Home > Trip Reports > October 27, 2010, Paradise ( Observations )

October 27, 2010, Paradise ( Observations )

10/27/10
WA Cascades West Slopes South (Mt Rainier)
15888
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Posted by CookieMonster on 10/27/10 10:07pm
At Paradise on Wednesday afternoon.

Weather: Mostly sunny and cold with wind. Patchy orographic clouds drifting over from the Tatoosh.
Accumulation: 3-4 feet in most places and already well-consolidated.
Stratigraphy: a mix of decomposing and fragmented particles with ~1cm thick 'section' of plates / mixed forms ~30cm from ground ( in protected areas ). Obvious rounding in progress from moderate temps. 4f near top to 1f at base.

Took a look around Mazama Ridge, which had been heavily cross-loaded. Direct sun caused heavy sluffing on steep slopes and rising temps turned the snowpack into grabby-rubbery-chalky-cement. Also toured up around Altavista, which was nice and warm in protected areas. Obvious wind loading in progress above treeline on Rainier and in the Tatoosh.

Overall, not much fun for skiing, but it was great to get out in late October.

This will be a great base if it sticks around.
Good info, Cookie.
Thanks.

Thanks for the briefing, CM.

Sure thing Sharks!

Hopefully the snow quality improves with additional consolidation or cold storms.

Yes thanks for the input Cookie.
Let's hope that there is no hoar frost layer that gets involved in this lower layer. I assume that the pack is low enough that there are enough shrubs and brush that it would eliminate most of the concern in the case of hoar frost.
What tends to be the trend in a early snowpack with a warmer (early season) ground and cold top surface? More rounding of the snow at the bottom near the ground?

Hoar frost forms during clear cold nights, on surfaces that face the sky. There are two essential requirements for surface hoar formation: moisture supply from humid air and intense cooling of the snow surface from longwave radiation loss. Vegetation such as trees inhibits cooling by reflecting longwave radiation back at the snow.

Terrain features such as concave areas also reflect longwave radiation back into the snow cover, which will inhibit surface hoar formation in some places. There are some significant scale issues with respect to the size and geometry of the terrain features to which this applies.

The spatial distribution of hoar frost has some "patterns". It's usually most dangerous in clearings; it's easily destroyed in the alpine; it often is most problematic at a specific elevation band.

*

The current snowpack at Paradise ( from a FEW observations ) was very consistent throughout. The layer of plates that I found may or may not be found everywhere, but I bet it's already rounded itself out of existence. For current stability concerns, the increase in hand hardness with depth indicates that the pack itself is strong. This doesn't mean that avalanches aren't possible, and I would expect that it is possible for full depth avalanches in a variety of locations. Given the highly uniform stratigraphy I observed, I wouldn't expect avalanches to form within the snowpack itself. With warming, loose snow avalanches could form at the surface.

*

There isn't an easy answer to your question about trends.

The simple answer: the predominance of rounding or faceting depends entirely on the magnitude of the temperature gradient across space and time.

I would classify the current snowpack as thin in many places, especially after consolidation. Thin snowpacks are very prone to faceting throughout, including depth hoar formation at the bottom of the snowpack. The continuous application of cold temperatures to thin early season snow has created incredibly dangerous conditions in British Columbia ( winter 2003 ), but I don't think this is generally the case in Washington.

The following is *rank speculation* on my part:

There exists significant variance with respect to the spatial distribution of snow at Paradise. If the weather remains generally cold and dry over the next couple of weeks, then I would expect depth hoar to develop at locations where the height of snow is less than 1 metre.

On the other hand, if we see generally warmer temps, then the snowpack may continue to round, or it could become isothermal and rot. There could be significant variations with elevation, where perhaps rounding is predominant in the lower elevation snow cover, and faceting is predominant in thinner areas at higher elevations.

*

The weather manufactures the snowpack in poorly controlled, highly chaotic conditions. We'll have to see what it has in store! It's a high uncertainty situation until there is more weather data.

