Building the Colorado snowpack

**FrankZappa** · 11-05-2006, 01:34 PM

Update
Early Nov conditions
East Independence Pass on the divide flanks
Ele 10,500 Very minimal amounts 0" - 6", sun baked & recycled.
at & w/n 500-700 ft below T-line, 12"-24", N aspects Drifted and enough to support but expect it to turn more faceted soon, S aspects bare to peaktops.
Above T-line, Lots of wind activity and hard slab development, variable crud.
We did notice a small point release on SE aspect - rocks more than likely.

Monarch district has similar characteristics but a little less snow.

Still is a pack that varies considerably with elevation as goldenboy had mentioned earlier a few weeks ago.
If we don't start getting quite a few good storms soon I expect to see this pack turn to almost complete depth hoar. I was actually surprised it hadn't already. And what we skied was lots of willow bashing with knee high branched still above the surface - which still supported us.

**goldenboy** · 11-05-2006, 07:12 PM

Dawson and friends found a tightly consolidated and frozen base in the San Juans, with some potential for bonding issues in the upper layers for our next storm. Good to hear that the snow there seems to be holding up for the time being. Hopefully some waves start to bulild the pack back up later this week. Check out http://wildsnow.com/ for their analysis of the pack down there.

Also, the Crested Butte Avalanche center is starting up their regular forecasts tomorrow. http://www.cbavalanchecenter.org/

Z · 11-05-2006, 10:24 PM

Im not a snow science nerd, but it seems that we've been building a pretty decent pack here in the front range. Between storms, the warmth has stopped our death hoar foundation to some degree. Usually it's the supercold clear nights that form the hoar around here. Seems like the current pack is super consolidated in almost a freeze-thaw cycle that could turn out to be a pretty bomber bottom layer. Im sure that could change, but personally after the next storm I think most BC is good to go...

**Choke Slam** · 11-05-2006, 11:41 PM

From what I've seen, the snowpack is actually a little tender in Summit county. While the snow was bomber for about a week after the last storm, it seems like the wind has fucked us yet again. Soft and hard slab has formed in a lot of areas. In the pit work I've done, it seems like the slab will break on the layer left from the first storm of the season. Depending on how much snow we get soon, I think we might see an avy cycle. The snowpack is no longer early season-be careful out there. North to east facing aspects are suspect.

**Rontele** · 11-06-2006, 08:36 AM

Originally Posted by Choke Slam

From what I've seen, the snowpack is actually a little tender in Summit county. While the snow was bomber for about a week after the last storm, it seems like the wind has fucked us yet again. Soft and hard slab has formed in a lot of areas. In the pit work I've done, it seems like the slab will break on the layer left from the first storm of the season. Depending on how much snow we get soon, I think we might see an avy cycle. The snowpack is no longer early season-be careful out there. North to east facing aspects are suspect.

The models have definitely backed off on the system for the end of this week. Though I imagine we will get some snow, but not enough to stress the snowpack. But after that the models are hinting at a pretty large trough coming into the PacNW from a L in the Gulf of AK. Too far out to get excited, but it could shift back into a very wet pattern...

**Joey Joe Joe Junior Shabadoo** · 11-06-2006, 09:14 AM

Originally Posted by FrankZappa

Still is a pack that varies considerably with elevation as goldenboy had mentioned earlier a few weeks ago.
If we don't start getting quite a few good storms soon I expect to see this pack turn to almost complete depth hoar. I was actually surprised it hadn't already.

You may be on to something. Let's hope for more snow like we always do. From the CAIC on Friday:

"Most of our observers are reporting the old snowpack to be influenced by the developing strong temperature gradient & turning to small facets. Reports from Rocky Mtn park tell of fairly dense wind compacted snow up to a couple feet deep even on the steeper terrain, generally on southerly aspects. Hodge-podge of supportable layers to some sun crusts. No recent sign of slide activity noted. There is nothing on the near horizon to change the current conditions. " Small is still better than big facets but once it goes to facets(even small ones) it takes a lot more time and energy to reverse the process.

