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Mountain Sledder Magazine | December 13, 2017

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Early-Season Weather Lays the Foundation for Winter Snowpack Stability

Early-Season Weather Lays the Foundation for Winter Snowpack Stability

| On 23, Oct 2017

Everyone is stoked the see the new snowfall on the mountains. The interweb is littered with pictures of fresh snow, and some are even out touring or getting a quick sled trip in. It is time to think about early-season weather and how it lays the foundation for the avalanche stability of the winter snowpack. Will it be good or bad? The weather will tell us.

 

Early-Season Weather

Lucille riding area, McBride BC on October 14, 2017. Photo: McBride Big Country Snowmobile Club

 

Early-Season Weather Lays Foundation for Winter Snowpack

The first flakes are fantastic and rightfully should be the cause of some serious stoke and itchy thumb syndrome. But they are also the beginning of a complex series of layers that make up the foundation of our winter snowpack. Are we going to get concrete for our foundation—or marbles? Only time will tell, but you should pay attention.

If we look at the last winter season, we witnessed a very early first snowfall—a substantial one at that, especially in the Cariboo Region where I spend most of my time. After this first onslaught we had rain, then drought with very cold and clear temperatures for most of December. It was the cold, early-season weather acting on the not-yet-very-deep snowpack that led to a very complex winter snowpack; one that caused me to look over my shoulder all season long. This snowpack was the cause of numerous close calls and unfortunately even fatal incidents.

Today, as I look up into the mountains surrounding Valemount, I wonder if we are being set up for a similar season? Is a weak or a strong foundation building in the high country, and how do we know?

In an ideal winter, the first snowflakes are followed by steady periods of regular precipitation. This allows for the development of a deep and well-bonded foundation for the rest of the winter’s snowpack to rest upon. While we almost always expect to see some cold days in there, what we don’t want to see are those long arctic outbreaks—days or even weeks in a row with cold, clear weather. This is great pond hockey weather, but doesn’t bode well for safe mountain riding, particularly if we get these cold spells early in the season.

 

WARNING – Geek Alert! Here’s What Happens

During cold, clear weather with no snowfall, shallow early-season snowpacks start faceting due to a strong temperature gradient. Snow is a great insulator and even a shallow snowpack insulates the ground, which leaves us with a warm ground layer and a cold snow surface temperature. This causes quick movement of water vapor through the snowpack which creates large, loose, irregular snow crystals (facets) that don’t bond well to their neighbors.

 

Early-Season Weather

Sand = rounded snow that bonds well with its neighbours. Think about how hard that sand can compact together. Ice = facets: large, loose crystals that don’t play nice and take a very long time to heal.

 

When winter decides to come back and drop a pile of snow on top of this weak foundation, we’re left with a mattress-on-top-of-marbles situation (slab on top of a weak layer) that can have serious negative consequences on our entire season’s snowpack. This is unfortunately how things played out last year in areas around Valemount and farther north (areas farther south were generally in better shape).

It looks like we are experiencing an early start to our season, which could be awesome. But, depending on the weather we experience over the next while, the foundation for our winter’s snowpack could take a turn for the worse if we experience a period of drought with cold temperatures and our early-season snow is left up there all alone.

 

Early-Season Weather

Basal facets from last winter’s snowpack.

 

Remember, the ideal situation is: once winter shows its awesomeness, it stays around and the snow continues to fall on a regular basis. If not, we end up with the scenario from last season up here in the Cariboos.

 

Watch the Early-Season Weather to Stay Abreast of What’s Happening

I guess what I am trying to get through to everyone here is—that right from the first initial snowflake that sticks to the ground, we should be paying attention. While early-season snowfalls get our blood pumping for the first rip, we can do ourselves a big favor if we try to understand a little bit of what is happening up in the mountains during the early-season. Right now, Mother Nature is laying the foundation for the rest of our season and if we can make some simple early season observations, it will help us be more aware, which leads to making better decisions when riding in the backcountry.

 

Early-Season Weather

Clemina Creek. Full failure on basal weakness.

 

On a related note, Avalanche Canada will be examining some of last year’s close calls during their outreach programs this fall, and I urge you to go attend should one come to your area.

Ride safe.

 

— Curtis

 

Curtis Pawliuk is the owner/operator of Frozen Pirate Snow Services and the general manager of the Valemount and Area Recreation Development Association.

 

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