Building the Colorado snowpack

Random thoughts...

I was talking to my buddy Ethan on the CB SP yesterday and he had an interesting story for me. Patrol had dropped some two pounders on Horseshoe and then were on the adjacent run ruby chief later on (this run is groomed normally, but hadn't been yet) and had a settlement that remotely triggered Horseshoe. So, things are solid enough to not slide when bombed, but at the same time can be triggered remotely from a shallow slope 200ft away. Talk about easily getting a false sense of security...

Microclimates... Crested Butte ski area is well known for its' donut hole and lack of snow, and yet 10 miles or less away in the Irwin area and Paradise divide, double the amount of snow falls. Which is why I have a snowmobile so I can access these areas which are usually deeper and that oftentimes means safer. Temp-wise, I live in Mount Crested Butte, which is always 10 degrees warmer than CB, which is always 10 or even 20 degrees warmer than Gunnison. Lots of the arctic fronts won't even make it over here at all (I've talked to my parents in Genesee (that's how it's spelled, Zappa :D ) many times when an arctic front makes it colder there than here. Locally, it's one of the reasons that I never venture into Taylor park, since it is always colder and dryer there and therefor often more dangerous.

It sucked watching how hot it was outside today. And since the last storm, it's actually getting cold at night now. There are two really weak storms in the 7 day forcast. The pessimist in me was pretty bummed out today about the future of the snowpack.

Zappa, Colorado's weather is about as variable as Zappa's choice in genres for music. ;) Without question, the terrain creates microclimates and i think goldenboy makes a good point with the CB doughnut and just to west paradise divide often gets the most snow in the state.

The long term forecast is pessimistic, but thankfully it is only November. And the longer range forecasts, like I said, are of low confidence do to differences in models and tools available at the time they were issued.

Regarding variability-
This tool is very useful re: snow data - snow depth, snowfall, etc.

http://www.nohrsc.noaa.gov/interactive/html/map.html

Quote:

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Originally Posted by NWS ANTI JINX

SCREAMING MESSAGE...DESPITE VARIOUS MODEL
SOLUTIONS...LOOKS LIKE THIS WILL BE A SIGNIFICANT WINTER STORM AS
ALL MODELS AGREE THAT A COLD LONG WAVE TROUGH WILL MOVE ACROSS
COLORADO MONDAY NIGHT AND TUESDAY.

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Models have been trending stronger with this system which is always good.

Since we've got all these links going on... I just dig the ones here for satellite anamations. Especially the 4 km Vis and the 16 km vapor and thermal.

http://www1.cira.colostate.edu/ramm/Rmsdsol/main.html

one of my favorites @ Squall especially like the forecast loop and the sat/jet (past) analysis loop.

After a year my laman's rule of thumb is if we're getting snow forecasts but the jet is not over us = small if the jet's there too = big. There's more to it but that's a basic one.

You guys may have already found this site but http://www.mountainweather.com/ is pretty good. Their computer models, especially the UCAR GFS one, are pretty accurate and let you track precip, wind speeds at different levels and lots of other stuff.

surprised no one has commented on the current conditions after this storm.

havent really read\heard much myself and havent been anywhere near the mountains in a couple weeks so I dont know.

to start
hows it bonding?
how does everyone feel about the really cold weather coming up?
was the new snow a little too much for the old pack in places?
anything else?

Quote:

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Originally Posted by pechelman

surprised no one has commented on the current conditions after this storm.

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iskibc had to work and the rest of us don't ski :) :FIREdevil :eek: :D :D :D

Quote:

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Originally Posted by pechelman

surprised no one has commented on the current conditions after this storm.

havent really read\heard much myself and havent been anywhere near the mountains in a couple weeks so I dont know.

to start
hows it bonding?
how does everyone feel about the really cold weather coming up?
was the new snow a little too much for the old pack in places?
anything else?

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I haven't been out since Thanksgiving but here in south Sawatch it doesn't look like we got very much. Monarch reports 10" storm total and a 31" base. I'm thinking there generally may be a lil' less. The snow that was on the ground had been heavily TG effected prior to the storm and with this arctic air in place I expect more faceting at a pretty fast rate over the next few days.

