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Base depth reporting?

post #1 of 8
Thread Starter 
As do many people here, I follow the weather all over ski country in North America and find the reporting of base depths confusing. My best example is until a week ago or so Vail & Alta had reported similar amounts of snow for the year, but Alta's base depth was 30 or so inches higher. In this case I know that both report from near mid-mountain. I've noticed similar discrepencies at other areas as well. Why the difference?
post #2 of 8
If you mean: why does Alta have 100+" on the ground and Vail have 60+/-", when they both have had similar season snowfall amounts? A few reasons:

- CO got a lot of early snow, when the temps were still higher and some snow still melted due to the higher sun angles. UT got its snow later and it didn't melt as much.

- CO generally gets its shots of snow in smaller increments. Snow compacts after each storm, and maybe the smaller increments compacted the snowpack more efficiently.

- Both areas have similar densities of snow, so that should be a wash.

- Maybe Vail puts it snowstake in a more exposed location and the snow gets blown away after its counted on storm totals, but not on the snowpack total.

post #3 of 8
Thread Starter 
Maybe the last one Powdr as I've seen the discrepency repeated over the last 3 yrs.
post #4 of 8
Basically, there are lots of things that can change snow depth at the stake. Most areas try to put the stake somewhere that's relatively sheltered and make sure it's undisturbed. What happens, happens...
post #5 of 8
Originally Posted by jgiddyup
Maybe the last one Powdr as I've seen the discrepency repeated over the last 3 yrs.
Was there a discrepancy from the last three years? If you are talking about CO's snowbase measurements vs. UT's in the last few years, there was considerably more snow in UT than CO during those years.
post #6 of 8
I don't know anything about Utah's snow reporting methods but in Colorado all the areas are in an agreement that must be followed in their snow reporting. Wolf Creek was the last holdout and joined the agreement this season.

The base measurement must be at an approved location that fairly represents the unpacked mid-mountain base (ie. no drifting). Also the location must be located in the middle 1/3rd of the lift served terrain.

Because of the new lift at Breck, they could move their weather station up higher and their snow totals and mid-mountain base reports would increase substantially. I've heard that they are not going to do it because they prefer Vail to report more snow than Breck.

Measuring snow isn't as simple as most people think. Snowfall is very localized in the mountains. A location 100 yds from another could get substantially more or less snow. Snow amounts are also dependent on how often you measure. Colorado's official snow totals are measured every 24 hours. A storm that dumps a 10" snowfall in 24 hours can easily be 12" if measured every 12 hours.

post #7 of 8
I would also add the recent round of storms in Utah had unusually high water content. Thus the base added by those storms was more typical of what we get here in the Pacific States.

I track season maximum base depths for some areas, and the ratio of that number to season snowfall is usually about 20% in the Rockies due to low water content. It can be 40% at Mammoth or Mt. Bachelor, where high water content snow combines with high altitude preservation.
post #8 of 8
Thread Starter 
Thanks Tony! And Powdr I was refering to when the areas reported similar total snowfall with a big discrepancy in reported base depth.
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