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Avalanche Forecast

Archived

Jan 12th, 2022–Jan 13th, 2022

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

Regions

Sea To Sky.

Expect conditions to change as you move higher. Low elevations hold wet snow and higher elevations hold storm slabs that may be reactive to human triggers. Avoid large unsupported slopes - deeply buried weak layers will take time to gain strength.

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

The wet weather finally exits Thursday. Expect warm temperatures to continue Thursday before finally cooling off for the weekend.

WEDNESDAY NIGHT: Freezing levels peak at 2500m overnight with 5-10mm of rain expected. 

 

THURSDAY: The front exits leaving clearing skies and light precipitation expected in the morning - up to 5mm. Freezing levels sit around 1700 m for the day but peak at 2500m in the late evening, with light easterly winds. 

FRIDAY: Partly cloudy with isolated flurries expected. Winds return to strong southwest. Freezing levels at 1500 m. 

SATURDAY: A mix of sun and cloud with no precipitation expected. Freezing levels dip and stay below 1500m. Moderate westerly winds. 

Avalanche Summary

Naturally triggered wet avalanches were observed to size 2.5 in below treeline terrain features.

Storm slabs to size 2 were triggered naturally and by explosives or skiers at treeline and above where snow was less affected by rainfall. 

Snowpack Summary

60-90 cm of mixed precipitation has created a variety of surface snow conditions. Strong southwest winds have created deeper slabs at treeline and alpine elevations on north through east facing slopes. 

At lower elevations the precipitation mostly fell as rain creating a saturated upper snowpack sitting over a melt freeze crust that was observed to 2000 m. As temperatures cool the saturated snow will become a thick surface crust.

This recent precipitation adds to the 100+ cm of snow that has fallen since January 1, which may overly sugary faceted grains that formed during the cold spell in late December.

Around 150 to 250 cm deep, another weak layer of faceted grains may be found above a melt-freeze crust that formed in early December. The layer is most prominent between 1700 and 2100 m. Avalanches on this layer are large, but sporadic and isolated. The most likely place to trigger it would be in thin, rocky snowpack areas. The lower snowpack is well-settled and strong.

Terrain and Travel

  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Be careful as you transition into wind affected terrain.
  • 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.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.