A report from a friend about the Wolf Creek BC (the area picked up 34" storm total reportedly, bringing the base to near 50") says the the east side lower elevations where the powerline crosses the road may finally have enough base - though she said there were still no tracks coming out. I'm thinking of heading down there for a tour on Sunday.

So I feel that central and south central have a bit more depth hoar base than we've had over the past few years. I would still favor some big loads to set a cycle in motion to clean out lots of places and just start a build over. The CAIC report for Nov 29th mentions this "cleaning" process.

Quote:

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Originally Posted by CAIC

SNOWPACK:
Central Mountains: Poor visibility and tough travel conditions have limited what our observers can see. The folks who have gotten out report lots of collapsing and cracking—excellent indications that the snowpack is just looking for an excuse to avalanche. Storm totals of almost 2 feet in the Elks and southwesterly wind mean slabs formed on north, northeast, and easterly aspects. Underneath the slabs, the old snowpack was a mix of crusts and facets. The old snow makes a very poor foundation that will just support the new load. The snowpack will be very tender and sensitive, and avalanches will be easy to trigger. The snowpack is not going to stabilize quickly, unless avalanches clean out the rotten snow at the base. Be cautious venturing into or below avalanche terrain. Cracking and collapsing are obvious signs of a snowpack ready to avalanche. Do not ignore them.
In the Sawatch Range, storm totals were closer to 1 foot. With less snow loading to older snowpack, conditions will be less sensitive and less dangerous.

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I'll have a shot - been out 3/7 days last week. Sat, Tues, Wed.

Quote:

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Originally Posted by pechelman

surprised no one has commented on the current conditions after this storm.

havent really read\heard much myself and havent been anywhere near the mountains in a couple weeks so I dont know.

to start
hows it bonding?
how does everyone feel about the really cold weather coming up?
was the new snow a little too much for the old pack in places?
anything else?

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Variability seems to be the word - hearing CAIC talk about it. Zappa's talking Depth Hoar. Up north i-70 corridor on north - esp steep and lower elevation stuff the base is much Faceted. On south stuff - esp where lots of sun and/or deep drifts I've seen pretty solid underlayer - although rotten where thinner.

Overall I think its lower danger than can normally be expected at this time of year with a storm cycle like this, but so much variability means you gotta play it as you see it....

http://geosurvey.state.co.us/Avalanc...0220061444.jpg

I was at Berthoud touring out yesterday - saw lots of variability - some places deep and consolidated and many others where its inverted and rotten.
Skied SE/E face in nicely consolidated w/ 0-24" of fluff on top. Also saw E facing cornice naturals that had run.

West face at/below treeline previously untouched was 18" of powder on top of bottomless 30" base. If it slabs out later on top it could easily create the ingredients for collapse. Sometimes I'm more afraid of steep below treeline terrain than steep above treeline b/c of the tendency to rot out underneath where thinner.

Also there was a slippery surface hoar that got prob melted out on sunnier aspects, but remained on northerly to higher east aspects that may explain the N-E tendency to slide now.

Dug a pit at ~ 11,700', NNE aspect, 30 deg. slope, N. end of Sawatch Range in Eagle County.

54" total snowpack, facets comprise bottom 6" at least, fist hardness and relatively uniform crystal size. One finger hard layer at new snow interface approx 18" down. No cracking, whumphing, settling, or anything observed on steeper rollovers. Surprisingly good stability, and fucking deep ass turns.

I'm begining to hear the "mid-pack" phrase. Anyone want to talk about what that is?

...or, how 'bout "bridging"?


Here's a spooky close call from the CBAC obsevations page

Quote:

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Originally Posted by CBAC obs page

December 3 Slate River

Schukyill Ridge skier triggered avalanche about 400' wide, 3 feet deep and almost full track. Said he "skied over a
steep roller 100' down from the top and felt the snow get funny. Skied left to a tree island of safety and turned around to see everything above him moving already. Broke around the tree island he was at, and then back underneath it encompassing the whole bowl except where he was standing. Continued on to Coney's and Snodgrass with no other
activity.

