Wednesday, January 13, 2010

Como and snow melting

I hit up Como again for some intervals (double pole then V2 uphill) and all around skiing. The conditions are very good, but it could use a groom. Coverage is full. The issues are that pole plants are soft in places, that the skate lane is getting pretty well packed (although better with warmer weather) and that someone ran a truck across a couple portions of the Glacier, which really needs a regroom. Hopefully they can take the machine across it before the weather turns too warm. Tonight would seem to be a good night for it, hint, hint.

As far as the snow melt goes, I'm actually less concerned now than I was yesterday for two reasons. First, the models are happier. They've backed up the huge, tropical rain storm idea and now just have us hovering in the mid-30s for daytime highs with very little moisture for a week, and then cooling back down. It's not ideal, but it should only take a couple inches off of our base if it comes to pass. As I mentioned earlier, we've dodged a bullet by having had an inversion lock in cold temperatures at the surface; it's still +10˚C at 3000 feet but 20 at the surface, and it never got near freezing today despite some sunshine. It looks like that pattern should continue, with a bit of warm-up but nothing worse than a few hours at 34˚. With January sun, we can handle that.

Second, I went in to the archives and looked at times that 8 or more inches of snow has been on the ground in January (about 40% of the time). I could find no cases where more than 10" of snow had melted in December or January, and only a couple times when 8" had. Here are some interesting analogs to make me less scared that the snow will disappear (although when February comes around, with its stronger sun and warmer temperatures, anything is possible). I can't think of a good way to graphically show this so:

2008: 8" on Jan 3, subsequent days 30/14, 37/19, 41/32, 37/27, 34/22, 31/13, 35/29, no rain or snow, melted to 4"
2005: 7" on Jan 22 melted to 0, but that took until Feb 6 and required highs of 35, 44, 33, and then later 33/28, 25/29, 26/31, 42/27, 50/31, 51/35. That was the City of Lakes Meltdown. We have four more inches of snow and those were extraordinarily high temperatures in February. In addition, there was far less snowcover that year to our south and west.
1993: 9" on the 30th melted to 5 on February 3, but only after 39/12, 45/34, 42/24, 38/22, 38/20 with no other moisture.
1992: 8" of snow on the 1st, aided by 0.8 inches but also hit with about 1/3" of rain, stuck around despite a week with highs around 34 and lows only around 31 (yes, for the first five days of the year the high was 37 and the low was 31). The snow barely melted despite a couple more days in the upper 30s. This seems like a worser-case scenario for our current situation.
1991: 8" on the 31st melted to 0 with temperatures of 43/8, 48/15, 42/35, 46/32; we are not expecting these types of temperatures and the sun was two weeks higher in the sky.
1989: 8" melted to 0 over two-plus weeks (the 8th to the 25th) with highs of 35, 37, 33, 37 (this took it from 6 to 2; it had settled from 8 to 6 already … our snow pack is rather dense so there won't be much settling) and then meted with highs of 39, 40, 40 and 35.
1986 may be the best analog: 12" on the 9th melted to 8" by the 20th, with temperatures of 42/28, 34/27, 44/24, 40/14, 22/6, 25/14, 34/11, 38/21, 39/29, 35/27, 33/28, 34/31 with no rain or snow. This would not be a bad outcome for us.
1976 went from 9 to 7 with a day at 41 and the next at 35.
1974 is another good analog. After a cold start to the month, 8" of snow on the 14th melted to 6 wth days at 39/16, 38/12, 41/24, 33/24, 34/12.
1973 melted 8" to 4" with 38/9, 46/24, 44/24, 36/25.
1952 melted 10" on the 30th to 5" with 42/30, 38/24, 37/21.

The one issue is that moisture would be a major wild card. There are only a couple of instances of a lot of rain falling on a lot of snow in January, and, while they are both a very long time ago, neither actually killed the snow pack. In 1946 melted 10" on the 4th to 4" on the sixth with temperatures of 38/25, 36/33 and 33/25, with 0.6 inches of rain on the middle day. Back in 1902, a December storm brought 0.75" of rain (and 3" of snow) but only depleted the snow pack from 10" to 4" despite 35/17, 34/15, 36/34 (with the rain and wet snow) and 36/28.

So the gist of what I'm saying is that to melt more than 10 inches of snow would require weather so extreme that we've never seen it before. A run-of-the-mill January thaw may eat away at half our base, but to lose more than 8" of snow in January is historically unheard of. Now that the three-inches-of-rain-with-embedded-thunder storm has worked its way off the models, it looks like we'll have a week in the 30s. That we can deal with.

The latest model run has significantly cooler weather in the next week—if it verifies I'd be surprised if we hit freezing more than two days, and then two warmer storms—with some rain or perhaps a lot of wet snow—the week after. So, who knows. If I had to predict, I'd say we have 6" of snow on the ground at the end of the month, with good skiing at most Metro locations and great skiing in Elk River (they are starting with more and they keep snow so damn well).

Ski on.

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