basically it is the opposite of the crown. so the very bottom of where the slab broke loose. there is a good picture of one in the red baldy avy tr in the "slide zone". or check the "anatomy of an avalanche" thread.Quote:
Originally Posted by greg
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basically it is the opposite of the crown. so the very bottom of where the slab broke loose. there is a good picture of one in the red baldy avy tr in the "slide zone". or check the "anatomy of an avalanche" thread.Quote:
Originally Posted by greg
nice sunny high pressure day. we summited Mt. Raymond and chose to do some stability testing on a chute just south of the summit. we dropped a 1 ton cornice that produced aprroximatly a 1' crown x 20' x 15'. it broke on faceted snow with a crust as the bedsurface. below the crust was more faceting. the slab had obvious signs of windloading on it. it may be hard to see but it is pillowy there.
http://www.biglines.com/photos/blpic34934.jpg
the crown:
http://www.biglines.com/photos/blpic34940.jpg
the cornice was cut and uncovered the older cornice still visible in this pic. the one dropped was near 1 ton but did not impact the slope that hard:
http://www.biglines.com/photos/blpic34933.jpg
you can see the hangfire and we didn't mess too much with it but enough to find out from a safe area what the story was.
edit to add that when tested the slab produced a Q1 shear that released when isolating the block. the bedsurface was only 1-2mm thick and had plenty of faceting (fist) above and below. the aspect of the chute fall line was due east and the shady slope that produced the slide was more ENE/NE.
the dynamic properties of snow never cease to amaze me. surfers would kill for a wave like this cornice:
http://www.biglines.com/photos/blpic35230.jpg
trackhead, here you go:
west aspect, ~10,000' and 2 pits. compression tests weren't real effective since the slope wasn't that steep.
1st pit had about a Q1-1.5 in the top 1' breaking on facets. down about another foot there was a 3" pensil hard slab surrounded by facets (fist hard) and a melt/freeze (pensil-knife hard) about a foot thick. really interesting but not of real concern for our trip.
http://www.biglines.com/photos/blpic35234.jpg
the slab with the saw in it is a good bedsurface and the weak layer above (facets) is of concern with any sort of new heavy snow or loading. we'll have to see what rb has to say about the new snow and possible winds coming. just remember that the provo mountains have a little more active weak layers currently than we do around here.
http://www.biglines.com/photos/blpic35233.jpg
huge facets. this depth hoar was found about 3' down in the 2nd pit. it continued throughout my pit.
http://www.biglines.com/photos/blpic35232.jpg
i dropped a cornice on the east aspect with near nil vis and a few minutes after i stopped trying to see results and skied away i got this nice vis:
http://www.biglines.com/photos/blpic35231.jpg
Thanks APD.
conditions are looking good right now in most places. as i pointed out to a friend who soloed east twin yesterday, glide avys are ready to go again. he did it friday and my response was it should be good but i would not do it saturday or later. that was just a guess but they are unpredictable and out of our control. all we can do is avoid them.
well, here's what happened saturday in broads fork:
http://www.avalanche.org/~uac/Adviso...ads%20glde.JPG next, there are still a few small windslabs were there is loose snow to blow around. either avoid them or make sure they won't pull you off a cliff, into trees or thru the rocks. lastly, this wet slide prime time so work your aspects. get out early and ski the east faces first, south faces next and wet faces last if you're out farming corn. wetslides are the easiest to avoid. if you are sinking in past your ankles then it is time to find another aspect or call it a day.
here's an example of staying out too late on the wrong aspect:
http://www.avalanche.org/~uac/Adviso...et%20slide.JPG on a day as hot and sunny as saturday was, you should not be on a SE aspect at 2:30pm unless you are confident that it was not adequatly heated in the morning.
well the deep freeze is here. things seem solid right now though sastrugi and wind effected terrain is still evident from the weekend 40-80mph winds:
http://www.biglines.com/photos/blpic36313.jpg
broke trail thru about 2' of fresh and transport. spent the afternoon (1:30-4pm) just looking around cardiff pass. coming up pole line i found the east aspects loaded and very sensitive from the upcanyon winds. they were cracking about a foot deep or better. at the pass you could see the north aspects were loaded but the winds had shifted and things began to load on the south aspect. the visibility, which was not good to begin with, became worse. i headed over to the superior ridge from the weather station and remotely triggered a small 4-6" soft slab from the ridge. http://www.biglines.com/photos/blpic36696.jpg
i went a little further and dropped a little fresh 25lb cornice that propogated over to a nearby obviously loaded chute. it did not appear to have broken into any old snow at the deepest part (~1') of the crown. in the pic you can see it wrapped around the next ridge into some cliffs. it may have pulled out more once it reached the chutes apron but vis was horrible and the trasport blowing onto the south aspects was picking up. http://www.biglines.com/photos/blpic36697.jpg
http://www.biglines.com/photos/blpic36698.jpg
anything without a north facing cornice was starting to develop a south facing one. winds didn't seem to get above ~30mph.
to be honest, it was easier going up than going down. steep slopes were needed for downhill travel but i wasn't about to head down cardiff ridge with pillows above me.
any obs from today? Thinking about Cardiff or Patsy Marley tomorrow.
my only observation was that some people don't tip very well.
i worked all day but i wouldn't have been too excited to get out and ski anything steep. winds changed a bit and lots of new snow is on the ground. i'll take a look at the snotells tonight and decide if it's going to be an inbounds day or not for tuesday.
