Toni Sittlinger Photo: Earlier in the season we were talking about depth hoar. Here is an example. Not exactly weather today for developing depth hoar, warm temperatures in the alpine with strong winds. I asked what the avalanche conditions were today and was given a very descriptive term "Pasted pockets of wind slab".  There are pockets of up to 30 cm of wind slab.  For the updated avalanche advisory click here. Advisory

For a great read and if you are interested in improving your skiing check out this book written by Ken Chaddock. Click here for more info: Improve your skiing

Yesterday was one of those amazing days.The  Kokanee Series started with a bit of fresh snow but great race conditions. Another whole centimetre fell last night with much the same for the weekend. Refer to yesterdays  post on sluffing. Will likely be more of that today.

This picture of the pump house at Horstman Creek was taken this time last year (Dec 15, 2010).

It is finally snowing, not much but enough to make the surface we so enjoy a tad softer. We received 6 cm over night at the Pig Alley weather plot. The next few days will give us snow showers to light snow. Every centimetre counts. 

You can expect to get sluffs to move today on steeper terrain. Click here: Definition of a sluff

The high pressure finally broke down yesterday allowing the first low into our area in a long time. Not much precipitation associated with the clouds but for now the high has been pushed to the south.

The grooming yesterday in Lakeside Area provided great skiing with 1 cm of new contributing to soft corduroy.  Even a centimetre can help the snow quality.

Cliff Jennings photo of Mt. Neal on the Duffy lake Road taken yesterdeay. Very large slide with a crown line that is 3 weeks old. We have been in a draught!!

If you are looking for fresh tracks Alta Lake was the place to be on the week end. The high is finally breaking down, several low pressures are approaching the coast from the north, the first one is weak but the second one could give us a bit of snow. There is a Kokanee race on Blackcomb this Thursday, last years statistics for snow on a  race day were very high. A melt freeze crust is prevalent in the alpine, will be interesting if and when we get a significant load on that layer. The avalanche danger scale is at low for all zones.

Hazard Acceptance        Risk Tolerance          Hazard Analysis             Human Factors

This picture was taken prior to all the new terminology used in the avalanche world. Risk tolerance is a term used in Finance, in the Avalanche industry it is a relatively new, commonly used term.  A hazard is defined as a "Condition, event, or circumstance that could lead to or contribute to an unplanned or undesirable event". Human factors is another term which started during World War II when pilot and machine had to become one!!  Hazard analysis is used as the first step in the process to assess risk.


This individual is skiing a south west exposure at the end of the day in a shallow snow pack above a cliff band with no companion. The photographer is a fair distance away, patrol has long gone for the day. This individuals acceptance of exposure to potential hazards is very high.

In my career I have gone to many avalanche incidents where the individual has been badly injured or killed. Ironically most of those individuals had just completed their CAA Level 1 course. The new terminology is very important and everyone should pay attention. Play hard but be safe!!!

Thanks to Jeff van Driel for this video of the propagation saw test discussed on the blog,  December 8, 2011.

Not the best place to be!! Might have been an unpleasant ride into the rocks if it were just a bit bigger. From the photo think about this skiers decision making process. Will post my thoughts tomorrow.  Perhaps some Kodak courage!

Nigel Stewart Photo: Taken up on the ice cap on Thursday December 8, 2011.

Nigel Stewart photos: Debris from the natural cycle we had November 22, 2011. Certainly tells the story about how much snow we have had in the past 16 days.

Amanda Taylor Photo: Surface Hoar from the Cerise Creek Trail. The perfect place for surface hoar development, no sun, surface temp -6 and a water source near by.

Amanda Taylor Photo: At least the conditions in the Alpine are not producing surface hoar this large. Would be nasty if and when we ever get more snow.  Possible flurries tonite, maybe 2 cm, then another 10 cm for Tuesday morning but this high pressure systems will dominate for a bit longer. Dry conditions are expected through out next week.  The snow pack has tightened up and continues too.

Spatial Variability: I tried to look up this definition in the Websters Dictionary sitting on my office bookshelf. Published in 1988... no definition!!  Today looking up the same term on Wickapedia: Spatial Variability occurs when a quantity that is measured at different spatial locations exhibits values that differ across the locations. This picture is older than my dictionary,  the slope is just above the top station of Jersey Cream chair circa 1982. The road from 7 Th Heaven to the top of JC lift is now here. Who would have thunk!  If you look up the definition on the Bilingual site of the CAA it is on page 211, scroll down, Click: Spatial Variability  There is much to learn about avalanches and travelling in the back country certainly has its risks. Digging a pit and feeling confident about the slope should be one of many considerations.  This definition is important!!

Jeff van Driel Photo and Observations. A pit displayed on the new App PitPod below:

The tests performed are the Compression test and the Propagation Saw test (PST) For an explanation of the compression test click here, scroll down: Compression test It will be listed in the glossary. The Propagation saw test is explained in this link: Propagation saw test

Persistent Weak layers: This picture shows the formation of the December 4, 2007 crust which was very active,  went to sleep, woke up went dormant and then woke up again on May 17 th and produced some very large Spring Time  Avalanches. The temperatures went to + 17 degrees on that day and there were several large events in the Whistler  Area. When this crust formed it rained to 2200 meters, the rain percolated down about 40 centimetres into the new snow and accumulated on a buried surface hoar layer. That winter was a prime example of a snow pack with a  Persistent weak Layer. Click here to see the definition of PWL. Persistent weak Layers

This result occurred 163 days after the formation of the crust.

A commonly used metaphor in the Avalanche Community is Bridging.

The picture above is taken at sunrise this morning from Coal Harbour. As I sat by the sea I could not help but reflect on this metaphor and its lack of a formal definition in any Avalanche Glossary.

I was curious about this oddity and upon my arrival back in the mountains this afternoon,  I reached out to some members of our community; an Engineer, some Back Country Skiers, and some Avalanche Technicians.

I talked to a Mountain Doctor. a  Lawyer and some Avalanche Chiefs .

Their responses varied but not by much!

A bridge in the snow pack is a vertical and horizontal element... a layer that adds a cohesive strength  above the under lying weak layers in the entire snow pack. Some snow scientist avoid the terminology................. its a touch..... intuitive.

That's another topic altogether?

Please share your thoughts as this is a very cool subject!!

Present conditions are ideal to form surface hoar. In the past few weeks there has been much discussion on buried surface hoar layers. Click on this link to understand its formation. Surface Hoar

For the latest hazard rating click here: Hazard Rating

Rob Withey Photo: Unfortunately there was condensation on the lens but Rob reported a Sz 3+ that ran last Sunday on the west aspect of the ridge on the way to the Wendy Thompson Hut. The slide ran full path, destroyed trees, turned left at the valley bottom where the skin track leads you to the hut.

For now the snow pack has tightened up and there appears to be significant bridging. The hazard rating is trending to Moderate. Click here for scale.Hazard Rating Read the description carefully. Skiers are unlikely to initiate a large avalanche but a snowmobile still has enough weight to possibly trigger the deep weak layers still present in the snowpack.

Jorli Ricker Photos of Grizzly Lake and Choclate Bowl taken on November 30, 2011. Everyone out on sleds this weekend should read the bulletins and be safe. I am sure there were many natural avalanches last week in this area but with the snow pack the way it is use caution when your out there. There is a trend for better stability but I would be wary of any lurking surprises. We still have a very complicated snowpack.