caught people by surprise. This problem is not healing quickly and the conditions are not easily managed. A conservative mindset and patience are crucial right now.  

New wind slabs may exist on East to Northeast aspects on Tuesday and loose-dry avalanches may spill from steeper terrain features, especially when the sun is out. 

Snowpack Summary

Strong west-southwest winds have formed reactive wind slabs on leeward slopes and solar aspects have a thin 1-3 mm sun crust. Up to 50 cm of snow sits above a variety of old interfaces that formed mid-February. These mostly include sugary facets, hard wind pressed surfaces, surface hoar in wind-sheltered locations, and sun crust on steep solar aspects. Another persistent weak layer is found down 60 to 100 cm deep and was buried late-January. This layer consists of similar weak snow crystals mentioned above and continues to be reactive by the weight of a person.

There are presently no deeper concerns.

Terrain and Travel

  • The trees are not the safe-haven they normally are at this time. Terrain at treeline is primed for human triggered avalanches.
  • Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
  • Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
  • In times of uncertainty conservative terrain choices are our best defense.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.

Problems

Persistent Slabs

An icon showing Persistent Slabs

Likelihood

Possible-Likely

Expected Size

2 - 3

Two layers of concern exist and have been reactive over the past couple of days. The upper layer being buried mid-February down 30-50 cm and has recently failed primarily on a sugary facet interface and the deeper layer of concern is found down 60-100 cm. This layer consists of surface hoar, faceted grains, and/or a melt-freeze crust. The layer has been most problematic around treeline elevations and in openings below treeline, but also reaches into the lower alpine. Avalanches are easily triggered by the weight of a person on this interface and have occurred on surprisingly shallow slope angles.

Aspects:

All aspects.

Elevations:

All elevations.

Wind Slabs

An icon showing Wind Slabs

Likelihood

Possible-Likely

Expected Size

1 - 2

West to southwest wind has formed reactive wind slabs on leeward slopes. These could be triggered by the weight of a skier or rider, especially on east-northeast aspects. 

Large looming cornices exist along ridgelines and require a wide berth from above and below, especially if they're baking in the sun.

Aspects:

North, North East, East, South East, North West.

Elevations:

Alpine, Treeline.

Valid until: Mar 2nd, 2021 4:00PM

Forecast Trend

The latest forecast danger ratings, broken down to elevation. See how an elevation is trending.