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Wind, Wind, Wind.

Yesterday's tour near Guanella Pass was a story of wind. Windscour much above Treeline other than steep east/SE aspects and below treeline. There varying slabby and punchy windcrusts. Rotten at the bottom anywhere thinner than 30" deep.

I really hate the wind - creates a) extreme variability in depth, b) windslabs prone to slide, c) nasty wind crusts.

random question and observation

the past couple snows here in denver have been sticking around much longer than usual. Normally it seems the snow falls and it all melts the next day. Is this an indication of anything up in the mountains? Or is it just a factor that the snowfall here has been a bit warmer\wetter snow than usual or something else?

Or have I just not lived long enough here in CO to realize that the snow usually does stick around this long in contradiction to the small sample set of data that I have from only living here 2 years?

It still seems unusual to meet that a lot of the stuff I drive by going into work still have significant snow coverage....from the flat plains north of castle rock to a whole bunch of east facing hills just below the foot hills.

I will say its been freaking crazy windy in comparison to what Ive seen in the past 2 years. (esp Thursday night)

Right off the top of my head, I would say you are right to think that the snow usually melts pretty quickly along the Front Range. In the 8 years I have lived here most of it was in Boulder and even the biggest snows usually melted quickly. I would guess it is an indication of colder temps after a storm. Those colder temps(which we have had in the mountains too) usually delays and/or slows bonding of the new snow to the older snow, which in turn can slow stabilization of the upper parts of the snowpack. I have been riding the lifts a lot recently so I don't know how true this is in the bc but some of the recent avi reports from CAIC and the RFAC seem to indicate this as well.

I would say that it is more indicative of abnormal snowfall down here coupled with pretty normal cold temps. In the mtns things are seasonably cold.

Quote:

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Originally Posted by smitchell333

Wind, Wind, Wind.

Yesterday's tour near Guanella Pass was a story of wind. Windscour much above Treeline other than steep east/SE aspects and below treeline. There varying slabby and punchy windcrusts. Rotten at the bottom anywhere thinner than 30" deep.

I really hate the wind - creates a) extreme variability in depth, b) windslabs prone to slide, c) nasty wind crusts.

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I hear what you're saying. Especially above TL combined with east of the divide. While it can make a 4" snowfall thigh deep in other spots through transport (which is frickin' awesome), it's also the culprit creating the loading zone where the avies tend to reside. My experience/education here comes from many years skiin' loveland, home to lots of wind, but in a "controlled" environment.

Wind and it's effect is also the very reason I spend most of my BC time below TL or head to ranges that aren't as prone to the endless pounding from the wind. ie. San Juans.

I used to (and guess I still do) have kind of a theory about the effects the wind has on the individual snowflakes and hence the way that would build into the pack - to a certain extent. What I've been thinking/observing can be witnessed by driving your car or getting out and walking/slipping around on your feet in different locals. Note: In these observations I'm generally speaking of observations during a storm.

Here's what I noted: Up around Loveland I think the flakes get broken down and are likely to be a "smaller" grain size and prolly pack denser. - Cooler temps in general may/prolly play a part here too. I noted that tracktion, in the car and on foot, was pretty good around there. Like small sharp grains.

Now I've been hanging around the Monarch area and when it snows it's generally much calmer, (as compared to Loveland area). The roads are much slicker and the way the snow gets under tires and feet is like an ice rink on a slope. And the pack I think is less dense (blower). Like big flat slipery plates.

In the Wolf Creek area, home of the big overnite dumps, and warm daytime temps, you can almost watch the settlement it's so fast. Here snowfall is mixed a lot but generally fluffly I think due to less wind. Graupel, rime, columns, flakes... all kinds of snow in there. And I think temps play a roll as they seem somewhat warmer.

I'm sure there are other factors, but I just thought I'd throw these observations up.

Some factors: Northern CO seems to get storms out of the PNW, whereas southern CO seems to do better with storms coming from southern CA and Baja regions. Moisture content. Orographics, etc.

So, I guess with and without wind, as far as the pack goes, we get soft and hard slab development. And I the structure of the individual flakes and the way they make up the build I think is pretty heavily impacted by wind.

