Hoar / surface frost

[Van Epps]

We are currently at the end of a severly cold / clear cycle in Wa State. These conditions persisted for roughly one week. The cycle is changing and we are getting fresh snow, looks like up to 2-3 feet in the next week. This new snow is going to be on top of the hoar deposits from the passing cycle.

My question: How do I determine if it's safe to ride up to the play area's? I don't plan on hill climbing rather boondocking / playing in the flats up high. I'm a little nervous about the multiple avy path crossings to get up to the goods.

thanks

 

[roughrider99]

alberta/Bc is also coming to the end of cold snap, i will be watching to see how much it warms up if at all and compare that to the amount of fresh snow. since snow is not crazy deep i plan on diggin a few sno pits so see what that layer will be like after this cold snap and to see how much of a bond there is between the layers.

 

[Van Epps]

Post results

 

[PalousePoo]

From what I've read and learned I am real concerned about getting out after this coming storm too. A two or three foot dump on top of that frost can't be good. Anyone have a link to the avy forecast for McCall?

 

[joeoim]

Avy Info link

Van Epps,

Call your Avalanche info center. If planning to go into dangerious country, I will call the day before, and the morning before leaving. If I think there is too much risk (I don't want to get in an avy, or have to dig for a partner) I will alter my riding to suit conditions.

Do your own assessment of snow conditions as you go along. If you haven't taken any avy training, you can find some through your local and state snowmobile club. I usually stay away from places I don't feel good about.

I don't know your area, but maybe this link will help.

www.nwac.us

Joe

 

[shoppingcart111]

We are actually doing the field training portion of our avy training this saturday in Valemount BC which will be the end of the really cold cycle and the start of the warming trend so it will be interesting to see what the snow pits show. I will post results and findings.

 

[Van Epps]

We are actually doing the field training portion of our avy training this saturday in Valemount BC which will be the end of the really cold cycle and the start of the warming trend so it will be interesting to see what the snow pits show. I will post results and findings.

It would be great if you posted your findings, I for one am very interested.

Looking at current avy conditions on local avy websites is an automatic before each ride. I was hoping to hear from guys that have been up high and witnessed first hand the amount of hoar, and have more experience correlating hoar w/instability.

We should all weigh the conditions carefully before each ride and not let adrenaline urges override our better judgment. That being said, restraint is not one of my stengths

 

[Powderhino]

Living with a Dragon..

Buried surface hoar is a problem now, and unless Mother Nature flushes it out during a natural cycle, it will remain a problem for a while.

Once it is covered, think of it as a gun that is cocked, and ready to fire. Sometimes it has a hair trigger, and doesn't take too much time of a load (YOU!) to set it off. Other times, it can stay "cocked" for a very long time, and people forget about it if they don't stay current with their avy reports.
We here in the Northwest don't "do" persistent weak layers well. We are not used to this sort of problem lingering in our snowpack. Well; it's here, and it is not going to disappear overnight unfortunately. Now we have to learn how to live with it.

How do you deal with buried surface hoar? With respect, and only go out armed with the latest avy center information to base your terrain choices on. It is okay to be conservative with your terrain choices now, in fact it is critical that you do. You can wait until the coast is clear before you head for the steeps, because as soon as this layer gets a significant load on it, it will become reactive. Stay on low-angle slopes that are not connected to steeper slopes above. Boondock the flats, or head for miserably thick tree's.

Watch the avy reports, choose conservative terrain until you are CERTAIN the hazard has flushed from the snowpack, and make sure your riding partners are armed with the same information you are, and you have all talked about it before you head out.

 

[Van Epps]

unless Mother Nature flushes it out during a natural cycle

Once its covered by say 20" or more of new snow, what "Natural cycle" will "flush it out"? I would guess unseasonable warm temps for a couple days would help bond the buried weak layer.

Thanks Powderhino / all!

 

[Powderhino]

Good question...

A natural cycle is going to be just that: Caused by Mother Nature.

Any significant additional stress could be the natural trigger.
Some examples are significant snowfall, wind transport which will not only move the snow but change its very structure and allow slabs to form.
This snow will add additional weight and stress to the snowpack. Rainfall, or rapid warming, which will do a bunch to the snowpack, none of it good. Just know this: The snowpack, just like most humans, doesn't like rapid change. Rapid change leaves little to no room for the snowpack to adjust to the additional stress, and the result can be catastrophic.

Buried surface hoar adds an additional problem to the snowpack. It can propogate slides long distances.... surprisingly long distances. Give the runout zones some serious leeway, set your track further away from traditional travel paths. This animal doesn't play nice.....

 

[Van Epps]

The lurking Dragon........beware.....Great info Rhino! thanks

What I am really trying to understand is: what will it take for this buried weak layer to eventually become stable? Is a release / slide required before stability returns to the pack?

 

[columbus]

Good question...

A natural cycle is going to be just that: Caused by Mother Nature.

Any significant additional stress could be the natural trigger.
Some examples are significant snowfall, wind transport which will not only move the snow but change its very structure and allow slabs to form.
This snow will add additional weight and stress to the snowpack. Rainfall, or rapid warming, which will do a bunch to the snowpack, none of it good. Just know this: The snowpack, just like most humans, doesn't like rapid change. Rapid change leaves little to no room for the snowpack to adjust to the additional stress, and the result can be catastrophic.

Buried surface hoar adds an additional problem to the snowpack. It can propogate slides long distances.... surprisingly long distances. Give the runout zones some serious leeway, set your track further away from traditional travel paths. This animal doesn't play nice.....

The one good thing rain/rapid warming will do to a PWL deep in the snowpack is clean it out. If we dont get a significant avy cycle that really changes our pack its gonna be a long winter. A meter of really wet snow or a bit of rain will cause most things to slide, and if followed by a bit of cold (nothing like we just had) could be the only way this PWL heals itself. Just stay the f$#@ away until it does its thing. If we just get bits of snow and nothing to really load the pack fast and cause a widespread avy cycle, this PWL will be lurking until spring and can strike when least expected.