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Avalanche at Wisp

post #1 of 29
Thread Starter 
so this over at TGR. but this is why you dont make snow on top of natural snow.

here is the TR.
http://www.tetongravity.com/forums/s...d.php?t=141084




the web cam show it clearly on the left side.


just remember folks the laws of physics apply everywhere.
post #2 of 29
Oh...you make me SO jealous! That looks fabulous!
post #3 of 29
I remember a similar incident on the final pitch of the Grizzley Downhill, in preparation for the 2001 World Cup. The huge mound of frozen snow the guns had made cracked loose & partially buried the course designer Bernhard Russi. This opened up a whole new realm of concerns for the snow safety crew. All the course workers were encouraged to attend some avalanche safety training prior to working on the hill.
JF
post #4 of 29
Bush did the heavy man-made snow on top of natural cause the weak bond and pulled the whole snowpack off cause of the smooth ground underneath. Just asking cause I got no skills about the BC.
post #5 of 29
Quote:
Originally Posted by 4ster View Post
I remember a similar incident on the final pitch of the Grizzley Downhill, in preparation for the 2001 World Cup. The huge mound of frozen snow the guns had made cracked loose & partially buried the course designer Bernhard Russi. This opened up a whole new realm of concerns for the snow safety crew. All the course workers were encouraged to attend some avalanche safety training prior to working on the hill.
JF
I was there when that happened. Word spread VERY quickly and I got to see the fracture from very close up. That was impressive.

Snow is cool stuff.
post #6 of 29
Quote:
Originally Posted by Bob Peters View Post
Snow is cool stuff.
Yes, cool sometimes scary stuff.
JF
post #7 of 29
Thread Starter 
Quote:
Originally Posted by slider View Post
Bush did the heavy man-made snow on top of natural cause the weak bond and pulled the whole snowpack off cause of the smooth ground underneath. Just asking cause I got no skills about the BC.
I wasnt there, I if I was I could tell you for sure...

but my assumptions is what you spelled out.

Lots of heavy wet man made that was sprayed on top of 6 inches of natural snow that was up there.
post #8 of 29
A similar event happened at a place in SE Indiana a few years back.
Except that incident took out one of the towers of the adjacent triple chair. It happened after hours so no one was on the lift at the time
post #9 of 29
Just speculating, but for an early snow the ground may have still been warm underneath. Wet grass under snow? Sounds like trouble.
post #10 of 29
They were spraying man-made on top of the powder at Snowshoe, WV as well.

Someone should forward the Wisp pic to them as well.

If I could get it through to someone at Snowshoe I would. All they do is play pass the phone call.
post #11 of 29
Quote:
Originally Posted by NeedToSki View Post
A similar event happened at a place in SW Indiana a few years back.
Except that incident took out one of the towers of the adjacent triple chair. It happened after hours so no one was on the lift at the time
The place is Perfect North Slopes, about a half an hour from Cincinnati. It has happened there probably a half dozen times in the last 10 years. I can't think of any time though when it was caused by man made snow being blown on top of fresh snow. Its usually in the later half of the season when there are a bunch of freeze-thaw cycles happening.
post #12 of 29
Thread Starter 
Quote:
Originally Posted by Johnnys Zoo View Post
They were spraying man-made on top of the powder at Snowshoe, WV as well.

Someone should forward the Wisp pic to them as well.

If I could get it through to someone at Snowshoe I would. All they do is play pass the phone call.
I could just see lower shays going to the ground and taking out the quad
post #13 of 29
<some poacher told me it was knee high in the oob>
post #14 of 29
Quote:
Originally Posted by Johnnys Zoo View Post
They were spraying man-made on top of the powder at Snowshoe, WV as well.
They might be alright if they run a groomer on it.


IIRC* that bit of Wisp's front side has a fair bit of convexity to it, both from the top, and towards the woods on the right.
post #15 of 29
Very interesting. Thanks for the link.

It appears that all the elements were present. I've only read about avalanche science, haven't studied it enough to ski unpatrolled terrain yet (even in home state of Maryland!), but unconsolidated snow on a smooth surface (wet grass) under a heavy load of more snow, the convex terrain right there, the fact that this is one of the few inbounds pitches in the region that is actually steep enough to be in the range of gradients most likely to slide. The picture in the TGR thread taken the next day under clearer skies shows the whales of manmade. Undoubtedly one whale sat on that trail just downhill from where it steepens.

That's cool that ski patrol didn't hassle the intrepid trespassers. I would have given a lecture about route selection, haha.

