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Avalanche Forecast

Archived

Apr 16th, 2023–Apr 17th, 2023

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

South Rockies, St. Mary, Bull, Elkford East, Elkford West.

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.

Avoid steep south facing slopes when the sun comes out.

Expect variable snowpack conditions as we transition from winter to spring.

Confidence

Moderate

Avalanche Summary

On Friday, on the Meachen Falls & hour glass FSR a large (size 2) wet loose avalanche ran nearly full path depositing a large debris pile on the access road. This avalanche was on a north aspect and was likely trigger during the daytime warming and solar input.

On Thursday, our South Rockies field team was out in the Mear Lake area, and they saw numerous, small (size 1-1.5), naturally triggered wet loose avalanches on steep, sunny slopes at treeline and above. See their MIN (Mountain Information Network) post here for more details.

Avalanches from earlier in the week are being reported as visibility improves, and people venture into the backcountry after the storm. As expected, there appears to have been a widespread avalanche cycle, with numerous large (size 2) and some larger (size 3) avalanches. Mostly storm slabs in the alpine, and wet loose at treeline and below.

A few avalanches likely started as storm slabs in the alpine, or just below a ridge, picked up loose wet snow, kept moving over dirt in some places, and ran down well into treeline, covering lower elevation hiking trails or forest roads.

If you head out in the backcountry, let us know what you are seeing by submitting a report to the Mountain Information Network.

Snowpack Summary

Dynamic spring weather has resulted in variable snow surface conditions. A wet storm earlier in the week soaked the upper snowpack. Cold overnight temperatures have turned this moist snow into a frozen crust, except in areas where dry snow covered and insulated it.

The mid snowpack is generally settled and strong, except in areas with snow depths less than 150 cm. In these lower snow areas, the mid-pack is likely weaker and more faceted.

Below treeline, expect to find moist or refrozen surfaces, and a shrinking snowpack that is isothermal during the heat of the day.

The lower snowpack includes a layer of large, weak facets and/or depth hoar crystals.

Weather Summary

Sunday Night

Mostly cloudy. 1-5 cm of snow expected in the alpine. Freezing level at 2000 m descending to 1100 m. Moderate building to strong southwest ridgetop wind. Treeline low around 0 °C

Monday

Cloudy with afternoon clearing and sun. No new precipitation is forecast. Freezing level at 1200 m, rising to 1600 m. Moderate to Strong southwest ridgetop wind. Treeline high around 2 °C .

Tuesday

Cloudy with periods of clearing. 1-5 cm of snow expected in the alpine. Freezing level at 1500 m. Moderate easing to light southwest ridgetop wind. Treeline high around 1 °C

Wednesday

Cloudy with periods of clearing . 1-5 cm of snow expected in the alpine. Freezing level at 1600 m. Strong easing to moderate southwest ridgetop wind. Treeline high around 1 °C

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for unstable snow on specific terrain features, especially when the snow is moist or wet.
  • Even brief periods of direct sun could produce natural avalanches.
  • Be alert to conditions that change throughout the day.
  • Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.

Problems

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.