/ Avalanche conditions on Ben Nevis Sunday 17/3/13

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Roberttaylor - on 18 Mar 2013
Hello,

What did people think of the avalanche risk on Ben Nevis on Sunday the 17th of this month? I was on the hill along with lots of other folk and observed the following:

Lots of powder
Biiig cornices
Powder at lower altitude, just above the CiC was 'fracturing' (don't know if that's the right word, when it cracks under your feet) but this wasn't happening higher up (colder?)
Powder at steeper angles was coming away in blocks (on Douglas gap W gully)

I changed my route from Douglas gully W to SW ridge on the Douglas Boulder after a brief and unpleasant wading session. Then we finished up TR, which seemed fine in terms of avalanche risk i.e. no huge long snow slope at the very end.

Who else was out and what did you think? Was SAIS accurate? I am trying to improve my reading of conditions.

Robert
simondgee - on 18 Mar 2013
In reply to Roberttaylor:
hope you had a great day... we were enjoying stellar winteriness 250 miles further south so cant comment specifically but powder does not do those kind of things...it is funnily enough powdery. I suspect you were experiencing windslab or crust of freeze/thaw modified snow.
Did you assess the snow pack say with a 'hasty pit' or compression column and work anything out for your specifics? as any SAIS/conditions report is a guide and localised you can get huge differences.
Roberttaylor - on 18 Mar 2013
In reply to simondgee: You are quite right, windslab is what I was looking at. I guess I've just been calling it powder.

All the assessing I did was visual and based on how it behaved beneath my boots.

R
simondgee - on 18 Mar 2013
In reply to Roberttaylor:
It would be really good (potentially life saving) to pickup some basics on snow pack assessment...it can all seem a bit overpowering and ski/snowboard centric but abit of reading/video watching and some practise is worth every second 10 x over. Essentials learning a bit about snow pack, and handy little assessment skills like hasty pit, after that rutschbloc, compression columns tests and shear tests is quite good fun and useful...keep yerslef safe :-)
AdrianC - on 18 Mar 2013
In reply to Roberttaylor: I wasn't on the Ben but was in Glencoe. Observed up to about 30cms of new snow which was poorly bonded to the old snow beneath. I was pretty wary about anything lee & steep & thought the danger rating of considerable was right. Thought at the time that I wouldn't have been surprised to read of people kicking off slides but haven't seen any reports today.
Scott_vzr on 18 Mar 2013
There was lots of powder on Glencoe, I was sliding down it on my Snowboard !

On unpisted drifts there was some fractures of the newer snow breaking on top of the older snow, a weak bond.

As Glencoe Ski area has some pisting done, it's hard to tell #real# snow conditons but it would have been High Risk as far as I can make out.
Scott_vzr on 18 Mar 2013
SAIS Lochaber had three different failures at the test site.

http://www.sais.gov.uk/profile_flash.asp?id=11569
Chad123 - on 18 Mar 2013
In reply to Roberttaylor:

we did a lot of wading up powder yesterday en route to the Orion face, and although friend voiced his concerns about the snowpack, it seemed to me like fresh powder on a firm base with no obvious layers or warning signs. the excellent bum slide down number 4 from just below the cornice confirmed the observations. I think the sais forecast was spot on. From shear test videos in glencoe, looked worse there....
Michael Gordon - on 18 Mar 2013
In reply to Chad123:

I'd agree with that though we still tried to keep travel in easy gullies to a minimum.
Exile - on 18 Mar 2013
In reply to Roberttaylor:

I was on the Ben. We went into Observatory Gully, initially to see if we could do Sickle, but we found the slope below it to be a four inch slab with a six inch soft layer under that, on the old hard packed base. As a result we decided on not getting on the routes up near Sickle, or those in the Orion area, and ended up on Great Chimney as we could get there reasonably safely because of the difference in aspect of the slopes below it. I wouldn't have gone any further up observatory though.

In general it felt like a day when it was easy to push it a little to far in a 'it's ok so far, lets just have a look' sort of way, and end up in trouble.

Roberttaylor - on 18 Mar 2013
In reply to Roberttaylor: Chad and Michael, cheers, that is pretty well what I thought.