Well, now I'm thinkin' about all the kinds of crystal formations out there, and what effects they can build into the pack. You know, structure wise like densities and how they might bond to each other.

So, I'm gonna borrow a bunch of great close ups from http://www.lpsi.barc.usda.gov/emusno...ison/comp1.htm and qoute what they say for each pic. While some of these may not pertain to Colorado's pack, I'll put 'em all in cuz they're kinda purdy.

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Comparative Images of Snow Crystals
This series of scanning electron micrographs represents newly precipitated and metamorphosed snow crystals. The small circular inserts are the "classical" light microscopic images that have been published by Nakaya, Bentley and others. Magnification figures (i.e. 450x) that are indicated on the micrographs are only true for 8" x 10" images. Bars are accurate for all magnifications.

http://www.lpsi.barc.usda.gov/emusnow/comparison/11.jpg
The image that most people have of a snow crystal.

http://www.lpsi.barc.usda.gov/emusnow/comparison/10.jpg
A common snow crystal form; note the double sheet structure.

http://www.lpsi.barc.usda.gov/emusnow/comparison/12.jpg
The column forms across a wide range of cloud temperatures and has many variations including the bullet.

http://www.lpsi.barc.usda.gov/emusnow/comparison/13.jpg
The needle crystal is often associated with heavy snowfall in the Northeastern United States.

http://www.lpsi.barc.usda.gov/emusnow/comparison/14.jpg
This form has been difficult to image using light microscopy whereas LTSEM reveals it's true 3-D nature
The crystal type is sometimes indicative of a temperature inversion layer in the atmosphere.

http://www.lpsi.barc.usda.gov/emusnow/comparison/15.jpg
A combination of two crystal forms; the Japanese Tsuzumi is an unusual variation.

http://www.lpsi.barc.usda.gov/emusnow/comparison/16.jpg
The side plane is only one example of irregular crystals which include broken crystal fragments and abnormal growth features.

http://www.lpsi.barc.usda.gov/emusnow/comparison/17.jpg
Sometimes the original crystal shape coated by rime is apparent, sometimes only an amorphous blob is evident.

http://www.lpsi.barc.usda.gov/emusnow/comparison/18.jpg
Ice pellets commonly occur with other crystal forms near the freezing point.

http://www.lpsi.barc.usda.gov/emusnow/comparison/19.jpg
Small hail that has been fractured to show internal structure.

http://www.lpsi.barc.usda.gov/emusnow/comparison/26.jpg
Sampled shortly after deposition on snowpack.

http://www.lpsi.barc.usda.gov/emusnow/comparison/27.jpg
This wind-packed snow from Alaska's North Slope resembles a 3-D jigsaw puzzle.

http://www.lpsi.barc.usda.gov/emusnow/comparison/28.jpg
The original form is evident but rounding has occurred.

http://www.lpsi.barc.usda.gov/emusnow/comparison/29.jpg
Rounding of original shape is more pronounced.

http://www.lpsi.barc.usda.gov/emusnow/comparison/30.jpg
Some nearly distinguishable forms exist and sintering between grains has started.

http://www.lpsi.barc.usda.gov/emusnow/comparison/31.jpg
Small rounded grains with no original crystal forms evident.

http://www.lpsi.barc.usda.gov/emusnow/comparison/32.jpg
Evidence of both rounding and faceted growth exists.

http://www.lpsi.barc.usda.gov/emusnow/comparison/33.jpg
Initial layered forms are present with faceted crystals.

http://www.lpsi.barc.usda.gov/emusnow/comparison/34.jpg
Layering and hollow interior characterizes this unusual depth hoar crystal.

http://www.lpsi.barc.usda.gov/emusnow/comparison/35.jpg
Another layered and hollow depth hoar crystal with little evidence of bonding.

http://www.lpsi.barc.usda.gov/emusnow/comparison/36.jpg
Obtained in a portion of a melting snowpack with little free water apparent.

http://www.lpsi.barc.usda.gov/emusnow/comparison/37.jpg
Obtained in the surface layer of a melting snowpack with much free water evident.

http://www.lpsi.barc.usda.gov/emusnow/comparison/38.jpg
Firn from South Cascade Glacier.

http://www.lpsi.barc.usda.gov/emusnow/comparison/39.jpg
Glacier ice from South Cascade Glacier.