Fair amount of consolidation today.  On the steps above the Panorama Point overlook today there were 4+ inches of new snow over a wet, icy crust; the new snow slid while trying to skin up the lower step; FWIW.  Lots of exposed rock around.  Wet cement just above Paradise Parking Lot.  However, nice nice powder on Pan Face for the ski down :-).  But it sure looks like the present snow will be substantially consolidated, if not gone, by Wednesday.

If you spend a little more time on the lifts the backcountry skiing will become fun on the way down too!

Way to get after it thought... Any pics or vid?

BEST,

TNT

author=The Snow Troopers link=topic=17747.msg75051#msg75051 date=1288459055]
If you spend a little more time on the lifts the backcountry skiing will become fun on the way down too!

Way to get after it thought... Any pics or vid?

BEST,

TNT


No pictures, no video.

I'm not sure what you mean about the relationship between spending more time on the lifts and having more fun on the way down. Can you clarify?

author=CookieMonster link=topic=17747.msg75059#msg75059 date=1288463844]
No pictures, no video.

I'm not sure what you mean about the relationship between spending more time on the lifts and having more fun on the way down. Can you clarify?


I think he was trying to say that your skiing would improve if you rode the lifts more.
He's obviously ticked off about your comments regrading spammy posts on TGR but rather than say it direct, is doing so in a passive/aggressive way.

Could be wrong but thats' my interpretation.

Oh I'm sure that he would address me directly if he had something to say.

Hello my name is Tim & I too AM an Alpentalic who loves to ski lifts, bc, or simply do ski skin walk up to check out my favorite stompin grounds Silver Peak as I did last night (ready for some turns next big dump). I live on Snoqualmie Pass, which many of you know, and now drive an eight hundred dollar awd mini cause that's what could afford. The bright side of the mini van is not only how hip they have become again but the fact it can haul 6 of my best ski friends which you could be one of someday(maybe, if your strong... cause I feel 6 strong friends can push it just fine). I guess to put it simply when we are on the snow we all have  the same doesn't matter if you work at Micro Soft (I can say that plug because I have no connection) or load lifts, just go ski and if you don't like me so be it but please don't keep throwing rocks under my wheels, I can't afford to replace them and my friends want to ski not push the rig. 

Anyway long of the short I would tell you what brand skis I think might make your bc adventures when our friend Crusty the Clown is back in town but that would disrespect my friend Marcus, so Drop me note sometime to ski or cht, but will tell you now wide(per weight ratio... apx 250lbs on my 136mm under foot was my set up for a 49" on nothin day), rockered, cambered, and directional tails. I brought my 8.3 lbs. x 96mm under foot but they stayed in the car once my eyes saw the Glory!!!

Live to Ski Another Day Snow Troopers!
TNT

ps If I didn't catch a cold from one of my 50 snow lovin friends that passed me on the trail Wed I would be out w/ my boy trooper living large.

???

What is this, AMWAY?

Cookie, back to the subject at hand somewhere between your observations on the 27th and today the 31th there was a down to the ground slide in Edith basin SE aspect on the north end of ALta Vista ridge.just south of the saddle with pan point ridge. Most likely triggered by warming snow on trees or cliff face . Side walls better than 2' . Took the whole thing down to the flats.500'long perhaps 80' wide.
We steered clear of similar.
sorry no photos I left my chip at home.

Robie, Thanks for the observation. Sounds like a classic thaw-induced slab. Do you have any idea about the depth of the deposit?

I'd be guessing but maybe 5 or 6 ' .Ron J has a pic and will post it.
There was some rain up there as well so could have been lubed up. It didn't run up hill any but stopped as slope flattened out.

Here's some shots of the slide Robie mentioned:







More shots from a slightly different angle HERE (along with a few shots of the usual suspects).

