Avalanche Forecast
South Columbia
New snow is on the way which is GREAT, but a buried weak layer down 30 to 90 cm continues to produce both natural and human triggered avalanches. The message may be getting repetitive, but conservative terrain selection remains a must.
Avalanche Problem 1: Persistent Slabs
What Elevation?
Which Slopes?
Chances of Avalanches?
Expected Size?
Travel and Terrain Advice
- Conservative terrain selection remains prudent in this time of change.
- Numerous large avalanches have run on these layers in well supported, treed terrain.
- Caution with open slopes and convex rolls below treeline where buried surface hoar may be preserved.
Avalanche Problem 2: Storm Slabs
What Elevation?
Which Slopes?
Chances of Avalanches?
Expected Size?
A few cm of snow Tuesday night and then a few more cm late Wednesday will rest on a potpourri of old surfaces including crust and feathery surface hoar. Storm slabs should be small Wednesday, but by Thursday they could pack more of a punch.
Travel and Terrain Advice
- Watch for rapidly changing conditions during periods of heavy loading from new snow, wind, or rain.
- Sluffs will be easy to trigger in steep terrain that is sheltered from the wind
- Carefully monitor the bond between the new snow and old surface, touchy slabs may form quickly.
Avalanche Summary
On Monday warm temperatures and direct solar induced natural avalanches to size 3.0 on solar aspects, the largest ran on a steep south/southwest face in the alpine. Human triggered avalanches to size 1.5 were reported on north and northeast facing terrain above 2000 m, likely running on the early January interface.
On Sunday there was a widespread natural avalanche cycle to size 3.5. These very large avalanches were running on southwest, south and southeast facing alpine features and were triggered by a combination of above freezing alpine temperatures and direct solar input. Three size 2.5 avalanches likely failing on the early January interface were reported to have ran naturally on a southwest facing slope from 1900 m down to 450 m, covering a snowmobile access road south of Revelstoke. Another remotely triggered size 2.0 avalanche was reported on a northeast facing feature at 2050 m that failed on the early January weak layer.
Snowpack Summary
Spotty freezing rain Tuesday may have left a slight "glaze" on the surface which adds to the crust that is being widely reported from many locations, high elevation north is likely one of the few crust-free zones. Fresh surface hoar 3 to 10 mm in size has been reported to at least 2100 m, possibly higher. We can probably expect a touchy storm slab to form on this interface as storm totals exceed 10 cm.
There are two active Persistent Weak Layers (PWL) that we are monitoring.
The first PWL is known as the early January interface, it is 30 to 90 cm below the surface. It is composed of surface hoar on sheltered slopes as well as sun crust on steep solar aspects and is present at all elevation bands. Recent snowpack tests have shown sudden results with moderate loads.
The second PWL is the mid-December facet/surface hoar/crust combination that is now buried 70 to 150 cm deep and is most problematic at and below treeline. This interface is not thought to be present in the alpine.
The November rain crust down 125 to 200 cm is thought to have gone dormant for the time being.
Weather Forecast
On Wednesday morning a strong winter storm will arrive on the BC coast. Rather warm air and precipitation is expected to spread into the interior Wednesday afternoon resulting in snowfall through Thursday evening. The freezing level should fall back towards valley bottom Thursday night. Friday and Saturday look cool and calm with another system set to move into the interior on Sunday.
WEDNESDAY: Broken cloud cover, freezing level rising to around 900 m, moderate south/southwest wind, 2 to 6 cm of snow possible in the afternoon, 10 to 20 cm possible Wednesday night.
THURSDAY: Broken cloud cover, freezing level around 1500 m, moderate to strong southwest wind, 1 to 5 cm of snow possible.
FRIDAY: Scattered cloud cover, freezing level beginning at valley bottom rising to around 1200 m in the afternoon, light west/southwest wind, trace of snow possible.
Avalanche Forecasts in your Inbox
Avalanche Canada has switched to an RSS feed for its daily forecasts. This is a much more flexible method that allows automatic delivery to your email inbox, or to an RSS reader of your choice.
What are RSS feeds?
RSS (Really Simple Syndication) is a popular standardized file format allowing up-to-date delivery of web-based content. RSS feeds enable you to receive content updates from websites, delivered to your email through an RSS aggregator (such as blogtrottr.com) or viewed through applications called RSS readers (such as feedly.com).
Set up an RSS feed for your email:
Select a RSS aggregator
- South Columbia URL:
http://www.avalanche.ca/api/forecasts/south-columbia.rss - Copy the url and paste it into the appropriate field of your RSS aggregator.
- Fill in your email address.
- Voila! Watch the Avalanche Canada forecast roll into your inbox.
Forecast Disclaimer
Avalanche Canada's Public Avalanche Bulletin, and other information and services provided by Avalanche Canada, are intended for personal and recreational purposes only.
**THIS INFORMATION IS PROVIDED "AS IS" AND IN NO EVENT SHALL THE PROVIDERS BE LIABLE FOR ANY DAMAGES, INCLUDING, WITHOUT LIMITATION, DAMAGES RESULTING FROM DISCOMFORT, INJURY, OR DEATH, CLAIMS BY THIRD PARTIES OR FOR OTHER SIMILAR COSTS, OR ANY SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, ARISING OUT OF THE USE OF THE INFORMATION.**
The user acknowledges that it is impossible to accurately predict natural events such as avalanches in every instance, and uses the data in this bulletin with this always foremost in mind. The accuracy or reliability of the data is not guaranteed or warranted in any way and the Providers disclaim liability of any kind whatsoever, including, without limitation, liability for quality, performance, merchantability and fitness for a particular purpose arising out of the use, or inability to use the data.
As new snow begins to fall we can't forget about the persistent weak layers lurking in our snowpack that continue to produce large human triggered avalanches. Keep the terrain choices reigned in as the snowpack adjusts to the new load.