Building the Colorado snowpack

[FrankZappa]

Just saw yesterdays (11/16/06) CAIC report for central mountains... Yikes! I'm impressed. After being up there a week and a half ago Homerjay were talkin' about the remote trigger effect - especially with hard slabs formation that we witnessed. I had to quote it here.

SNOWPACK DISCUSSION:
Central Mountains: The Central Mountains received the most snow during the last storm. As a result, there was some impressive avalanche activity in the alpine areas. There were no new natural avalanches reported today, but yesterday near Independence Pass skiers remotely triggered avalanches over 500 feet way. The crown faces ranged from 1 to 6 feet deep. All slides ran on weak faceted snow below the new snow or near the ground. There have been no new avalanches reported today, but the conditions remain tricky on wind-loaded slopes that are near or above treeline.

[DanKo]

Yikes is right. Stayed to mostly lower-angle aspects and trees yesterday. Snow was definitely wind loaded with a slabby feel, but otherwise no other real danger signs where I was (LP).

CAIC's reports over the last few days have certainly given me the willies, though...

[climb2ski]

if the trees are wide enough to ski they are wide enough to slide....

[DanKo]

^^^Truth, but they (generally) carry much less risk.

[Rontele]

Here is me getting real cynical looking at the long range forecasts and thinking that we won't get any big storms until the 1st of December. Sad, but possibly VERY TRUE. With the warm temps also expected, what do you all think this will mean for the snowpack?

[FrankZappa]

Here is me getting real cynical looking at the long range forecasts and thinking that we won't get any big storms until the 1st of December. Sad, but possibly VERY TRUE. With the warm temps also expected, what do you all think this will mean for the snowpack?

This sounds like more of what we had a week or so ago. (right?) So I expect more weakening of the pack. It's still not that deep, and we're obviously seeing that the bottom has gone to crap, so I think the TG will get worse. After all, it may be warmer but at night, especially up high where we're likely to be, it still cold with long nights. Southerly exposures may develop some crusts. And along with that prolly some surface & near surface changes. With clear weather generally we see wind too.
So, to summarize, sounds like a typical Colorado pack in the makin'.
When the snows come back again, it'll be primed and ready to go I'm afraid. They'll just be getting bigger and more dangerous.

[Rontele]

This sounds like more of what we had a week or so ago. (right?) So I expect more weakening of the pack. It's still not that deep, and we're obviously seeing that the bottom has gone to crap, so I think the TG will get worse. After all, it may be warmer but at night, especially up high where we're likely to be, it still cold with long nights. Southerly exposures may develop some crusts. And along with that prolly some surface & near surface changes. With clear weather generally we see wind too.
So, to summarize, sounds like a typical Colorado pack in the makin'.
When the snows come back again, it'll be primed and ready to go I'm afraid. They'll just be getting bigger and more dangerous.

I hope I am wrong. Duh. But the models are just stubborn in keeping the trough off the west coast and a large ridge just freaking anchored in the center of the country. Thus any energy that does move inland will just weaken as it hits Colorado. Though moisture may be there with the remnant s of Hurricane Sergio Towards the end of the period, though, the models are far off so confidence in any sort of forecast isn't high. But by then that is already looking at the end of November, etc.

I am keeping a close and watchful eye on the weather.

Selfishly I just want to always dump in Colorado, but since I am gone for the next two weeks, the big snows can wait (though they never seem to) until I come back

[FrankZappa]

Rontele - Post some links to what you're watching please.

[Rontele]

I get all of my forecasting tools from the NWS. Here is the suite of short to long term range forecasts. The maps are easy to read, but not fully explanatory, the discussions are more helpful but can be complicated. Feel free to PM me or post here if you have any questions, etc.

48 hours, click CO then Forecast Discussion for local weather
3-7 for QPF (quantitative precipitation forecast) and to see a daily GFS ensemble of what they are predicting for that medium range period
6-10/8-14 are pretty self-explanatory.

[FrankZappa]

While we're here... Hows about a lil' talk about weather in Colorado.

It's been my conclusion that weather is much the same as the spatial variability that we have in the snowpack. That is to say that it can be completely different just a short distance away - depending on a lot of factors.

Anyone care to chime in on this matter?

For example: Back in the eighties, I lived up above Silver Plume and commuted to Denver. I quickly found out that many, many times the weather was the opposite between the two.
or...
There is the a weird phenonemon (at least it used to) to in the dwellers of the front range (and the rest of the country when it snows in Denver for monday night football) where even the local weather persons believed that if i was snowing in the city it must be dumping in the mountains.
or...
Back when I was doing that commute, every once in a while we'd get one of those brutal arctic air masses that would push down the front range. As I was runnin back and forth I noticed that the cold air would first be in the lower elevations (Denver), but once I got up higher (like Gennessee) it was still warmer. The next day the cold air was up to say Idaho Springs (Yo-Yo flats). The next it would be up to Georgetown. Then finally it would engulf the very hi country.
This is kinda what I think I see in the BIG valleys around the state that are notorious for the frigid temps settleing in the low lands - ie Gunnison or Alamosa - where the temps are recorded and broadcast to us, but that cold air just pours down from the hi country and pools. Much like the temp inversions at Jackson.


So... Lets hear it. What's up with the weather? pros & cons?
What effects are generated from the weather (changes or stable) in relation to our infamous snowpack?

[goldenboy]

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 ) 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.

[Rontele]

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.

[smitchell333]

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

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

[Rontele]

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.

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

[FrankZappa]

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

[lemon boy]

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.

[Joey Joe Joe Junior Shabadoo]

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.

[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?

[lemon boy]

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

iskibc had to work and the rest of us don't ski

[FrankZappa]

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?

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.

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.

[smitchell333]

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

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?

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....

[smitchell333]

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.

[homerjay]

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.

[FrankZappa]

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

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.

[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.