As an interesting aside, we dropped a cornice at that very same location a couple of years ago and JW shot video of the process:
http://picasaweb.google.com/ron.jarvis/Paradise09#5534419346587040482



Hell of a release.  Took several photos of it from Mazama Ridge today.

Ron, Thanks for the amazing photos. Looks like a Size 2 to me.

Thanks for the conditions info and great pics.

author=Joedabaker link=topic=17747.msg74998#msg74998 date=1288370614]

What tends to be the trend in a early snowpack with a warmer (early season) ground and cold top surface? More rounding of the snow at the bottom near the ground?



Huh. Here's my thinking: Since it's the relative warmth of the ground and the coldness of the snow that creates the temperature gradient promoting faceting at the bottom of the pack, if the ground is warmer than it would be mid-winter then I guess the somewhat warmer ground could further encourage faceting. If the ground were warm enough I reckon it should promote melt or tend to round the grains.

Maybe warmer ground temp was a factor in producing a bed for the slide Ron posted pics of? That it went to dirt sure looks like there was faceting at the bottom of the pack. Or is the thought that rain & some melt off the rocks got to the ground, later froze, and the pack didn't bond to it?

Here's my thinking.  It rained a lot!

author=natefred link=topic=17747.msg75140#msg75140 date=1288635342]
Thanks for the conditions info and great pics.

Huh. Here's my thinking: Since it's the relative warmth of the ground and the coldness of the snow that creates the temperature gradient promoting faceting at the bottom of the pack, if the ground is warmer than it would be mid-winter then I guess the somewhat warmer ground could further encourage faceting. If the ground were warm enough I reckon it should promote melt or tend to round the grains.


The temperature gradient required to induce faceting is created by the difference in temperature between the relatively warm ground and the cold atmosphere. The difference in temperature between the ground and the overlying snow cover does not cause faceting. In some cases, temperature differences between old snow and new snow can build instability. Bruce Jameson refers to this a dry-on-wet faceting.

http://avalancheinfo.net/Newsletters%20and%20Articles/Articles/JamiesonPBCrusts1.pdf

author=natefred link=topic=17747.msg75140#msg75140 date=1288635342]
Maybe warmer ground temp was a factor in producing a bed for the slide Ron posted pics of? That it went to dirt sure looks like there was faceting at the bottom of the pack. Or is the thought that rain & some melt off the rocks got to the ground, later froze, and the pack didn't bond to it?


I'll put a 1:10000 chance that there were any facets at the bottom of the snowpack. Your first inclination is most likely correct: this slide was almost certainly caused by a combination of rain, warm temps, and the slip of the snowpack that occurred as a result.

Wow, I skied that shot on Wednesday, and stayed as far skiers left as I could without getting into the mini-gully. Thanks for the pics.  A good reminder that even small terrain can have bad consequences with the wrong conditions.

author=andyrew link=topic=17747.msg75145#msg75145 date=1288637924">
Wow, I skied that shot on Wednesday, and stayed as far skiers left as I could without getting into the mini-gully. Thanks for the pics. A good reminder that even small terrain can have bad consequences with the wrong conditions.


Good point.
That gully you refer to skier's right of the subject slide I refer to as "Reiser's Couloir" in memory of Kirk Reiser that was buried there in a self triggered slide and laid at the bottom of that waterfall for a few days in December of 2007 (a very bad year with regard to early season avy fatalities).


awesome photos, that's amazing, thanks for sharing

Cookie,
Totally agree that air temp is big factor in overall gradient in the pack. But isn't the key simply the existence of a temperature gradient (whatever's causing it), especially a high local gradient?

Earth at some temperature greater than freezing, snow on top of it at some lower temperature, small gaps due to groundcover where crystals have room to grow. Would it have been possible for faceting to occur despite the warm air temps? Heck if I know. So far I'm hearing no, not possible. If we can get frost all over the yard on a 30° night, could a similar phenomenon occur at the bottom of a 30° pile of snow on top of grass and shrubs? the bed surface at the ground makes me wonder aloud.