**smitchell333** · 11-06-2006, 02:10 PM

My take is that to date the temps have been relatively moderate ( its been October after all) and therefore faceting hasnt been intensive overall. Now we're getting into Nov and temps will get colder and colder and therefore the Tempurature Gradients stronger = more rapid faceting.

The next 3 weeks are the crux vis a vis faceting.

a) If we get significantly more snow it may very well retard the facet development

b)If snow is minimal or non-existent then we're gonna have a lot of facets.

The high winds have also complicated matters as someplaces there is 0 snow and others deep drifts - therefore the variability of facet development will be high.

**Choke Slam** · 11-07-2006, 01:08 AM

its raining at 9300ft, so yet another interesting aspect to the snowpack!

**homerjay** · 11-07-2006, 09:15 AM

Originally Posted by Choke Slam

its raining at 9300ft, so yet another interesting aspect to the snowpack!

Rain over here in the valley, too, do you know what the snowline was yesterday?

**FrankZappa** · 11-07-2006, 12:06 PM

Originally Posted by Z

Im not a snow science nerd, but it seems that we've been building a pretty decent pack here in the front range. Between storms, the warmth has stopped our death hoar foundation to some degree. Usually it's the supercold clear nights that form the hoar around here. Seems like the current pack is super consolidated in almost a freeze-thaw cycle that could turn out to be a pretty bomber bottom layer. Im sure that could change, but personally after the next storm I think most BC is good to go...

Yeah, I would hope that it does get bomber, but with the dry cycle we've had combined with the still shallow pack, cold nights... Just keep in mind things are bound to be changin' in there.

The Crested Butte Avalanche Center had a reminder on thier site today that I wanted to relate concerning our next system and the load it may put on the pack:

Originally Posted by CB avy center

Higher elevations are still holding snow on northerly aspects but with cold dry conditions we are likely to see the snowpack weaken. South aspects have been supportive but it is melting out quickly. Northerly aspects are seeing facets growing which weakens the snowpack and becomes unconsolidated. The hazard does not usually increase until we see an additional load on this weaker snowpack. South aspects are very shallow but in areas that have blown in especially on easterly aspects you might see a small slab release.

Just sayin' don't forget that things can be changing over a week (more or less) so don't get tempted too easily. I've been reading Vol. 4 of the Snowy Torrents lately and it seems many accidents happened after a dry spell, like we've had, just after the new load. - Nov. ranks right up there. And also, in many areas of the state, as has been said before, there are drastic changes with elevation gain/loss and lots of wind effect (transport).

The other thing I picked up on reading that is the number of slides that had been skied by several people before it let loose - especially when TG was a big factor.

Also they have a good link to Avalanche org's description and a lil' visual on the transformation to facets. Faceted snow Lots of other good stuff there too.

**SV-Stormchaser** · 11-07-2006, 04:03 PM

Originally Posted by FrankZappa

Yeah, I would hope that it does get bomber, but with the dry cycle we've had combined with the still shallow pack, cold nights... Just keep in mind things are bound to be changin' in there.

Over the weekend in Mayflower Gulch I repeatedly found variations within a 20'x20' patch ranging from top-to-bottom facets to bombproof wind slab. Such variability within the same angle/aspect/elevation doesn't give me much faith that we'll see anything close to bomber with the next storms. Beware the false stables...

**shera** · 11-09-2006, 08:40 AM

Originally Posted by FrankZappa

Yeah, I would hope that it does get bomber, but with the dry cycle we've had combined with the still shallow pack, cold nights... Just keep in mind things are bound to be changin' in there.

The Crested Butte Avalanche Center had a reminder on thier site today that I wanted to relate concerning our next system and the load it may put on the pack:

Just sayin' don't forget that things can be changing over a week (more or less) so don't get tempted too easily. I've been reading Vol. 4 of the Snowy Torrents lately and it seems many accidents happened after a dry spell, like we've had, just after the new load. - Nov. ranks right up there. And also, in many areas of the state, as has been said before, there are drastic changes with elevation gain/loss and lots of wind effect (transport).

The other thing I picked up on reading that is the number of slides that had been skied by several people before it let loose - especially when TG was a big factor.

