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Avalanche Forecast

Archived

Apr 22nd, 2023–Apr 23rd, 2023

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

Regions

North Columbia, South Columbia, Esplanade, Jordan, North Selkirk, West Purcell, Badshot-Battle, Central Selkirk, Goat, Gold, Kokanee, Retallack, Valhalla, Whatshan.

Warming temperatures and forecast snow or rain will increase avalanche hazard.

Expect spring conditions at elevations up to around treeline, and solar aspects well into the alpine. Temperatures are rising which over time melts the strength out of the snow; avoid avalanche terrain if the sun pops out, during periods of heavy snow or rain, or if you observe (recent) avalanche activity.

Confidence

Low

Avalanche Summary

No new reports of avalanches on Friday.

Thursday reports were primarily Loose Wet slides due to solar triggers, a couple of size 2 wind slab or storm slabs. Also on Thursday was this report (from inside Glacier Park) showing the April Fools Crust remains a concern

Snowpack Summary

Dry, powder snow remains at higher elevations on north-facing terrain. While multiple melt-freeze crusts or moist snow are found in the snowpack on steep solar slopes and at lower elevations.

A layer of surface hoar from March 31 persists down roughly 50 to 100 cm appears to be variable in its distribution. The surface hoar may be sitting above a crust on all but true north-facing slopes. Despite a decrease in avalanche activity on this layer, avalanche professionals continue to closely monitor it. Additionally there are similar crusts dating from April 7 and April 16 higher up in the snowpack with similar characteristics and concerns.

The mid-snowpack is strong. However, the November depth hoar remains at the base of the snowpack and remains a concern in rocky, shallow, variable depth snowpack areas at treeline and above.

Weather Summary

Saturday Overnight

Cloudy with flurries. Just a trace of snow. Light southwest ridgetop winds. Treeline temperatures around -5 C. Freezing level around 1500 to 1800 m.

Sunday

Cloudy with snow. Accumulations by the end of the day around 10 cm but as high as 15 cm. Moderate southwest winds. Treeline temperatures around zero and freezing level around 2000 m.

Monday

Warm overnight temperatures with freezing level only dropping to 1500m. Overnight another 5 to 10 cm of snow by Monday morning. Wind diminishing to light. Treeline temperatures around -3 and freezing level around 2000 m.

Tuesday

A mix of sun and cloud. Nil precipitation. Wind light southwest. Around -5 C at treeline with freezing level around 2000 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.
  • Be alert to conditions that change with elevation and sun exposure.
  • Closely monitor how the new snow is bonding to the crust.
  • Be carefull around freshly wind loaded features.
  • In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.

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.

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.

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.