 Poster: A snowHead
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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kitenski, Great post, possible life saver.
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Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
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kitenski, +1 from me as well, great advice from Henry
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You need to Login to know who's really who.
You need to Login to know who's really who.
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Great advice. Only a lifesaver if people listen and heed the warnings. anyone who has mates heading off to the alps this week and next should show them this video and remind them of the conditions.
expect to see a big avalanche somewhere soon. unfortunately, there'll always be someone ignoring the warnings and taking the risks... only time will tell.
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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kitenski, simple, brief, clear. Thanks for posting.
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You'll need to Register first of course.
You'll need to Register first of course.
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No snowballs 
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yikes...
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German and Austrian media (TV and newspapers) have been hammering home recently that even at level one avalanches do occur and can still be fatal. Sadly 2 skier/boarders ignored this in the Allgäu last week and one paid with his life.
I can't watch the video clip as I'm in work but I have the impression that the rescues services here are getting twitchy as the next dump of snow will bring out all the powder junkies. And too many of them will have all the gear and sadly no idea.
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You'll get to see more forums and be part of the best ski club on the net.
You'll get to see more forums and be part of the best ski club on the net.
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I have to agree with Samerberg Sue.
I'm always amazed when I encounter skiers with no avy gear when they leave the resort gates and enter the back country here in Washington State. Saw several folks with no avy gear, and probably no avy training, BC training. We received 16cm of snow in the Cascades on Saturday night. Small slides and some slough. Not a serious threat. But had there been 30CM plus, then you get the powder junkies who don't think about the avy danger. Just getting first tracks. Although when avy danger goes up, they usually post patrol at the BC gates to warn folks of the dangers. Some areas are stricter than others and won't let you go through a ski area BC gate w/o proper avy gear.
I had one guy ask me on Sunday which way was south. Probably not a local, as he mistook Mt. Adams to the south for Mt. Baker to the north. I found it simply amazing that someone would not know North and South, let alone what the direction means for snow conditions.
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I posted this last Saturday...........
The good and the bad - just been speaking to a mate about the weather next week, he's a guide that lives just above La Grave - he actually likes to talk more about windsurfing than skiing etc which for him is like talking about work all the time and he said with this fresh snow on the current base it's going to be lethal.
Mates are out in Alagna this week and with Guides from tomorrow or Wed onwards depending on conditions so will be interesting to hear what they end up doing.
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snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
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I understand how that stuff would make the slope unstable come the next fall - what I am less clear about is why it might get to be OK after a few days. Will that sugary stuff have been compacted with time by the weight of the new snow on top?
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And love to help out and answer questions and of course, read each other's snow reports.
And love to help out and answer questions and of course, read each other's snow reports.
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Some lucky escapes closer to home on Saturday with 8 climbers caught up in two separate avalanches in a short space of time on CairnGorm, one casualty airlifted off the mountain by sea king to hospital. Later in the day a boarder triggered a substantial slide between Coronation Wall and the Cas Headwall, but stayed out of the slide.
The risk will be increasing with recent weather and further snow, so play safe. Worth remembering if heading into the Scottish Mountains that because the SAIS use the standard European Hazard Scale, HIGH (category 4) is the highest alert level used.
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achilles, The instability in the current snowpack (depth hoar - the sugary stuff) will not improve after a few days. It will persist, probably for the whole season (short of heavy rain or several cycles of deep melt/freeze).
That said, If you leave it a few days aftef fresh snowfall, you will still reduce your risk significantly. It is likely that there will be alot of natural activity which should "purge" slopes and probably a fair bit of human purging as well. Statistically 90% of avalanches happen within 24hrs of fresh snow so waiting is always a smart move.
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You know it makes sense.
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stevomcd, interesting. Thanks.
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Otherwise you'll just go on seeing the one name:
Otherwise you'll just go on seeing the one name:
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| stevomcd wrote: |
| achilles, The instability in the current snowpack (depth hoar - the sugary stuff) will not improve after a few days. It will persist, probably for the whole season (short of heavy rain or several cycles of deep melt/freeze). |
I was going to post a similiar question, how much of a deep melt is needed? Are we talking typica March/April spring conditions of warm days & cold nights, or does it need to be much more significant than that??
Cheers,
greg
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Poster: A snowHead
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"Hoar" is in the final stage of crystal transformation. They are formed by sublimation of water vapour in the snow pack from warm (generally ground) to cold (surface) layers. The temperature gradient provides energy for this process. Remove the energy and they don't just change back to rounds. it is like melting an ice cube, remove the heat or even freeze the water and it doesn't refreeze back into a cube. The hoar crystals need to melt than refreeze to change back into rounds. They generally persist at some layer for the whole season until the thaw. You don't get a freeze/thaw cycle on north faces until mid april.
What we are seeing at the moment isn't depth hoar as such but largely diurnal recrystallization. The clear skies are producing a strong TG in the surface of the snow transforming the snow from the top down into hoar crystals. The "sugar snow" Henry is referring to.
Last edited by Poster: A snowHead on Tue 15-02-11 11:36; edited 1 time in total
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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Kitenski - the simple answer is that it depends....
On lift accessed slopes that are frequently skied the depth hoar may already have been broken up by skier traffic.
However on quieter slopes frequented only by skiers tourers there could be much more depth-hoar.
(which is why the risk in bounds is often, but not always, lower than you will find on remote slopes that are seldom skied).
The hoar crystals slowly turn back to rounded crystals over time.
But the transformation speed depends on the temperature gradient though the snow-pack (i,e depth of the snow-pack and surface temperature).
Cold surface temperatures and shallower snow pack (i.e early season) significantly slow the time it takes depth-hoar to stabilise.
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Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
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There is extensive full depth hoar here, even close to or on tourist routes. Often it is hidden to the casual observer by a thin wind or sun crust.
Skier traffic does not always stabilise this sort of snow !!
Tracks can melt / freeze and thus produce more stable lines in the pack, but this is not always the case.
Even if it is, the stabilistaion may be insignificant compared to the weight of say 30cm of hard slab on top.
There are extensive areas here, at all gradients, and many combinations of altitude & aspect, that are full depth hoar.
Never mind fresh snowfall, there have been times where I have been concerned about the whole slope sliding off with me.
In terms of an average season (temperature / snowfall etc) hoar layers are virtualy indestructable until we enter the spring full depth melt freeze cycle.
If new snow fall comes gradualy in a series of small deposits, things may not be too bad.
If we get a major snowfall all at once, even worse with wind, it could be complete carnage out here.
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You need to Login to know who's really who.
You need to Login to know who's really who.
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| Quote: |
Worth remembering if heading into the Scottish Mountains that because the SAIS use the standard European Hazard Scale, HIGH (category 4) is the highest alert level used.
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Alan, had to check that because you had me doubting myself, but the European scale is 1 - 5 same as the US/International scales. (Confirmed on the SAIS site: http://www.sais.gov.uk/about-forecasts.asp )
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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