Also they have a good link to Avalanche org's description and a lil' visual on the transformation to facets. Faceted snow Lots of other good stuff there too.

Good info. Thanks.

I love the Snowy Torrents books. Need to look them over again.

**Choke Slam** · 11-10-2006, 08:39 PM

Originally Posted by homerjay

Rain over here in the valley, too, do you know what the snowline was yesterday?

it was raining untill about 9800-10000ft. At that point, snow was sticking to the road. How about in your area?

**El Kabong** · 11-12-2006, 01:15 PM

I was up at mayflower gulch yesterday (11/11) for some mellow touring. Still some good soft snow in the trees. However, seems like the avy danger is probably on the up and up. Definite wind slab, maybe 6 in deep starting to form on the stuff right above treeline. The wind really picked up in the afternoon, probably 30-40 mph blowing constantly. Lots of transport going on, seemed to be blowing stuff onto north facing aspects. Saw one hard slab release in a small pocket on a lee aspect. Looked to be about three foot slab with pretty big blocks, didnt run far as it was a short slope but scary to see none the less. I wanted to take a closer look at it but the wind was blowing so hard I couldnt think so just kept going. With the new snow I would be careful out there.

**FrankZappa** · 11-12-2006, 03:35 PM

Thanks for the reports from around the box everyone.

The following aimed at the "NOT so much experienced" back country traveler But others please chime in.

So, after seeing whats been going on after the last few weeks... What are the predictions for
a) if things keep going the same as the past couple weeks - weather wise
b) what do you expect if we get a big dump?
c) If we do get snow, what would happen if it came in cold and dry and then turned heavy?
vs.
d) Comes in warm and heavy and then turns cold
e) How much snow is it gonna take to load the pack?

**pechelman** · 11-12-2006, 03:58 PM

Weather wise it sounds like 2 systems are moving in for a good chance at a lot of accumulation, especially with the aid of the wind. If the last storm is any indication, it seems like the snow will be heavy. This extended period of clear nights, no snow, and strong winds make me worry a lot of things will start sliding due to this system. As usual its really windy out there but there seems to be a more prevalent wind crust down lower, according to some ski patrol folks at copper I talked to yesterday. He and I were both shocked and scared by the fact that tucker hadnt slid yet this season. Short term, I think this first system might dump a little too much too fast and too heavy and make it pretty dangerous for a while.

Long term, the added base will definitely be great, especially with the next system rolling through a few days after this one ends. If mid winter is going to be a cold and not-snowy as is predicted by this elnino \ typical colorado weather, we'll need it.

**grskier** · 11-13-2006, 11:50 AM

Just driving down from Summit county this morning, you could see a lot of angel fire... I'm sure things are getting going to get loaded from this next storm... tread lightly.

**homerjay** · 11-13-2006, 11:57 AM

Originally Posted by El Kabong

I was up at mayflower gulch yesterday (11/11) for some mellow touring. Still some good soft snow in the trees. However, seems like the avy danger is probably on the up and up. Definite wind slab, maybe 6 in deep starting to form on the stuff right above treeline. The wind really picked up in the afternoon, probably 30-40 mph blowing constantly. Lots of transport going on, seemed to be blowing stuff onto north facing aspects. Saw one hard slab release in a small pocket on a lee aspect. Looked to be about three foot slab with pretty big blocks, didnt run far as it was a short slope but scary to see none the less. I wanted to take a closer look at it but the wind was blowing so hard I couldnt think so just kept going. With the new snow I would be careful out there.

Where did you see the slab release? I was there from about 9-1. Didn't dig a pit, but felt a very funky layer underfoot in everything that was on the exposed face. Looked like the weather was worsening in my rearview on the way out.

Oh, and pechelman, the snow is pretty light and cold thus far, it's snowing steadily at 7500' or so. Not windy in the valley at all, but up high ???

Were you in the group of 4-5 people out there?

**Rontele** · 11-13-2006, 01:09 PM

thanks for the firsthand info jeff. I have no doubts that wind is going to be a big issue with this next storm. But high pressure looks to set in by wednesday, though the models today show some energy overriding the ridge for Thurs/Friday...stay tuned and be careful out there.