I hope you don't interpret this as an argument and thanks for discussing, I only know enough to know I don't know what snow does in its spare time. I learn something whenever I log on here & ask questions.

Did anyone get a look at a similar pit at the same time on the same day on the same aspect at the same elevation? The crown?

There are no substitutes for accurate, precise, and representative observations.

Also, that slope is almost as anchor-free as they get. There's a whole subfield of study on wet glide climax avalanches on smoothly vegetated slopes in Japan.

Oldtimers used to call that shallow saddle below Pan Point & the nearby overlook into Edith Basin  'Angel's Landing'.  My name for the slope where the slide occured is 'Angel Face'.

I wonder about the rain explanation.  Was this the only slide that day?  Wouldn't rain have likely produced other slides nearby? 

I've noticed over several decades that 'Angel Face' consistently produces large glide cracks each Spring exactly in the area where this slide occurred, when other nearby slopes with similar steepness & aspect do not.  I've always wondered about the cause of this; perhaps there is slightly higher volcanic heat flow in this localized area?

when I google "wet glide climax" (okay you have to include "avalanche" to get meaningful results..), 1st hit has info about wet slabs being initiated by water percolating to and lubricating an existing weak layer. sure seems like grass or similar vegation makes a good 'weak layer', at least it can be damn slippery when wet. if faceting were an issue probably some other slightly better anchored slopes would have slid?

I'm having a "doh" moment, but you can count on me to keep overthinking and asking potentially stupid questions!

Check out the 8th page starting in the 2nd column: Going to Sun Road paper

I hate to slice and dice so much, but I'll try to answer your questions.

author=natefred] Earth at some temperature greater than freezing, snow on top of it at some lower temperature, small gaps due to groundcover where crystals have room to grow. Would it have been possible for faceting to occur despite the warm air temps?


I have never heard of this explanation in any literature that I have ever read. If you're curious, you can review work by Sam Colbeck ... he elevated this type of research to an art form. Also, the link I provided in a previous post discusses dry-on-wet-faceting, which is similar to what you describe.

To answer your question, I don't think the scenario you describe could lead to faceting. If for some reason the rocks had a significant amount of latent heat, I think it would lead to snow melt. Remember temperatures "greater than freezing" cause snow to melt.

author=natefred]If we can get frost all over the yard on a 30° night, could a similar phenomenon occur at the bottom of a 30° pile of snow on top of grass and shrubs? the bed surface at the ground makes me wonder aloud.


No, you can't get this type of frost formation at the bottom of the snowpack. You can get cavity hoar, but I don't think there is a relationship between cavity hoar and avalanche formation.

author=natefred]sure seems like grass or similar vegation makes a good 'weak layer', at least it can be damn slippery when wet.


You are correct. This is referred to as a weak interface.

In the first post of this thread, I discussed the possibility of full depth avalanches based on a few limited observations of the stratigraphy. I don't know enough about the ground cover in the area, nor the avalanche history, but Vogtski's discussion of annual glide cracks in the area certainly firms up some of the conclusions in this thread.

When I google "wet glide climax", I get a bunch of links that are NSFW!

And ... there are no stupid questions. The Avalanche Handbook has an excellent chapter on snow metamorphism.

author=CookieMonster link=topic=17747.msg75164#msg75164 date=1288648085]

When I google "wet glide climax", I get a bunch of links that are NSFW!


oops, that's what I meant to imply, you need to add 'avalanche' to stay out of trouble!

Not related to this situation, but: I thought hoar at the bottom of the pack is the weak layer which typically makes climax slides possible. Forms early season with shallow pack and cold temps, and may persist until additional load results in a slide. Yeah temp's warmer than freezing cause melt, I guess my point was "earth warm, snow cold", they are next to each other and therefore temperature gradient will be quite high. Sure looks like lack of anchoring and rain are the keys here, thanks for taking time to entertain my curiosity. I'm interested and could clearly benefit from some reading.

author=natefred link=topic=17747.msg75168#msg75168 date=1288652905] Forms early season with shallow pack and cold temps, and may persist until additional load results in a slide.