I was out in Rocky point/Patsy Marley area today. We heard and felt settling in a rocky area on a NE aspect. I also made a block/small slab move on an East aspect, it sheared clean about a foot deep on a small rollover, but it wasn't steep enough for it to travel very far. Later, on a Southerly aspect, a small, 6 - 8" deep wind compressed slab pulled out, but again the terrain wasn't steep enough for it to move very far. There was also heavy wind loading on the N through E aspects off the upper ridgeline today.
yeah, i spoke with an exum guide about some of this today. he said that he felt it was sketch now and would be hitting the resorts after this next storm rolls thru. 3' on top of a layer of facets that is already active is going to be nuts. 5 taps from the wrist is all that it is taking on the NNW aspects in silver. doesn't bode well for this new snow staying put.
i am not all that happy about skiing steep slopes right now before the next storm. it can be done in certain places but the resorts are so damn good right now that it isn't even a choice for me.
These photos are from 8100' on a north facing ridgeline. I was just walking the ridge on a little exploration this morning and this guy pulled out, about 4" from my downhill ski. 34-38 degrees, 20" crown and 30' wide. It pulled down to the facets from the last dry spell and there was a little dirt layer indicating the wind from the start of the first storm last week. I'd keep clear of northerly aspects and use caution on ridgelines - like the avie report says today.
looking east along the ridge I was traveling on
http://www.feedthehabit.com/pics/ski...leys_slab3.jpg
looking west - notice parley's canyon down there
http://www.feedthehabit.com/pics/ski...leys_slab4.jpg
It didn't run far - wouldn't bury you but it'd knock you down and perhaps into a tree or two
http://www.feedthehabit.com/pics/ski...ab_debris1.jpg
debris from another angle
http://www.feedthehabit.com/pics/ski...ab_debris2.jpg
slope angle - 34 degrees
http://www.feedthehabit.com/pics/ski...slopemeter.jpg
Be safe out there.
http://www.biglines.com/photos/blpic37151.jpg
i dug a 9.5' deep pit on a north facing 35* slope at 9,500'. shovel shears produced q2's on a couple slight density inversions and a gaupel layer. each were about 1' apart. R4's and 5's on the same weakly bonded layers.
facets 5.5' down:
http://www.biglines.com/photos/blpic37149.jpg
http://www.biglines.com/photos/blpic37150.jpg
5 taps from the shoulder got the facets to fail. i believe this is the same layer that was active just before our large storm cycle. R-7 -- no failure. i had some trouble isolating the back of the block to that depth so that would have been an issue here. i would guess that it would fail as an R6 had i been able to completely isolate it.
the 3" facet layer shown was what i like to call 2 finger hard or just a little harder than both 4F & fist hard. the 5" below it was also faceted but it was 1F hard. and did not fail in the compression test.
a natural that ran sometime during or toward the end of the last storm. i think this was the maybird/hogum ridge but i can't remember. i took a pic and couldn't remember which one it was for sure. this is a north to northeast aspect:
http://www.biglines.com/photos/blpic37152.jpg
edit: it was the maybird/hogum ridge
the warming has played a factor in these two slides:
http://www.biglines.com/photos/blpic37549.jpg
http://www.biglines.com/photos/blpic37550.jpg
they appear to be 1-3' deep on average and were natural slides of a SE aspect helped on their way by the sunny sky. the SE slopes were crossloaded by upcanyon winds during the storm.
there are unstable slopes out there. be careful over the weekend. we are sure to see more slides tomorrow but i hope no one is there for them to pose a threat to.
i guess you could call these trees flagged. we were on a ridge when this pic was taken. a massive slide took out areas that would otherwise never see mcuh action.
http://www.biglines.com/photos/blpic38219.jpg
this tree is flagged to 45' high. the highest branch i observed broken was on a tree further down hill. the branch was 65' high.
http://www.biglines.com/photos/blpic38218.jpg
just a few snowpack obs:
on E,S and W slopes there is atleast a one inch crust formed that is supportable at upper elevations. mid elevations are hit or miss and lower elevation is just heavy, melted and rained on snow. the E aspects at mid elev had a 2" thick crust that was destroyed by faceting with a coupel feet of wet snow beneith. S aspects had a supportable crust with a couple feet of wet below. upper elev N aspects had 4" fresh with a paper thin crust that wasn't noticable while skiing, just in the pit. no wet snow was observed at high elevation on the north slopes. earlier in the day winds blew in the 20-30mph range and out of the NE loading SW slopes in lcc.