Bert thursday seemed to be a bomber pack with dust on top of it. Though there were some shallow releases with a ski cut where the new snow bonded to the windslab. This added weight of the new snow could be enough to set off a pretty widespread cycle, especially in areas where windloading is susceptible.

Did I say be careful out there?

**El Kabong** · 11-13-2006, 04:24 PM

Saw the slab on the north side of mayflower hill, just down from where the cliffs end. I was in a party of 3, 2 guys and a girl. Couldnt tell how fresh the slide was but it was pretty deep though not very big. It broke in a pocket along the ridge that looked like a very obvious wind loading zone.

**Rontele** · 11-13-2006, 04:32 PM

For those who don't get the CAIC forecast

Originally Posted by CAIC

SNOWPACK DISCUSSION
The early season snowpack will get its first good load with tomorrow's storm. Strong winds will form many windslabs near and above treeline. You will be able to find the slabs on northeast through east to southerly aspects, as well as cross-drifted around terrain features and into gullies. The slabs will sandwich weaker snow from Sunday against the old snow.

In the Northern and Central Mountains, the old snow surface was a mix of crusts. On most sun-exposed slopes, the crusts were strong and slick, making a good surface for fast-running avalanches. Shadier aspects have a weaker crust, with weak faceted snow underneath. Avalanches in the new snow could easily dig into the older snow. Small avalanches, including a skier-triggered slide in the Professor near Arapahoe Basin, have run in the new snow. Observers report cracking and easily triggered test slopes, with windslabs already a foot thick.

The snowpack is very thin and patchy in the Southern Mountains. In shady spots the snowpack is very weak and will not support additional snow. Observers report easy shears in the middle of the snowpack, and shooting cracks 50 feet long. Near Wolf Creek Pass, an observer was able to trigger small, two-foot deep avalanches in pockets. The pockets consisted of rapidly wind-loaded snow sitting on a slick crust. One up side of the thin snowpack is that many slide paths are not filled in, and avalanches will not run very far. The down side is an ugly, rocky cheese grater if you are caught. Be caution of any slope that is filled in enough to look like good turns.

BACKCOUNTRY AVALANCHE DANGER FOR TUESDAY:
Northern and Central Mountains: The avalanche danger will rise to HIGH near and above treeline. Avalanches will be likely on north through east to south aspects. Watch for crossloading around terrain features. Below treeline, the danger is CONSIDERABLE. Backcountry travelers will probably encounter slabs on steep terrain. The slabs may be windloaded and easier to recognize, or they may be surprisingly soft and lure a rider onto a slope.
Southern Mountains: The avalanche danger is very dependent on the underlying snow. With either slick crusts or weak facets under the recent snow, the avalanche danger will rise to HIGH. Where the new snow is resting on the ground, the danger is MODERATE, and avalanches will be relatively shallow.

**pechelman** · 11-13-2006, 04:56 PM

to receive these updated by email automagically
go here

http://www.avalanche-center.org/Bull.../avalanche.php

dont even begin to ask me about the stupid commands to reply to that thing.

**pde20** · 11-13-2006, 05:26 PM

Originally Posted by pechelman

to receive these updated by email automagically
go here

http://www.avalanche-center.org/Bull.../avalanche.php

dont even begin to ask me about the stupid commands to reply to that thing.

Better yet, go here:

http://geosurvey.state.co.us/avalanc....aspx?tabid=51

and support the folks that help keep you alive during the winter, you chintzy bastards.

**Rontele** · 11-13-2006, 06:28 PM

Originally Posted by pde20

Better yet, go here:

http://geosurvey.state.co.us/avalanc....aspx?tabid=51

and support the folks that help keep you alive during the winter, you chintzy bastards.

Already made my donation

**grskier** · 11-16-2006, 03:09 PM

A few observations from a quick drive up on SH 7 today:

Holy crap is the snow blowing in and around RMNP. It was even transporting snow (visibly, from SH 7 to Longs Peek distance) below treeline in psuedo clouds. Pretty cool to watch, but sobering at the same time thinking of the loading that was going on.

As always, be careful.