Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Jan 9th, 2014–Jan 10th, 2014

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

Regions

Sea To Sky.

Danger ratings reflect higher forecast snowfall amounts for Thursday night. Danger could be slightly lower if less snow accumulates. Be sure to make keen local observations. 

Confidence

Fair - Forecast snowfall amounts are uncertain

Weather Forecast

Synopsis: A strong frontal system will reach the South Coast late on Friday and spread heavy to very heavy precipitation, strong winds, and briefly rising freezing levels into Saturday.Friday: Heavy snow developing late in the day 15-20 cm. Very strong SW winds. The freezing level should be around 1000 m during the day, but could peak at close to 1800 m during the storm. Saturday: Continued very heavy snow in the morning, easing through the day 20-30 cm. Winds are very strong from the SW but should ease to moderate from the W-NW later in the day. The freezing level rebounds to around 1000 m. Sunday: Moderate snowfall as another weaker frontal system slides in. The freezing level should be around 500-800 m.

Avalanche Summary

A size 2 deep persistent slab avalanche was reported on Blackcomb on Wednesday. This slide was accidentally triggered by a snow cat and failed on a weak facetted layer near the ground. Check out Waynn Flann's avalanche blog for photos and more information. This avalanche highlights the potential for large and deep avalanches in many areas on the South Coast. Heavy loading Friday night and Saturday will most likely trigger full depth avalanches in some places.

Snowpack Summary

Around 10-25 cm of new snow overlies wind-pressed snow at upper elevations, surface hoar in sheltered terrain and a melt-freeze crust on previously sun-exposed slopes. Moderate to strong SW winds have probably formed new dense wind slabs in exposed lee terrain and cross-loaded features. The cold temperatures from early December have left weak faceted crystals that seem to be variably reactive. In higher elevation terrain where the snowpack was deeper, the facets likely co-exist with a crust in the mid pack. In lower elevation terrain or in shallow, rocky areas of the alpine, the facets are most likely more widespread and may exist down near the ground. Either way, the "wait 48 hours and you're good" Coastal mantra does not apply as these conditions are likely to persist for some time, and will probably become reactive with forecast snowfall.Early season riding hazards such as rocks, stumps and logs are lurking below the surface in many areas. In glaciated terrain open and poorly bridged crevasses are everywhere.

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.

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.