Roberttaylor - on 18 Mar 2013
In reply to simondgee: This is pretty much what I have been learning recently. I decided to ask on UKC to see what others thought and see whether it tallied with my own opinions.
Patrick Roman - on 19 Mar 2013
In reply to Roberttaylor:

I broke trail all the way into Coire Leis on Sunday (I wanted a workout for my legs...) and climbed on The Little Brenva Face (east facing). The snow was mostly knee deep (occasionally waist deep) but generally stable. Any poorly bonded windslab that did exist was localised and easy to skirt. Number Four Gully and Coire na Ciste felt less stable. The SAIS observations appear to be spot on:
http://www.sais.gov.uk/page_Lochaber_seven_day.asp

For those interested, routes on The Little Brenva Face are in good condition at the moment with plenty of ice around. If you're not familiar with the face, though, wait until the visibility is good as the routes can be difficult to locate.
Fultonius - on 19 Mar 2013
In reply to Roberttaylor: Apologies if I'm telling you something you a;ready know but it's worth reiterating - Cat 3 is "Considerable". While it is is the the middle of the 1-5 scale it does not mean "Average".

Also, the vast majority of people caught in avalanches get caught on a Category 3 day.
Roberttaylor - on 19 Mar 2013
In reply to Patrick Roman: Thanks Patrick, good to know. I have next weekend free...
Roberttaylor - on 19 Mar 2013
In reply to Fultonius: That makes sense I guess, fewer folk will go out in 4/5.

Looks like I was a bit wrong in what I thought given the SAIS observed avalanche risk for 17th.
CurlyStevo - on 19 Mar 2013
In reply to Fultonius:
I think one of the problems is many folk consider Cat 3 to be normal amount of risk and don't try and plan around it by climbing on lower category aspects at other venues and / or completely avoiding the bigger risks like gullys and slopes in category 3 aspects. Conversely on Cat 4 days many folk seem to stay at home even when there are often aspects with much lower risk on these days.
RKernan - on 19 Mar 2013
In reply to Roberttaylor:
Was up on saturday when all that snow fell. Broke trail up observatory gully to Smith's route in calf deep snow, which was thigh/waist deep by the time we were descending from our epic 10 hours later. I was a bit worried about the hazard on the descent but tbh put it ou of my mind as we had no real choice by that stage.
Milesy - on 19 Mar 2013
Personally on some of the aspects discussed on The Ben in those conditions I think a some people were making poor judgements, especially in regards to charging up to the higher ends of Observatory Gully and the Ciste. This what has been discussed as "getting away with it" in the previous avalanche reports. I have had some really good days on bomber neve recently and that is the conditions I love and choose to climb in. I do not take chances on slab, and on deep fresh powder. My risk assessment, my choice.
Tim Chappell - on 19 Mar 2013
In reply to RKernan:

blah blah blah inexperienced punter blah blah blah life in your hands blah blah blah other people's safety too blah blah blah whereas I know everything blah blah blah

;-)
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MG - on 19 Mar 2013
In reply to Milesy:
I think a some people were making poor judgements, especially in regards to charging up to the higher ends of Observatory Gully and the Ciste.

How is being at the bottom of them safer? Any avalanche will be going full throttle by the time it gets towards the lower reaches.
RKernan - on 19 Mar 2013
In reply to Tim Chappell:

Touché, if anything my experience demonstrated that I'm the punter! Always good to be cut down to size occasionally.

I have on more than one occasion found myself in unexpected and dangerous snow conditions where the only option was to grin and bear it - sometimes there's things you jsut can't control for. Bit different to deliberately climbing directly underneath someone else ;)

Tim Chappell - on 19 Mar 2013
In reply to RKernan:


No no no--I wasn't cutting you down, I was preemptively mocking those who might.

I once soloed my way up Winter Corrie on Driesh. As I topped out something went whump and a crack opened up right across the snow-slab I'd just climbed up, all the way into the cornice I was currently engaged in. I don't think I breathed again till I was lying in the grass at the top.