Zappa - some interesting pictures. I think a lot of what's important about the snow crystal structure is what it means for that snow's role in the pack. If its loose and no bonds between crystals it can mean little slab avy danger if its the top layer - ala untouched powder. But if loose and slippery and no bonds on the bottom such as depth hoar and a tense slab lays above it - whuuummmppffff.

Anyone get out today? What aspects above treeline are skiing OK?

Just going to post an observation... Was hiking and skiing in the side country in the Holy Cross wilderness area and saw some amazing (both amount and size) surface hoar. Fun to ski, but could set up as a poor layer once it gets energy on it.

12/09/06 - The snowpack on the north facing aspects around the Montezuma area had large crystals of surface hoar. The entire snowpack was sugar above and below treeline.

great shots FZ - that's a good resource

Love those crystals, Zappa.

You in CO yet mike?

ferry leaves at 0245 tomorrow morning

we'll be on the road from Bellingham Dec 15th, and will likely be in your neck of the woods around the 20th or so.....

meadow skipping?

Touring in the Monarch Pass area on 12.10 I found 10-15" of total hoar to the ground. Wind deposited pockets existed with 20ish inches, still hoar. Very thin crusts on isolated aspects. They definitely need snow down there.

Quote:

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Originally Posted by MakersTeleMark

Touring in the Monarch Pass area on 12.10 I found 10-15" of total hoar to the ground. Wind deposited pockets existed with 20ish inches, still hoar. Very thin crusts on isolated aspects. They definitely need snow down there.

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On what aspects/area did you observe these conditions? I was at the ski area on Sunday and Monday. They did get a decent acummulation between Sunday afternoon and Monday afternoon.

Near and at treeline around and below the cat terrain.

Lots of wind and steady small accumulations this week near Loveland resort resulted in good, though highly variable conditions this AM. ~ 12-15 inches of new snow in sheltered areas with significantly more in wind loaded gullies and rollovers with sensitve soft slabs lurking...at least they were soft below treeline, didn't get above treeline to see if they were any more insidious:

http://i5.photobucket.com/albums/y18...0/100_0095.jpg

Highly variable coverage too with lots of logs still lurking just out of sight. Be careful out there, particularly this weekend if this storm drops a big new load on us as the newer snow wasn't bonding all that great and there were a couple of times where we were wallowing in nearly full pack facets.

Quote:

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Originally Posted by telemike

ferry leaves at 0245 tomorrow morning

we'll be on the road from Bellingham Dec 15th, and will likely be in your neck of the woods around the 20th or so.....

meadow skipping?

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That'd be fun! drop me an email or PM or just post somewhere obvious as the time approaches.

pde20, is that A tow? Coming down to the interstate behind the lodge about even with LL's parking lot. South aspect then if it is?

http://i5.photobucket.com/albums/y18...0/100_0095.jpg

Nice shot BTW:D

Quote:

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Originally Posted by FrankZappa

pde20, is that A tow? Coming down to the interstate behind the lodge about even with LL's parking lot. South aspect then if it is?

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No. East aspect ~ 11,000 ft

trelease?

I'm just posting b/c as much as I enjoyed the crystal photos, it takes forever for this page to load. ;)

Quote:

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Originally Posted by goldenboy

I'm just posting b/c as much as I enjoyed the crystal photos, it takes forever for this page to load. ;)

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Hah, i was thinking the same thing before i read your post, so here's another

Well hell! If we get just 4 more posts, wait make that 3, then we can go straight to the next page.

Quote:

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Originally Posted by pde20

No. East aspect ~ 11,000 ft

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Ohhhhhhhh.... So you were below LL and LL's parking lot.;)

(2 more)

Watch... some body will "quote" this once we get a new page.:rolleyes: :eek:

(1 more - who's it gonna be?)

To the rescue for new page.