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Water content in snow

post #1 of 15
Thread Starter 
I am curious to find out if anyone has any idea on what the average water content in snow is around US/Canada.

In Australia I was told that water content in snow is usually around 50%, but this season it was around 30% due to the drought.

Also before snow can be classed as 'powder' does it need to be of a certain water content. I would doubt that Australia would ever have true powder snow.

post #2 of 15
The water content of snow is usually 100%. Except in northern New Jersey, where there is usually 10-20% pollution
post #3 of 15
I would say that the consistence of snow depends not so much on water content as it does the temperature and humidity of the air around it as it falls. Snow that falls in higher temps is usually wet and heavy, (I.E. my "snow") and as the air gets colder and drier, the snow crystals grow lighter and finer. thus producing good powder. Any science to back up/disprove my disjointed ramblings?
post #4 of 15
Hi Dorzy,

You probably won't get a lot of discussion on water content in snow because it is a matter that doesn't get the kind of PR it should. Most ski areas would not like for people to know much about the quality of their snow because there isn't much that can be done about the quality in terms of lightness or water density.

I think the comments about temperature and available moisture in the atmosphere are probably correct, but there are some very technical features to add in that make for some astounding differences in snow density. ...Maybe PhysicsMan will weigh in on the subject with his always amazing views in the deep technical realms.

The lighter snow here in North America is likely in the 10% and below moisture content. Alta has made it a point to compile data indicating that its average snow density is in that range. http://www.altaskiarea.com/snow.html

Most of the high interior rockies will have snow near that moisture content, with the coastal regions on both sides of the continent having significantly higher averages. The lightest snows I have encountered are in the high Canadian rockies where fast moving Spring storms occasionally drop snow with a density near the 3% range. It is an absolute delight to play in, and will spoil you for other snow qualities that some consider to be 'primo'.

Those 30% and 50% numbers sound pretty high. You have to remember that 100% would be total water with no air space, so 50% sounds like some form of sleet or such. If your natural snow is of a quality that appears better than the man made variety added in for consistency on the ski runs, it is likely quite a bit better(in terms of moisture content) than the numbers you were told suggest.
post #5 of 15
As far as "Powder" goes, usually anything untracked is called powder no matter how much water content.
post #6 of 15
Tony Crocker's website has some empirical data on this measure of snow quality. See http://members.aol.com/crockeraf/snoqlnet.htm. Based on his analysis of 10 western resorts (+ Mt Washington NH), Taos had lowest water/snow ratio @ 6.2%, Alpine Meadows (Mt Hood OR) had the highest @ 15.7%.
post #7 of 15
Your question about a US/Canada water content average is extremely general, and, to be honest, somewhat hard to answer. It’s one of these cases where the variance is as large as the mean. In addition there are substantial definitional issues whenever you talk about any average.

For example, I often hear people throw around the statement that “Colorado snow” averages about 7% water, but they never say if that number is just for the high country ski resorts, for all of Colorado, for just a couple of months during the peak snow/ski season, for the entire year, etc. Obviously, there are a lot of factors that have to be nailed down before you take any average water content number at face value. When you ask about such a large geographic area as the US & Canada, there is even more variability introduced because of the wide range of altitudes, micro-climates, major weather influences (e.g., “lake effect snow” vs. continental climates), etc.

There is even a huge variability in water content of snow falling in any one particular location. I’m sure that in a season Summit County sees everything from obviously dense forms of frozen water like sleet and hail with nearly 100% water content, graupel and more normal snow with intermediate water content, all the way down to the 3% dry, light powder of skier’s dreams. The marketing departments of the western ski resorts would love tourists to believe that nature cranks out 5% snow on a conveyor belt, day in and day out, but unfortunately, a smidgen of variability does happen in the real world.

If you are interested in pursuing this topic further, there is an astonishing amount of info available on the web about snow water content. A search in Google using { snow “water content”} turned up something like 27,000 hits, most of which seemed pretty relevant. A search in Google Groups using the same strategy turned up another 800 hits in the discussion groups.

The info available ranged from the local weatherman providing relatively simple definitions and explanations (e.g., http://www.jsonline.com/weather/wtmj/snowwater.stm ) , all the way to on-line readouts of specific snow gauges, plots over time, theoretical papers, etc. In reading over such material, be careful to distinguish between the water content of snow that is falling (or has just fallen) from the water content of the settled snowpack, a quantity of considerable agricultural importance. Also, from a skier’s perspective, realize that rate of densification after the snow hits the ground is extremely important. It does no good if 7% snow is coming down, but it turns to mashed potatoes in the first 15 minutes.


Tom / PM
post #8 of 15
As a long time skier, I love fresh so have always been fascinated by understanding why it ends up the way it does after any storm. When it comes to fresh snow quality there is and always has been an enormous amount of BS. Don't believe most of what you will ever hear or read. Ski magazines and resorts are certainly the worst. And most skiers never bother to understand much whatever their experience or level. The Tony Crocker web site has been the only reliable information for the public on that for about a decade now.

Some of the Snotel, CDEC, etc remote satellite sensors accessible on the web also provide both precipitated water and snow depth data which together one can derive an estimation of the water content from. There are two remote satellite weather sites near my usual season pass Tahoe area. During storms I am always checking the internet before heading up to jump the fresh. Most of such sensors provide hourly updates to their totals. The two most important are the "tipping bucket" which measures precipitation and temperature. If it is below 34 degrees in is likely accumulating as snow. Snow will be various degrees of heavy (aka wet, cement, concrete) until the temps get below about 28. A lot of the Rockies snow falls when temps are in low twenties whereas upper elevation West Coast snows are more often in upper twenties. Snow quality for powder skiing of course get better with lower temperature. Just a few degrees makes a huge difference. That is why elevation is supremely important even within the same resort. Temperature on average drops about 3 degrees per thousand feet of elevation. Get to know resorts with higher elevations and you are on your way to knowing where to ski powder.