If any winter climbers tell you they've never been in that sort of corner, they're lying.
Milesy - on 19 Mar 2013
In reply to MG:

Deeper snow?
Greater tension in unstable snow?
Longer run out?

There are routes you can get to that doesnt involve going right up into the deepest and broadest slopes. When conditions are iffy even the guides will be about the Douglas Boulder and ridges, not plowing up into the depths of the corries.
RKernan - on 19 Mar 2013
In reply to Tim Chappell:

Ah fair enough, people have been cut to pieces for a lot less on here in recent times!

You're absolutely right - it's easy to get yourself into a corner while winter climbing and even easier than that to rush to judgment. There are a lot of variables, and they can change very, very quickly.
Exile - on 19 Mar 2013
In reply to MG:
> (In reply to Milesy)

> How is being at the bottom of them safer? Any avalanche will be going full throttle by the time it gets towards the lower reaches.

Because many avalanches are victim triggered - in many instances there won't be an avalanche to 'be going full throttle' if the slope hasn't been weighted by a climber. As a result standing under a slope is far safer than being on it, (assuming you're not standing on it watching somebody go up it!)

MG - on 19 Mar 2013
In reply to Milesy: Yes I know all that. My point was that if an avalanche occurs, you are not really any safer at the bottom of a gully than at the top, and quite possibly worse off. I suppose you are less likely to trigger one at the bottom but given how crowded the Ben is, it is probable that there will be parties above you anyway.
Milesy - on 19 Mar 2013
In reply to MG:
> (In reply to Milesy) Yes I know all that. My point was that if an avalanche occurs, you are not really any safer at the bottom of a gully than at the top, and quite possibly worse off.

We are talking about being in the terrain which is likely to avalanche. You are more likely to trigger in avalanche in loading conditions high up in Observatory or Ciste than you are picking your way up to the Douglas Boulder. Why do you think the SAIS compass rose increases in danger with greater altitude? 900m might be marginal but 1200m might be horrifically dangerous.
MG - on 19 Mar 2013
In reply to Milesy: I think you are still missing my point. Where do you see heaps of avalanche debris? At the bottoms of gullies or at the tops? If it is not you who triggers something, I don't see the bottoms of gullies are any safer.
Milesy - on 19 Mar 2013
In reply to MG:

Easy compromise.

1. Don't be high up in avalanche terrain where you might trigger one.
2. Don't be low down in avalanche terrain if there are people higher up that might trigger one on you.


Tim Chappell - on 19 Mar 2013
In reply to Milesy:


So...er...be in the middle of the avalanche terrain?

<scratches head>

:-)
RKernan - on 19 Mar 2013
In reply to Tim Chappell:

Be in the pub
Tim Chappell - on 19 Mar 2013
In reply to RKernan:

Or on the Sunnyside Poma :-)
sebrider - on 19 Mar 2013
In reply to Roberttaylor: On Sun lower down by the Douglas boulder I had figured a 3 ish avalanche risk. The two main layers were bonded okay and the result of the two recent snowfalls. Higher up at the toe of Observatory ridge things were rather different. Where I dug my pit was a layer of very sugary depth hoar under the two new layers - the risk going by that was up to 4 or 5 there. We decided to turn back and went with Vanishing gully. That was just my take on it.
Nath93 - on 19 Mar 2013
In reply to Roberttaylor: Did a route on Sgurr a Bhasteir in the Cuillin at the weekend and planned on descending Broad Gully (which was fine in the lower reaches as we had used it to reach our route) and first step into the top of the gully told us it was high risk. Not even worth it, descended NE Ridge instead which was much more pleasant.
Jamie B - on 19 Mar 2013
In reply to Roberttaylor:

Sounds like you made good decisions. Regardless of how easily the snowpack was shearing, whether it was category 3 or 4, or whatever localised info a pit might give you, we have an awful lot of fresh snow sitting around on moderate angle slopes. This should *always* get the alarm bells ringing.

Or to put it another way, if there's any doubt, there's no doubt. Add a 20% (at least) margin for error to all your observations. So your 70% certainty that you are safe may only be 50/50. And if you think things are 50/50 it may be that you have a 70% chance of getting wiped - not good odds.