That is some impressive flagging!!!!!!!
http://biglines.com/photos/blpic39286.jpg
^ A Wellsville cornice looms above Cache Valley and Hyrum Reservoir, The Bear River Range is in the distance.
http://biglines.com/photos/blpic39287.jpg
^ Early Morning Corn
Quote:
Originally Posted by Elitist
Wow thats impressive, BUT I CAN"T SEE SHIT!!!
plenty of good snow to be had on the shady aspects. the old snow is still quite warm on the sunny aspects covered with ~12" of new, which lead to some push-alanches. on the upper elev ridges the pillows were up to 4' deep in some spots and were propogating fractures with low energy. @30* they would fracture but it took 35*+ to get them to move. most of what i found was confined to between 1 and 2 feet but easy to spot. they were layered but all ran on the old snow interface at what looked like a density inversion. lots of old slab and slough activity was noticed on all aspects. N had some slabs, E had minor sloughing in most spots and some far running skier triggered wet sloughs.
http://www.biglines.com/photos/blpic39067.jpg
http://www.biglines.com/photos/blpic39068.jpg
in the top left center of this pic you can spot the debris from the first pic:
http://www.biglines.com/photos/blpic39069.jpg
there was about 2' of light on fluffy on the shady slopes. it sloughed easily but ran slowly in most places. visibility went away right about 3:15 and it began to snow. the winds became gusty in the moderate range out of the SSW. it looked like another 1" of snow may have been added at the end of the day before it stopped snowing around 5:15. the snow was intermittent so it may have started again.
Today at Brighton Lots of instabilities. Poor bonding of new snow. Then sun came out and heated things up. Wanted to bag Millicent Peak,but it wasn't going to happen under these conditions. A small release here.
heavy rain was observed up to about 9,500 yesterday. maybe it can help lock up some of the snowpack around here.Quote:
Originally Posted by AltaPowderDaze
a runneled slope from the slide activity on 4-22:
http://www.biglines.com/photos/blpic39203.jpg
East and Southeast slopes seem to be active lately. i haven't had a chance to look at any of the crown profiles yet but i assume that in the first pic the rain/sun or a combination did a number on a deep suncrust. in the second pic it seems that the crust ~8-10" down hasn't had a chance to furrow yet and is impeding the melt water from finding its way to the earth. coming out of a lower sunny drainage a few days back we noticed a 1' crown x 100' wide east slope that slid wet either before we got there or the day before. so in short, the east aspects have been busy.
http://www.biglines.com/photos/blpic39478.jpg
http://www.biglines.com/photos/blpic39479.jpg
wet sloughs were the concern for the day. 8-12" fresh high density snow sitting on a partially suportable rain crust in most areas. under the unfrozen crust was 1-2 more feet of soft unfrozen mank. a half hour of sun around 11am did the new snow in and allowed it to move on slopes over 35*. all it took was for a skier to remove a little tensile strength from steep slope and it was point release city. it did take a while to run its track but most were not dangerous to skiers except for exposure concerns. this one was big enough to possibly bury a skier:
http://www.biglines.com/photos/blpic40193.jpg
the rest entrained quite a bit of snow and would be problematic to be tangled in but would pose little danger to those that either stayed in front of or above the moving snow. slope cuts told the tale but left an almost supportable bedsurface to ski down. clearing your skis from the snow was the best way to manage.
http://www.biglines.com/photos/blpic40191.jpg
rollovers were sure places to do damage if you wanted to get a pushalanche going.
http://www.biglines.com/photos/blpic40192.jpg
slope angles and time of day were the most effective way to minimise your impact on the new snow. a drop in temps would be welcomed before our next round of storms.
Yesterday it seemed that the heavy density snow at lower elevation was bonding better than above 10k. The steeper slopes in Wolverine were fracturing w/ ski cuts quite easily and running full track. I was a little slow on the shutter of this pic, but you can see the wide fracture and the sluff pouring over the 1st steep rollover from the top of Mt. Wolverine. Will be interesting to see how the addition of new snow late yesterday and last night affects conditions today.
Damn I miss the UAC and NOA Cottonwoods forcast. Thanks for your avvy posts APD
.http://i5.photobucket.com/albums/y19...bum/ski078.jpg
point releases like yesterday's were less common but were still around. by the time we got there most had run but it wasn't too much effort to move a good sized slough if the terrain was steep enough. hopefully tonights colder temps can curtail some of the action and lend us a few more faceshots in the morning.
just remember that we have over 2" of water weight in 48hrs on not so frozen old snow.