So far so good. The Utah Avalanche Center reports that yesterday's storm produced 13" of snow and 1.36" of water in upper Little Cottonwood Canyon. Storm #2 of the cycle moved in late last night and with warm advection occurring in advance of the upper-level trough, the radar coverage is currently as widespread as it can get. The only areas without returns are areas with terrain blockage that the radar can't see.
In the central Wasatch, I expect continuous snowfall this morning. The trough at crest level is forecast to pass in the early afternoon and should be accompanied by a shift in crest-level winds from southwesterly to northwesterly. Snowfall will be heavy at times and looks to continue through evening. The Utah Avalanche Center anticipates 8-14" through early evening, and that's aligned with my thinking. The radar and model forecasts all point to a significant event.
If you are looking for something to give you a forecast ulcer, then consider the forecast for the Salt Lake Valley. My house is at 5000 feet and I'm currently seeing rain with a bit of snow mixed in at times. MesoWest observations indicate that the freezing level is around 5700-6200 feet (e.g., Mountain Dell @ 5700 ft and the Big Cottonwood S-Curves @ 6235 ft are both 32˚F). The snow level is usually a bit below the freezing level, but can fluctuate with precipitation intensity. This is why I'm sometimes seeing some flakes mixed in at my house.
Will that change? If we look at the NAM time-height for the airport, for example, the freezing level (blue line) sits at about 875 mb through 0Z Sunday (5 PM MST today), maybe a smidge lower than where it is now. The NAM generates a trough structure that "tips forward" with height, so while it produces a crest-level trough passage in the afternoon, the valley trough passage and a more dramatic cooling trend doesn't occur until evening.
Given how poor the snow year remains across Utah I'm surprised that in all likelihood we will actually end up less than a week off from having met the technical marks for a Steenburgh Winter. Granted, not complaining- it's been fun (and a relief) to watch it pile up so quickly in the last several days since the NW track started. That said, we are still below 100% at every SNOTEL station in the state and the Snowbird station is 71% with data reporting thru EOD yesterday. I don't recall being so close to the mark before while having such a poor water year... is there a snow total vs SWE disparity that's greater than normal? Not sure why it looks so good on paper but not yet in the proverbial rain buckets.
ReplyDeleteAny simple index like "Steenburgh Winter" is bound to have shortcomings, and there are many! First, it's only a snapshot at one time, and there are a lot of pathways to get to 100" by Feb 10 (or not get to it).
ReplyDeleteSecond, the water equivalent of the snowpack is a better measure to use than snow depth, since it is a measure of the mass of the snow, whereas snow depth is strongly influenced by density. This year, we've had a lot of snow in the past week, and that has helped us get to 100" with lower snowpack density and water equivalent.
The concept of Steenburgh winter was a fun one, but scientifically, it doesn't necessarily pass peer review...
Jim
Ha, yeah I'm not looking for it in any AMS pubs to put it one way, but it's generally been a decent rule of thumb for as long as I've followed the blog.
ReplyDeleteExperienced one flash of lightning last night by our house just after midnight; weather keeps getting more fun as we go, but this whole cycle has got to be giving the avy/snow safety pros some serious heartburn right now.
Really, it's still been a decent rule of thumb. It hasn't been a very good ski season until a couple of weeks ago and when it all comes at once like this, it's less optimal for ski touring.
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