I'm increasingly thinking that if you're digging pits you shouldn't be there, the existence of doubt is clear and present. I tend to view them as an educational tool now, rather than any sort of magic bullet. Heuristic trap anyone?
mrchewy - on 19 Mar 2013
In reply to Jamie B: Aye - I enjoyed digging pits on my first winter skills but to be honest, I wouldn't be on a slope I though I needed to check. I'm not that desperate to want to get to a certain route. It may be different if you've been benighted in a storm and are coming down next day.
sebrider - on 20 Mar 2013
In reply to Jamie B:
> (In reply to Roberttaylor)
I'm increasingly thinking that if you're digging pits you shouldn't be there, the existence of doubt is clear and present.

Maybe yes if you are climbing, but if I'm digging pits it is probably good for skiing and cat 3 snow for skiing is a goer...for me anyway, with full ARVA equipment and skiing in the right places etc.!

For those that thought the snow pack was okay on Sun...there was an avalanche reported by SAIS on the NE of Anoach mor...skier triggered.


simondgee - on 20 Mar 2013
In reply to Jamie B:
Sorry but I disagree. Having your skills to assess the snowpack on representative aspects helps you develop a clearer and relevant understanding of what has gone on and what is going on with snow. I treat all avalanche information with a great deal of respect but a forecast of 'X' for an area as big as Glencoe or Lochaber is guide ...as you know you can get spontaneously triggering avalanches on 3 days and have low risk slopes on high risk days. Only by assessing the conditions myself am I able to take responsibility and make the right decisions for myself, whoever I am with whether it be climbing partner, fellow team members or causalities the other side of slope. The principal though...you are not looking for signs of stability...you are looking for the instability 'flags' and giving them huge credence.
BruceM - on 20 Mar 2013
In reply to Roberttaylor:

What sort of pits are people digging when they say pits? I thought in general, after recent discussions, that "climbers" weren't carrying shovels and other rescue stuff in their kit. You can't dig a very good pit with an axe. Interested to know. Cheers.
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ccmm on 20 Mar 2013 - 194.82.141.222 whois?
In reply to BruceM:

You can dig a hasty pit with your adze in about 30 seconds and analyze the resusts i.e. sheer test in about a minute. You may be confusing a pit with a walking rutschblock test. The latter is much easier with a shovel.

I agree with Jamie that digging pits and excavating blocks is good for folk to build up knowledge in an educational capacity - less useful in telling you anything about the surrounding area. There have been numerous examples of test pits giving wildly varying data in a small geographical area.
sebrider - on 20 Mar 2013
In reply to BruceM:
> (In reply to Roberttaylor)
>
> What sort of pits are people digging when they say pits?

I just use my adze to dig away a free standing block about 1m square in an area that will be representative of the area I will be in; it's not a pit as such. On sun I dug to just under the surface of old neve (I assumed that under that was not going be the issue). All four sides are clear and the front is cleared (down slope) so you can see layers etc. If it slides as you are digging you definitely should not be there! Once dug I look for soft spots, grouple any other features in the layers. They may not be obvious though. On Sun on the Ben ice balls/grouple was pouring out of one of the layers...not good!

Then I tap the back gently and systematically with both open palms trying to tease any layers away. If some thing gives at this stage it is an unstable snow pack and still high risk. If nothing moves I tap the top of the block with both open palms. On sun I got to this stage, the block broke up revealing 2 layers, which were moderately bonded...had the grouple layer not been there I would have made this a cat 3.

If no layers revealed when the block breaks the snow pack may be okay, cat 1-2.

There are many ways of doing it, this is not the best or text book way but it is quick and tells me at least something of what is going on...at that particular point. How good it is is a lot down to your interpretation.

I use them a lot as they give me a rough idea of the snowpack stability .
sebrider - on 20 Mar 2013
In reply to Craig Mc:
> (In reply to BruceM)
> I agree with Jamie that digging pits and excavating blocks is good for folk to build up knowledge in an educational capacity - less useful in telling you anything about the surrounding area. There have been numerous examples of test pits giving wildly varying data in a small geographical area.