Go Terps!
post #16 of 29
Quote:
Originally Posted by slider View Post
Bush did the heavy man-made snow on top of natural cause the weak bond and pulled the whole snowpack off cause of the smooth ground underneath. Just asking cause I got no skills about the BC.

seems to me that the man made bonded quite well with the natural snow underneath. The weak layer was where it slid which was the ground. My guess is the ground may have been rained on, then frozen, then fresh/natural snow, then man made snow. the man made bonded to the fresh/natural and the icy layer on the ground could not support the weight. What was the trigger is what I want to know.
post #17 of 29
Quote:
Originally Posted by Johnnys Zoo View Post
They were spraying man-made on top of the powder at Snowshoe, WV as well.

You should not be concerned about making snow on top of the natural/snow. The two different snows did bond/consolidate clearly. If there was more natural snow instead of man made you prob would have the same results.

The weak layer was the ground. not the top of the natural snow.
post #18 of 29
I had this happen at times way back when I was a snowmaker. Making snow on top of natural snow is not in itself a problem. Manmade snow can be made with varying amounts of water in it. Wet manmade snow can contribute water to the layers below and consolidate it nicely. Rather the problem there is a lack of slope anchors (i.e. rocks, bushes), coupled with a heavy snowpack. Manmade snow is generally denser than natural snow.

We actually buried a sled on a beginner trail one night from overspray that built up on a side slope.
post #19 of 29
Thanks guys. Was it just too much weight that finally triggered the slide?
post #20 of 29
Quote:
Originally Posted by slider View Post
Thanks guys. Was it just too much weight that finally triggered the slide?
That's what it looks like to me.

Kinda good thing in a way, that it slid now before it got a solid top crust.
post #21 of 29
Crazy start to the season out east.

We've had that before at Holiday valley in wny too. I think its been the connection to the grass that let go both times and the slope is somewhere around 37 degrees.

I didn't see this one in person






What do you guys mean when you say the hill is convex?
post #22 of 29
Quote:
Originally Posted by Garick View Post
What do you guys mean when you say the hill is convex?
There's a bulge right there so it's steeper lower down than up top, and steeper to the right than in the center.
post #23 of 29
Water, H2O, is the most common substance that its gas (steam), liquid (water), and solid (ice) phases are widely known.
post #24 of 29
Quote:
Originally Posted by comprex View Post
They might be alright if they run a groomer on it.


IIRC* that bit of Wisp's front side has a fair bit of convexity to it, both from the top, and towards the woods on the right.
I was actually wondering about whether grooming would effect this type of thing. fwiw, in the 10 or so times I've been to Wisp, I've never seen that run groomed. They just leave those mounds of man-made snow on skiers' left. It's one of their steeper runs, but there's usually noone on it (I'm guessing because of the mounds).
post #25 of 29
Quote:
Originally Posted by Nick29 View Post
I was actually wondering about whether grooming would effect this type of thing.
fwiw, I was referring to Snowshoe up^ there

Quote:
They just leave those mounds of man-made snow on skiers' left.
Ah, the Wisp glacier, yes.

Quote:
It's one of their steeper runs, but there's usually noone on it (I'm guessing because of the mounds).
It's also short. Last time I was there we were doing 6-turn laps on it.
post #26 of 29
Quote:
Originally Posted by comprex View Post
fwiw, I was referring to Snowshoe up^ there
Yeah, I got that. I was talking in general terms.

Quote:
It's also short. Last time I was there we were doing 6-turn laps on it.
True, but it's probably the steepest trail they have. Bobcat Bowl isn't too bad (a little less steep/a little longer), but it's only been open once when I've been there and riding two lifts to do laps on a trail that short sucks.

Beggars can't be choosers though. I'm just happy that I'll get to ski in November for the first time this year
post #27 of 29
Didn't these guys watch Grumpy old men?
How was it that Walter Matthau got the avalanche to come off the roof onto Jack Lemon?
post #28 of 29
Quote:
Originally Posted by Trekchick View Post
Didn't these guys watch Grumpy old men?
How was it that Walter Matthau got the avalanche to come off the roof onto Jack Lemon?
I think Wisp's webcam showing 'Tilt Limit' is teh funneh. Something slid?
525x525px-LL-vbattach4247.jpg
post #29 of 29

wisp avalanche

That's manmade on grass. not new snow. The new snow didn't start until later. Close to thirty inches in a week. Then rain for a day, now 4-8 by tomorrow at noon. alta is for skiers. rc is god.
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