Tuesday, February 25, 2014

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Two Waves: Plenty of Powder

Winter returns after some sunny and warm conditions over the past week and a half. Two separate storms will impact the Sierra Wednesday and into the weekend. These storms will be a colder overall but also drier than the previous two big storms that we've had in the past month.

The first storm will come through Wednesday afternoon through Thursday evening. That storm will bring us about 10-18" of new snow. The snow level will begin around 7500' and drop to around 6000'. The next storm is right on its heels and begins early Friday morning. This will bring another 16-24"of powder to the Sierra. So by Saturday night we are expecting a solid 2-3' of snow with the highest elevations totaling over 3' and could hit 3.5'. 

NOAA HPC precipitation totals through Saturday evening. 2-4" of liquid precipitation is expected across the Sierra

The overall atmospheric pattern is somewhat similar to our previous storms since the last week of January although we don't have as good of a moisture connection (no atmospheric river). We have cold air pushing south and west from Canada and a large trough off the Pacific coast. The ridge over us thins out and breaks down. Almost the entire U.S. is in a troughing pattern by late this week due to this.

Precipitable water associated with first storm. The moisture with this storm is not as good as the last big one.

The first storm is a smaller shortwave that moves away from the larger trough in the Pacific. The main jet will pass just south of Tahoe but we will benefit from being on the cold side of the jet and having adequate dynamics to aid the snowmaking process. The second storm is a little stronger and colder but passes further to our south. The colder temps and not quite perpendicular (and lighter, more southerly) flow will help ease the rain shadow a bit meaning more snowfall east of the crest than the last storm.

Both images show mid-level temperatures, heights, and winds. Top image shows the first storm, the smaller shortwave and shows the general troughing over the U.S. The bottom image shows the larger trough moving across the West Coast late this week.

The weekend has us in northwest flow, which could provide some light on and off snow, but the moisture connection is pretty weak as of now. The strongest winds will be to our south, but it will still be breezy during the storms.

So we should have some choice powder to ski by Saturday morning and really Thursday through the weekend. So go forth and shred!


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