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Archived

Avalanche Forecast

Apr 22nd, 2023–Apr 23rd, 2023
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
Below Threshold
The avalanche danger rating below treeline will be below threshold

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.

Avalanche Problems

Storm Slabs

New storm slabs are possible at high elevations. Dial back your terrain choices if you encounter more than 20 to 30 cm of new snow. Watch for this snow sitting on a slippery crust on solar aspects. Watch for wind slabs on lee features, primarily at higher elevations where dry snow persists.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Persistent Slabs

Warm temperatures and new snow may increase the sensitivity of this lingering problem. A layer buried on April 1, down roughly 50 to 100 cm from the surface, appears to be most reactive on solar tilted slopes where surface hoar may sit on a hard melt-freeze crust.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1.5 - 2.5

Deep Persistent Slabs

A weak layer of facets exists near the base of the snowpack. The likelihood of human triggering is low given the layer's depth.

Suspect terrain includes steep, shallow, and rocky terrain where the snowpack varies between thin and thick.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely

Expected Size: 2.5 - 4