Avalanche Forecast

Issued: Mar 17th, 2019 4:44PM

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

Avalanche Canada istorm, Avalanche Canada

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Sunshine and warmth may feel good to us, but it doesn't help the snow. It's a good time to step aside, watch from afar, and let the mountains shed some of their winter coat. Riding will be better, or at least safer, when it cools off in a few days.

Summary

Confidence

Moderate -

Weather Forecast

Significant warming in the forecast and next week looks very warm with freezing level above the summits. Don't let overnight cooling at low elevations (temperature inversion) fool you; very little cooling is expected at higher elevation.SUNDAY NIGHT: Clear & dry. Freezing level around 2000m. Light variable wind.MONDAY: Sunny and dry. Freezing level around 2500m, no real overnight re-freeze expected at treeline elevations. Light variable wind.TUESDAY: Just like Monday but freezing level approaching 3000m.WEDNESDAY: Just like Monday and Tuesday but freezing level exceeding 3000m.

Avalanche Summary

On Thursday, a group of riders remotely triggered a size 1.5 persistent slab from 100 metres away. See the MIN report for more details. I view this as an important piece of data when considering the effect of forecast strong sunshine and warming.Saturday's reports are of significant warming but only small loose wet avalanches. Neighbouring regions (for example Kananaskis Country) where the snowpack is thinner and weaker entered a natural avalanche cycle involving most aspects, most elevations, and most snowpack layers. IMHO this foretells the story of what's soon coming to a mountain range near you!

Snowpack Summary

Upper snowpack: Getting warm and moist during the day, maybe forming ephemeral crusts overnight. On sunny aspects there may be buried crusts serving as sliding layers. On lee slopes there may be buried hard layers of wind effected snow (buried wind slabs). There might even be some good old soft snow (powder hiding out on high elevation shadier places). Mid pack: The mid-snowpack consists of sugary faceted grains (facets) of different hardness. Two older layers of surface hoar still exist down 55-80 and down 95-150 around 1600-1900m. See Avalanche Activity section below for why this is relevant!Lower pack: Was reportedly strong in deep snowpack regions, but I have doubts in shallower areas where the long February cold weakened even the deep layers. Now add a bunch of heat and sun ... the snowpack won't be feelin' the love. Forecasting how many sunny days and warm nights it's going to take to wake up deeper layers is tough; however, I can say with confidence it's a good time to stand aside, watch from afar, let the mountains shed their coat, and come back to the game when things return to normal after the temperatures cool.

Problems

Loose Wet

An icon showing Loose Wet
Sunshine and warm temperatures will peel away layers or recent snow on sunny slopes as loose wet slides, weaken cornices, and possibly re-energize wind slabs. A key unknown is how quickly the warming and weakening will affect deeper layers.
Parking, eating lunch, and regrouping in runout zones is bad practice.Minimize exposure to overhead hazards like cornices which could easily trigger persistent slabs.Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.

Aspects: East, South East, South, South West, West.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 2.5

Persistent Slabs

An icon showing Persistent Slabs
A surface hoar layer formed in late January may be more reactive than expected, especially at lower elevations during periods of intense warming. See this MIN report for a recent remotely triggered avalanche attributed to sunshine and warming.
Remote triggering is a concern, watch out for adjacent slopes.Warming could wake up buried weak layers.Be cautious in shallow snowpack areas where triggering a deeper layer is more likely.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 3

Valid until: Mar 18th, 2019 2:00PM

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