A good point.
Blinder - on 20 Mar 2013
In reply to Fultonius: Agree but even more sobbering this year in Switzerland this season the majaority of fatalities have been on 'Cat 2' or lower days days.

http://www.slf.ch/praevention/lawinenunfaelle/unfaelle_aktuell/index_DE
Milesy - on 20 Mar 2013
I have seen people digging pits lower down, but not higher up. I will refer to one particular instance 2 years ago where someone dug a pit at about half way between the coire floor and the foot of Mess of pottage, judged it to be safe and then ploughed their way up Jacob's Ladder without digging any further pits.

In other situations is pit digging as widespread as people claim it to be? I have seen pits in locations such as SCNL, Coire na ciste, and in the majority of these cases they are always low down, and grouped together in what looks to me like winter skills courses. How often do you see them further up the coires or at the base of snow gullies?

I don't dispute the posters on here who say they dig pits, but in the wider community while occasionally I see someone digging one (again normally low down), I certainly haven't seen them getting done en-masse, or doing them frequently while getting higher, particularly on days where the coires are heaving like Glasgow City Centre. Percieved safety in numbers?
ccmm on 20 Mar 2013 - 194.82.141.222 whois?
In reply to Milesy:
> Percieved safety in numbers?

Classic heuristic trap.

This has been posted elsewhere but it's pertinent to this thread: http://www.snowpit.com/articles/traps%20reprint.pdf
Milesy - on 20 Mar 2013
In reply to Craig Mc:
> (In reply to Milesy)
> [...]
>
> Classic heuristic trap.
>
> This has been posted elsewhere but it's pertinent to this thread: http://www.snowpit.com/articles/traps%20reprint.pdf

That looks like a really good read thanks. Shoving it on my iPad.

Even without people about, I wonder how many people would see safety in seeing existing footprints postholing to a route?
MG - on 20 Mar 2013
In reply to Milesy: Out of curiosity how many pits do you dig on a day, and how long do you spend on each one?
Milesy - on 20 Mar 2013
Every day I have chosen to go out this year has been on bomber neve, so I haven't needed to dig any pits, and I have decided I quite like this type of climbing and conditions.
drmarten on 20 Mar 2013
In reply to Milesy:
> Every day I have chosen to go out this year has been on bomber neve, so I haven't needed to dig any pits, and I have decided I quite like this type of climbing and conditions.

How many climbing days are you talking about?
Milesy - on 20 Mar 2013
Why does that matter? I choose to climb when I like the conditions. If I dont like the conditions I do something else. The number of climbs I get done is proportional to when I like the conditions. That is my way of assessing risk and that is my informed choice to make.
MG - on 20 Mar 2013
In reply to Milesy:
> Why does that matter? I choose to climb when I like the conditions.


I don't quite follow. You say you don't see many people digging pits but then say you don't do so yourself. If you don't, why do you expect other people to?

Milesy - on 20 Mar 2013
In reply to MG:

Because this year I have made the decision to climb when there is good neve. As demonstrated in this topic, other people do not. And I never said I expected people to dig pits. I am merely staying that in past years when I went out in Cat3 conditions I rarely seen anyone pit digging, or when they did they dug them lower down before heading up higher into potentially more unstable conditions.
drmarten on 20 Mar 2013
In reply to Milesy:
> Why does that matter?

It matters becaue if waiting for bomber neve means that winter climbing is only available on a handful of days, then it's very restrictive.
Milesy - on 20 Mar 2013
In reply to drmarten:

You are completely right, but obviously many days you can get good neve on one aspect where as other aspects are loaded, or good neve in the west of the country and loading on the east of the country, and vice versa.

To pick an example actually one day a few months ago while in Sneachda, our party chose like a few others on this Cat4 day to go to the Fiacill buttress. That was pretty scoured and good neve, where as other parties where seen going up to the message of pottage, Aladdins and Fluted buttresses. Some turned back, but some others plowed up - even though it was a Cat4 risk. So while they were making some (in my opinion) very careless decisions, our party had a good day on neve at the other side of the coire. No pits were nessessary to be dug where we were.

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