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North Rockies Avalanche Forecast - March 30, 2021

Wind slabs may be found on many aspects due to recent variable winds. Back off if you encounter whumpfing, cracking, or hollow sounds. At this time of year, even brief periods of direct sun can trigger avalanches, especially when there is a lot of fresh snow.
North Rockies Avalanche

Wind slabs may be found on many aspects due to recent variable winds. Back off if you encounter whumpfing, cracking, or hollow sounds. At this time of year, even brief periods of direct sun can trigger avalanches, especially when there is a lot of fresh snow.

Tuesday

Alpine - Considerable
Treeline - Moderate
Below treeline - Moderate

Wednesday

Alpine - Considerable
Treeline - Moderate
Below treeline - Moderate

Thursday

Alpine - Moderate
Treeline - Moderate
Below treeline - Moderate

Avalanche Summary

With plenty of new snow to move around and moderate to strong winds in the forecast, wind slabs are likely to be found and may be reactive to human triggers.

There have only been a few avalanche reports in recent days, though with up to 40 cm of new snow on the weekend, it is very likely that a natural avalanche cycle occurred, especially in the areas that saw the highest snowfall amounts.

On Sunday we received second-hand information about a size 2-2.5 (estimated) rider-triggered avalanche in the Hasler area.

On Saturday there was a report outlining natural avalanche activity in Evanoff Provincial Park. 

On Thursday, there were numerous reports of size 2-2.5 explosive triggered avalanches in the Table River Valley.

A widespread natural avalanche cycle with avalanches up to size 3 was reported last Wednesday.

Snowpack Summary

The North Rockies received anywhere from 10-40 cm of new snow over the weekend with strong south to southwest winds. Winds became strong out of the northwest on Monday, likely resulting in variable wind loading patterns, with wind slabs possible on many aspects.

The new snow has buried melt freeze crusts at lower elevations and on solar aspects and otherwise adds to 30 to 50+ cm of settling dry snow from last week. The new snow may be particularly reactive where sits on a crust.

Cornices have also become very large along ridgelines and always have the possibility of failing naturally or from the weight of a human. Direct sun and rising temperatures can significantly weaken cornices.

A weak layer of facets buried in mid-February may now be found around 120 to 150 cm deep, or shallower in the east of the region and in thin snowpack areas. The most likely place to trigger this layer is where the snowpack is shallow in alpine terrain. Large loads, such a cornice falls or multiple sleds on the same slope often trigger slopes that a single rider couldn't trigger on their own.

Weather Forecast

TUESDAY: Mainly cloudy with flurries / strong northwest wind / alpine high temperature near -5.

WEDNESDAY: A mix of sun and cloud / strong southwest wind / alpine high temperature near -2 / freezing level 1700 m.

THURSDAY: Cloudy with flurries, 5 cm / strong southwest wind / alpine high temperature near -2 / freezing level 1700 m.

Travel and Terrain Advice

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Stay off recently wind loaded slopes until they have had a chance to stabilize.
  • Be aware of highly variable recent wind loading patterns.
  • Avoid exposure to steep, sun exposed slopes, especially when the solar radiation is strong.
  • Be aware of the potential for large avalanches due to the presence of a persistent slab.