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Avalanche Forecast

Archived

Mar 2nd, 2022–Mar 3rd, 2022

Alpine
Natural avalanches possible, human triggered probable.
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.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

Lizard-Flathead.

Stability is gradually improving but there is uncertainty about freezing levels and snowfall amounts with convective showers tomorrow. 

Test the bond of new snow on smaller features with low consequences before committing to bigger lines. 

Confidence

Moderate - Uncertainties in both the snowpack structure and the weather forecast limit our confidence.

Weather Forecast

Unstable airmass is causing uncertainty with the timing and intensity of convective showers into Friday. 

Wednesday night: Light flurries possible 5-10 cm, light southerly wind, freezing levels should drop to valley bottom, treeline lows just below zero.

Thursday: Overcast with flurries 5-15 cm, light southwest wind (could get gusty at times), freezing levels 1300-1500 m, treeline highs around -1.

Friday: Light flurries 5-10 cm should ease overnight, mostly sunny day, freezing levels will be at valley bottom at night and rise to 1300 m during the day treeline highs of -2.

Saturday: Mostly sunny, light northerly winds, treeline highs of -2.

Avalanche Summary

On Wednesday morning storm slabs were still reactive to explosives and ski cuts in the size 1-2 range. A widespread storm slab avalanche cycle with size 2-3 avalanches on a variety of aspects and elevations was reported from the region on Tuesday. Check out this recent MIN report taken from within the ski area boundary looking out of bounds towards the Mammoth Droppings.

Snowpack Summary

The Lizard Range has received over 90 mm of water from this system which has translated to about 40-60 cm of heavy, upside down type snow at treeline elevation. Convective snow/rain showers could add 10-20 cm to the snowpack on Thursday. Snow has generally been rain-soaked below 1600 m. All of this new load sits on a variety of old surfaces like sun crusts, freezing rain crusts, old wind-pressed snow or cold, weak snow crystals on shaded aspects. Moderate to strong southwest winds have likely contributed to cornice growth as well.

Storm slabs or loose wet avalanches may step down to old persistent layers such as the surface hoar layer buried at the end of January. The distribution of this layer is spotty in nature but has produced avalanches and snowpack test results in the past week, mostly in the Flathead. While it does not appear to be as widespread or reactive in the Lizard Range, it has been found in some locations. 

The lower snowpack is well consolidated, with a crust/facet layer from early-December found near the bottom of the snowpack. It is currently considered dormant but with big rain on snow events, operators will be on guard. Check out the forecaster blog for more information. 

Terrain and Travel

  • If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.
  • Use small low consequence slopes to test the bond of the new snow.
  • Be alert to conditions that change with elevation.
  • Extra caution is needed around cornices under the current conditions.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

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.