Avalanche Forecast

Issued: Mar 22nd, 2019 4:43PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Deep Persistent Slabs and Loose Wet.

Avalanche Canada jsmith, Avalanche Canada

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Cooling is on the way but likely not in time to reduce the hazard on Saturday. Human triggering of deep persistent slab avalanches remains possible.

Summary

Confidence

Moderate - Track of incoming weather systems is uncertain

Weather Forecast

FRIDAY NIGHT: Clear skies / Light, westerly winds / Alpine low 0 C / Freezing level dropping to 2500 m.SATURDAY: Increasing cloudiness in afternoon / Light, easterly winds / Alpine high 1 C / Freezing level dropping to 2000 m.SUNDAY: Cloudy with flurries; 3-5 mm. / Light, easterly winds / Alpine high -3 C / Freezing level 1700 m.MONDAY: Sunny / Light, westerly winds / Alpine high 0 C / Freezing level 2000 m.

Avalanche Summary

On Thursday, there were numerous reports of skiers triggering what started as small loose wet avalanches and then gathered mass and entrained the entire snowpack to the ground running much further than expected, up to size 2. Check out this video from our South Rockies Field Team HERE.On Wednesday, an explosive control mission produced an avalanche with every shot placed (nearly 20 in total). They were loose wet avalanches on sun-exposed slopes and dry, slab avalanches on northerly aspects, up to size 2.5. Additionally, large (size 2-2.5) loose wet natural avalanches continue to occur on solar aspects.A report from our South Rockies Field Team on Tuesday in the Elk Valley described numerous natural persistent slab releases reaching size 2 (large) on southeast aspects at around 2200 m. Further to this activity, any sun-exposed snow became isothermal (slushy and cohesionless), and large whumpfs that collapsed the basal snowpack were triggered during ski touring. Check out their video HERE.

Snowpack Summary

Upper snowpack: Getting warm and moist during the day, likely forming weak crusts overnight that deteriorate during the day. On sunny aspects the upper snowpack has become increasingly isothermal (slushy and cohesionless) with successive days of warming. Mid pack: The mid-snowpack consists of weak facets (sugary snow) and layers of harder wind effected snow. Recent loose wet avalanches have been entraining additional mass by gouging into this faceted snow. These facets have also acted as a failure plane in recent slab releases.Lower pack: The strength of the lower snowpack is increasingly in question in shallower areas where the February cold was able to weaken basal (bottom of the snowpack) layers and warm temperatures are increasing the strain on these weaknesses each day. Many of the recent slab avalanches failed on these facets sitting just above the ground.

Problems

Deep Persistent Slabs

An icon showing Deep Persistent Slabs
Numerous large deep persistent slab releases have resulted from ongoing warming and strong sunshine. Deep releases are most likely to occur in thin snowpack areas in the alpine.
Sustained warming is testing deeply buried weak layers. Recognize and avoid overhead hazards.Avoid re-grouping in rocky areas with a shallow snowpack, remote triggering is still possible.Thin snowpack areas exposed to sun are likely to produce deep persistent slab releases.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 3

Loose Wet

An icon showing Loose Wet
Many recent loose wet avalanches have been entraining mass by gouging into the snowpack or triggering slabs and running much further than expected.
Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.Avoid terrain traps such as cliffs and gullies that increase the consequence of small avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2.5

Valid until: Mar 23rd, 2019 2:00PM

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