Yeah temp's warmer than freezing cause melt, I guess my point was "earth warm, snow cold", they are next to each other and therefore temperature gradient will be quite high.


Think the  first sentence more applicable to Continental snowpacks than Maritime but it does occur here. This is what all the Coloradians fear and a perennial gripe of the early season CO weather.

Second sentence. Temp gradient high but above freezing is above freezing.

That area very slide prone from my experience: Grassy and at right angle facing mainly south.( still heat in the sun at this time of year)
There was a slab release on that slope ( to the left of the one pictured here) that was documented on TAY last winter, different circumstances but still that slope area = very slide prone.
Interesting discussion.. I learnt some stuff.

author=natefred]Not related to this situation, but: I thought hoar at the bottom of the pack is the weak layer which typically makes climax slides possible. Forms early season with shallow pack and cold temps, and may persist until additional load results in a slide. Yeah temp's warmer than freezing cause melt, I guess my point was "earth warm, snow cold", they are next to each other and therefore temperature gradient will be quite high. Sure looks like lack of anchoring and rain are the keys here, thanks for taking time to entertain my curiosity. I'm interested and could clearly benefit from some reading.


Depth hoar forms anywhere you have a predominantly thin snow pack and cold atmospheric temperatures. As Scotsman notes, Colorado is well-known for thin snow packs, cold temps, and depth hoar. The danger of depth hoar as a weakness is often overstated. According to The Avalanche Handbook, if depth hoar were as dangerous as people think it is, then winter backcountry travel in continental climates would be much more dangerous than it actually is. Facets and surface hoar dominate the statistics for fatal avalanches that involve the persistent forms; I'm not sure where depth hoar ranks relative to facets, surface hoar, and facet/crust combos.

Anyway, here's a quick primer on depth hoar.

* Depth hoar forms at the base of the snowpack.
* Depth hoar grows where it is warmest ( near the ground ) and where vapour supply is highest ( also near the ground ).
* Depth hoar crystals are large because they have a long growth period ( they're the oldest crystals ).

So in that sense, depth hoar crystals are produced by the same conditions that are always required produce large crystals: relative warmth, plentiful vapour, and long growth period.

author=scotsman]Interesting discussion.. I learnt some stuff.


Me too! Thanks to all the participants, and the Paradise regulars who have made great contributions of photos and historic data.

author=vogtski link=topic=17747.msg75158#msg75158 date=1288645293]
I wonder about the rain explanation.  Was this the only slide that day?  Wouldn't rain have likely produced other slides nearby? 

If memory serves there may have been one or two surface sloughs of the light overnight deposition but certainly nothing even close to the depth of the one pictured above.

author=vogtski link=topic=17747.msg75158#msg75158 date=1288645293]
I've noticed over several decades that 'Angel Face' consistently produces large glide cracks each Spring exactly in the area where this slide occurred, when other nearby slopes with similar steepness & aspect do not.  I've always wondered about the cause of this; perhaps there is slightly higher volcanic heat flow in this localized area?

Now that you mention it, Gary, I can recall seeing and even skiing over or under the glide cracks you mention... in the path of the subject slide, albeit much further below the start zone of the slide. I, of course, haven’t had the sense or awareness skills to wonder why they always happen to be at this particular location each spring  ::)
Now I’ll be wondering too :)

Here's what I know
Maritime snowpack
Lee loaded slope
trees and cliff faces holding snow
A warming rain event
a steep slope below without anchors.

Here's what I'm unsure of The term "climax avalanche " Would this apply here or is this term reserved for spring.

Might be interesting to see what's up there after today???

My understanding of a climax slide is one that takes the entire snowpack, so this would qualify.

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2010-10-28 05:07:46