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Avalanche Forecast

Mar 20th, 2019–Mar 21st, 2019
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
4: High
The avalanche danger rating below treeline will be high
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
3: Considerable
The avalanche danger rating below treeline will be considerable
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
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: North Columbia.

The hot and sunny weather persists on Thursday, which will likely continue the natural avalanche cycle. The danger will be the highest when the day heats up, so make sure you are completely out of avalanche terrain, with no overhead exposure.

Confidence

High -

Weather Forecast

WEDNESDAY NIGHT: Clear skies, light southeast wind, alpine temperature 6 C, freezing level 3300 m.THURSDAY: Clear skies, light southeast wind, alpine temperature 5 C, freezing level 3000 m.FRIDAY: Partly cloudy skies, light east wind, alpine temperature 4 C, freezing level 2800 m.SATURDAY: Cloudy with light rain and snow in the high alpine, accumulation 2 to 5 mm, light east wind, alpine temperature 0 C, freezing level 2200 m.

Avalanche Summary

The wet loose avalanche cycle continued on Tuesday, producing small to large (size 1 to 3) avalanches on southeast to southwest aspects.  The avalanches were at all elevations. There were also a large slab avalanche that released on a south aspect at 2400 m, possibly releasing on the weak layer described in the snowpack summary.This avalanche cycle is expected to continue, as temperatures remain exceptionally warm and the sun shines strong.

Snowpack Summary

The warm air and sunny skies have produced moist snow to ridge top on all aspects. The upper 40 to 60 cm of snow may slide easily during the day, either as loose wet snow or as a cohesive slab, as it sits over weak faceted grains or a melt-freeze crust on sun-exposed slopes. The moist snow may freeze into a melt-freeze crust overnight.Below treeline, a weak layer of faceted grains and/or feathery surface hoar crystals buried in mid-January may be found around 70 to 120 cm deep. Although this layer has been dormant for a few weeks, the current warm conditions may awaken this layer. Steep cutblocks and large open glades at lower elevations are the most likely places to trigger this layer.The lower snowpack is generally consolidated and strong. The exception is around thin, rocky areas in the alpine, where the snowpack is composed of faceted snow. The warm air and sunny skies could trigger very large avalanches that could run to the valley bottom.

Avalanche Problems

Loose Wet

The upper snowpack is destabilizing in the day with hot and sunny weather, producing large avalanches. The most problematic time is with maximum warming during afternoon hours. Best to avoid avalanche terrain on or beneath southerly aspects.
Constantly look up: stay well-away from overhead exposure, as avalanches could run full-path.Cornices are large and looming and could trigger avalanches on slopes below them.Avoid avalanche terrain during the afternoon heat, particularly on sun-exposed slopes.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Very Likely

Expected Size: 1 - 2.5

Persistent Slabs

A slab of snow is poorly bonded to weak, sugary faceted snow or a melt-freeze crust. The warm temperature and strong sun has increased the likelihood of triggering a slab avalanche by humans, cornices, and naturally.
Avoid corniced ridges; they are weak and could trigger persistent slab avalanches.Avalanches could reach valley bottom; avoid all overhead exposure.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1.5 - 3