Avalanche Forecast

Archived

Apr 9th, 2023–Apr 10th, 2023

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Jasper, Brazeau, Churchill, Cirrus-Wilson, Fryatt, Icefields, Maligne, Marmot, Miette Lake, Pyramid.

10-20mm of precipitation with strong SW wind and warm temperatures will rapidly increase the avalanche hazard overnight on Sunday.

The Icefields Parkway will be closed from 15:00-20:00h for avalanche control on Sunday. Check AB 511 for road status updates and be sure to confirm the Icefields Parkways is open before planning any travel Sunday PM- Monday.

Maligne Lake Rd will remain closed Sunday night. Check AB511 for an update Monday AM.

Confidence

Moderate

Avalanche Summary

A natural avalanche cycle is expected overnight on Sunday. This bulletin was written at 1300h to allow for avalanche control operations Sunday afternoon. No road patrol yet today.

Don't forget to post avalanche observations to the MIN.

Snowpack Summary

Rapid loading on Sunday night will create a 15-30cm thick storm slab at higher elevations which will sit over old windslab. Below tree line, incoming precipitation will fall as rain which will saturate the snowpack and make wet loose avalanches very likely in areas still holding snow. The mid-pack consists of multiple layers of dense wind effected snow, sun crusts, and facets. Depth hoar and basal facets make up the base of the snowpack.

Weather Summary

Sunday night

Periods of snow/rain.

Accumulation: 17 cm.

Alpine temperature: Low -7 °C.

Ridge wind southwest: 25 km/h gusting to 70 km/h.

Freezing 1900m.

Monday

Flurries.

Accumulation: 6 cm.

Alpine temperature: High -3 °C.

Mostly light ridge wind occasionally gusting to 45 km/h.

Freezing level: 1700 m

Tuesday

Flurries.

Accumulation: 6 cm.

Alpine temperature: Low -8 °C, High -3 °C.

Mostly light ridge wind occasionally gusting to 35 km/h.

Freezing level: 1700 m

Wednesday

Periods of snow.

5 to 10 cm.

Terrain and Travel Advice

Minimize exposure during periods of heavy loading from new snow, wind or rain.
If triggered loose wet avalanches may step down to deeper layers resulting in larger avalanches.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

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.