Avalanche Forecast

Issued: Apr 15th, 2023 4:00PM

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

Avalanche Canada jpercival, Avalanche Canada

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Remain cognizant that a weak, unpredictable layer continues to lurk near the bottom of the snowpack, avoid thin, rocky start zones and shallow areas with variable snowpack depths.

Check for signs of windslab avalanche danger like shooting cracks, especially near ridgetops and in cross loaded gullies.

Summary

Confidence

Moderate

Avalanche Summary

On Saturday a widespread natural slab avalanche cycle was observed and reported. These avalanches were very large up to (size 3) and are suspected to be storm snow than ran on a crust buried in early April.

A fatal avalanche occurred on April 15 in the Thunderwater lake riding area, just west ofthis region. The avalanche was triggered near a rocky area and was very large (size 3). Two riders were caught, one was buried approximately 2 meters deep. Despite immediate extrication and rescue response, the rider did not survive. Any additional information we have on this accident can be found in this MIN

On Friday, near Golden, a small (size 1) naturally trigger wet slab avalanche was observed on a south aspect and failed to ground on smooth shale slopes. Numerous other small (size 1) loose wet avalanches were observed on steep south aspect terrain. Additionally a few storm slab avalanches were trigger on south aspect terrain during a period of warmings and clearing.

We suspect that the weight of a human could still trigger windslab avalanches below ridgetops and in cross-loaded gully features. Also, warm temperatures and intense spring sun can quickly make loose wet avalanches likely.

On Wednesday, west of Golden, a few small, touchy windslab avalanches were reported. They were triggered remotely from 20 meters away, by skiers skinning along a ridge.

If you are getting out in the backcountry, consider making a post on the MIN (Mountain Information Network). You can share riding conditions, avalanche or snowpack observations, or even just a photo or two.

Snowpack Summary

At treeline and above, 15-30 cm of recent snow fell with moderate to strong southwest wind, forming windslabs in leeward terrain. A variety of crust, surface hoar and/or facet layers that were buried in mid March through early April may exist in the upper snowpack. None of them seem to be a current avalanche problem. Most professional operations in the forecast area are tracking their own local layer of concern to see if they become active with increasing temperatures, or more load from new rain or snow.

Below treeline, expect to find moist or refrozen surfaces, and shrinking snowpack depths.

The mid snowpack is generally settled and strong, although west of Invermere, some professional operations are still monitoring a layer of weak, feathery surface hoar crystals that was buried in mid January.

The lower snowpack includes a widespread layer of large, weak facets and/or depth hoar crystals. This weak layer has been responsible for several very large and destructive avalanches throughout the season, including one last Thursday.

Weather Summary

Saturday Night

A mix of clouds with periods of clearing. No new precipitation is forecast. Freezing level 2200 m descending to 1200 m. Moderate to strong southwest ridgetop wind. Treeline low around -2 °C

Sunday

Mostly cloudy. 1-5 cm of snow expected in the alpine. Freezing level at 1800 m, rising to 2200 m. Moderate to Strong southwest ridgetop wind. Treeline high around 2 °C

Monday

Mostly cloudy. Possible trace of snow expected. Freezing level at 1300 m overnight rising to 1600 m. Moderate south west ridgetop wind. Treeline high around 0 °C

Tuesday

Mostly sunny. 1-5 cm of snow expected. Freezing level around 1000 m overnight, rising to 1500 m. Light southwest ridgetop wind. Treeline high around 0 °C

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Use caution above cliffs and terrain traps where even small avalanches may have severe consequences.
  • Be especially cautious as you transition into wind affected terrain.
  • Be alert to conditions that change with aspect and elevation.
  • Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.

Problems

Wind Slabs

An icon showing Wind Slabs

Storm totals from earlier this week are 15-40 cm in the alpine.

Moderate to strong south and southwest winds built deeper, more reactive pockets of slab in leeward terrain.

Use extra caution around ridgecrest, small rolls, and on convex slopes. Retreat to mellower terrain if you find signs of instability like shooting cracks, whumpfs, or recent avalanches.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2.5

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

The base of the snowpack remains very weak. Avoid thin, rocky start zones and shallow areas with variable snowpack depths.

Deep persistent slab avalanches continue to be reported in this forecast area.

This is a low-probability/high-consequence avalanche problem, and managing it is very tricky.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2.5 - 4

Loose Wet

An icon showing Loose Wet

During daytime periods of warming and direct sun effect on the snow surface. Expect the loose wet avalanche problem to become increasingly sensitive to triggering.

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

Elevations: Treeline, Below Treeline.

Likelihood

Likely

Expected Size

1 - 1.5

Valid until: Apr 16th, 2023 4:00PM

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