Avi size in relation to burial potential

[Ispoiler]

I was setting off small slides all day today, inbounds, close to the treeline and in the trees. Actually I am not sure if the kyber area is inbounds but its not all that steep. One may have been big enough to catch a person when the snow around a large rock let go.

Was I pushing it or just being concerned after the fact because I didn't stop riding the area.

Avi report had this to say "Snowpack: The January 19 layer of surface hoar is well buried below the surface and difficult to find in most areas. The cold temperatures during the past week have created a strong temperature gradient within the surface layers, and the faceting process has taken hold. On some alpine aspects and at treeline elevations the facets are loose on the surface, but in most areas a harder wind-affected slab prevails on the surface with underlying facets. Thursday's flurries initially created some pockets of loose snow which have since stiffened. As is usual, rocky areas have been particularly affected by the faceting process. All of this is now sitting under 38cm of new storm snow with more expected."

[RR]

I was setting off small slides all day today, inbounds, close to the treeline and in the trees. Actually I am not sure if the kyber area is inbounds but its not all that steep. One may have been big enough to catch a person when the snow around a large rock let go.

Was I pushing it or just being concerned after the fact because I didn't stop riding the area.

Avi report had this to say "Snowpack: The January 19 layer of surface hoar is well buried below the surface and difficult to find in most areas. The cold temperatures during the past week have created a strong temperature gradient within the surface layers, and the faceting process has taken hold. On some alpine aspects and at treeline elevations the facets are loose on the surface, but in most areas a harder wind-affected slab prevails on the surface with underlying facets. Thursday's flurries initially created some pockets of loose snow which have since stiffened. As is usual, rocky areas have been particularly affected by the faceting process. All of this is now sitting under 38cm of new storm snow with more expected."Translation: there's a big one coming....be smart!

[PWDR8S]

It only takes a couple inches of a slide to bury a person..... it all depends upon length of slope and how much area slides. Although the majority of deaths and burials are slabs and not sloughs, you could still lose it in a slough slide. Watch for terrain traps.... that trap could pin you at anytime under slough. You never know what may trip you up and then you might bonk your head, lose consciousness, yada yada yada.

You don't need a whole lot of steep to have a slide become dangerous. That would depend upon the makeup of the snow.

Carry a pocket of M80's a be ready to toss a few out when you need to set a few off or you just want to spook the neighbor out of his slumber. http://www.timefortuckerman.com/forums/images/smilies/tongue.gif
(I don't advocate or suggest anyone to actually do this... sliding with explosives is just plain dangerous!)

[BeerMouse]

avi report doesn't sound good. Obviously I'd look for other clues too but that report should have been a red flag. Interesting that they didn't give a rating...

[Affix Snow]

Things usually are more prone to slide around pockets of rocks right?

[pulverschwein]

I was setting off small slides all day today, inbounds, close to the treeline and in the trees.

Was I pushing it or just being concerned after the fact because I didn't stop riding the area.

All of this is now sitting under 38cm of new storm snow with more expected."

I'm guilty of this too. Around 10 or 12 years ago, before I had any formal avi training, xceiver, shovel or probe, a buddy and I were having a great day in Green Valley at Crystal, WA. We were setting off little sloughs on a small ridge, maybe 75 - 100 vert, 35 deg pitch and were in narrow chutes surrounded by trees. They'd break off about 6" deep, 6 or 8' wide and we'd ride them down like surfing a wave and had a blast. In hindsight, I'm still not sure how much risk we were taking. My friend got knocked over a couple times, but never buried at all.

I do think that 38 cm of new snow is beyond the depth I'd be comforatble playing with and is definitely in the dangerous category, but it depends on the width, runout and potential to trigger bigger releases.

[Justin]

Sounds to me you've got a snow pack that is quite inconsistant for one place to another and if there is one aspect of snow pack that concerns me the most it's inconsistency. the PNW is blessed with a more stable snowpack than other wester areas due mostly to terrain and snow saturation but with conditions like that i'd be concerned as well.

you said your self you were setting of little slides... warning sign number one. remember, a slide just a couple inches deep can become significantly more volatile given the right circumstances, i.e chutes, gulches etc.

[Jolly J]

Here is what the Canadian Avalanche Center says...

Size - Destruction Potential - Mass - Path Lenght - Impact Pressure
Class 1 - Relatively Harmless to People - 10 t - 10m - 1kPa
Class 2 - Could Bury, injury or kill - 10^2 t - 100m - 10kPa
Class 3 - Destroy Car, House, Damage Truck, Break trees - 10^3 t - 1000m - 100kPa
Class 4 - Destroy Railway Car, Large Truck, Several Buildings, 4 hect of forest - 10^4 t - 2000m - 500kPa
Class 5 - Destroy Villiage, 40 hect of Forest - 10^5 t - 3000m - 1000kPa

[Ispoiler]

The ratings at tree level and below were all High, and the area we were riding in is actually inbounds and we assumed safe. We were surfing the sloughs through the trees which prob wasn't the best idea.

[RR]

The ratings at tree level and below were all High, and the area we were riding in is actually inbounds and we assumed safe. We were surfing the sloughs through the trees which prob wasn't the best idea.Inbounds ain't always safe...there have been some slides under the Freezer at Jay...one of them buried a Touron at the base of Upper Exhibition. Scary, but non-fatal. They have since been pretty careful about opening it.

Plenty of runnouts are not all that obvious at a glance. It's a really good idea to look at the trees and vegetation for debris damage.

The best assumption to make is that it is not safe to make no assumptions about avalance paths.

[BeerMouse]

I don't remember his T4T handle, but Todd came across a slide that had just let go on a couple of kids on the upper snowfields at Sugarloaf.

RR is right, inbounds isn't always safe....

[PWDR8S]

Inbounds ain't always safe...there have been some slides under the Freezer at Jay...one of them buried a Touron at the base of Upper Exhibition. Scary, but non-fatal. They have since been pretty careful about opening it.

Plenty of runnouts are not all that obvious at a glance. It's a really good idea to look at the trees and vegetation for debris damage.

The best assumption to make is that it is not safe to make no assumptions about avalance paths.When I took Avi I with Chauvin Guides, the instructor said he got caught in a slide inbounds at Attitash a few years ago! It swept him off the trail and into the woods. He got buried. So inbounds isn't always 'safe' from slide activity.

[Justin]

I don't remember his T4T handle, but Todd came across a slide that had just let go on a couple of kids on the upper snowfields at Sugarloaf.

RR is right, inbounds isn't always safe....


el-bagr, he also alluded to a slide at sundayriver...

[pulverschwein]

a slide that had just let go on a couple of kids on the upper snowfields at Sugarloaf.

I've heard of that one, but not SR or Attitash, but I'm unaware of any inbounds east coast fatalities. Unlike out west:

May 20, 2005
Arapahoe Basin, Colo. (Ski Press)-A large in-bounds avalanche Friday morning killed one man at Arapahoe Basin on the ski area’s showcase Pallavicini trail.

Although details regarding what triggered the slide were still being sorted out at press-time, the ski area - which typically stays open for chairlift skiing into the summer - suspended the search at 12:30 p.m. as spiking temperatures increased the danger of further slide activity in the area.

I also have friends who routinely wear avi gear when skiing inbounds at Squaw and Mammoth. I know they've had some bad ones at those areas, including inbounds fatalities at Squaw a few years back.

[Justin]

I also have friends who routinely wear avi gear when skiing inbounds at Squaw and Mammoth. I


I've worn it inbounds many times, bridger (almost all the time), alta, snowbird, solitude Abasin, Crystal, the list goes on....