There are more things that effect powder besides temperature. Particularly wind which can pack the snow surface layer into dense slabs aka crust. The colder the snow falls the less it will do so. That is why powder skiing is often best down in trees and lee side gullies where the wind is lower. Once sun comes out of course it obviously negatively effects quality. Also details about the cloud temperatures, altitude and resulting snow crystal types and the humidity of the air through which the snow falls.

One thing is certain which grates against a lot of popular BS is that when the temperature is below 20 degrees F, wind light, and it is dumping hard, no matter where you are Rockies, West Coast, or East Coast, the powder will be fabulous. A snow crystal has no way of knowing it is it just happens to be over Alta. Anyone trying to argue snow is always better one place versus n another is simply blowing hot air. What is true though is that those conditions occur in places like Alta way more. -dave

[ December 09, 2003, 11:12 AM: Message edited by: dave_SSS ]
post #9 of 15
Thread Starter 

I was chatting with a guy who works with the Snowy Hydro Scheme in Australia who measures water content in snow, and he told me that water content is usually around 50% which to me sounded high. Obviously, the farmers here prefer more water content. So I am looking forward to skiing in the Rockies in Jan-March next year to experience nice, dry snow!
post #10 of 15
I have heard that the humidity of the air the clouds pass through also has an effect on the water content of the snow. The facts seem to support this. Utah resorts average around 8% water content the clouds pass through the deserts of Nevada and western Utah drying out all the way, Colorado ski resorts average around 7% in part because the air dries even further as it passes through Utah. Although you also have to consider how much snow resorts get while Colorado ski resorts average 7% water content they also get around 250 inches of snow while Mt. Baker has a high water content 15% it gets over 600 inches of snow a year. so It becomes a question of quality or quantity.
post #11 of 15
I've read that old theory about the Great Basin air "drying or baking out the moisture". Fair amount of truth in it but it is way more complicated than presented. Lots of gobbledeguk information at the NOAA sites if you can find it in thier labyrinth.

Here is a technical thread with a section about "snow water equivalent". Just go to section 5 last paragraph and look at the 3 graphs from Utah. Obviously the SWE ratio to snow depth varies considerably from storm to storm. Not a strong correlation with ground temperatures. A comment therein in effect says that is because the conditions up in the clouds. ie temperature/dewpoint/altitude/layers etc, are probably more an issue than the lower atomosphere snow falls through. Of course getting that data high in the atmosphere is difficult. In any case it shows Utah gets good dry cold snow and they get wetter snow too. Just more often dryer and fluffier.


Be sure to check out these brief snowflake movies:

[ December 10, 2003, 10:58 AM: Message edited by: dave_SSS ]
post #12 of 15
I suppose you could get a good idea of the moisture content by packing a small bucket as tightly as you could with snow, then melting it. This would give you at least an approximation of how much water was in that particular sample.
post #13 of 15
Originally posted by Dorzy:
I was chatting with a guy who works with the Snowy Hydro Scheme in Australia who measures water content in snow, and he told me that water content is usually around 50% which to me sounded high...
I don't know what the "Snowy Hydro Scheme" is, but it sounds like he is dealing with well consolidated old snow. As I said in my post above, one must be very careful to distinguish between newly fallen snow that has not yet started to pack down (ie, the stuff skiers interact with), and the "snowpack" that he is probably dealing with. It is not at all surprising for snowpack to be 50% mid-season.

Originally posted by Zacman1987:
I suppose you could get a good idea of the moisture content by packing a small bucket as tightly as you could with snow, then melting it. This would give you at least an approximation of how much water was in that particular sample.
The procedure you suggested would indeed give you some idea of the volume of the water in your particular snow sample. This procedure would be similar to heating the sample and completely melting the snow, and then measuring its volume. Unfortunately, the volume of snow that is packed but not melted is always quite a bit larger than the volume of the melt water because of the unavoidable air spaces. Unless time is a factor, why not just let the snow in the bucket melt to get an accurate number for its final volume?

Obviously, the issue of most interest to skiers is the density of the snow as initially sampled before it is packed down, so, in addition to the measurement you suggested, one also needs to have a measurement of the volume of the snow as initially loaded into the bucket, before it was packed down. With both numbers in hand, you can then form the ratio and get the desired quantity, the relative density, ie, X inches of snow to one inch of water.

Tom / PM
post #14 of 15
australian snow has the highest water content, I have been told. It's the wettest thing you can get before actual water. Try impressing and aussie with stories of Sierra Cement some time...you won't get far.
There was an interesting study released some years back, to which I do not have a link, where someone measured how quickly the snow packed down under its own weight after falling. The Oz readings taken at Spencer's Creek saw healthy snowfalls reduced to few inches in very short space of time, I am trying to remember who had the driest/lightest...it wasn't Utah, oddly enough. might have been Hokkaido or somewhere.

The Snowy Mountains Scheme is one of the wonders of the modern world. They got the rivers at the highest mountains, and dammed them for hydro power, and reversed them to take water to the dryer land inland. Some also reckon it made made our snowfalls less heavy, with more rain, and warmer/shorter winters.
post #15 of 15
Thread Starter 

Thanks for that confirmation. This is why I want to go to the Canadian Rockies to ski!

The following is an interesting article I found on the net since posting this topic. In relation to the definition of 'powder snow' it says "the last fall of real powder snow fell in Australia in 1803"!!

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