December 25, 2013

When Will the Western Snow Drought End?

There is no skiing at Snoqualmie Summit.

The Hoodoo, Willamette Pass, and Mt. Ashland ski areas in Oregon are not yet open.

 The WSDOT cams at Denny Creek and Hyak, on the west and east sides of Snoqualme Pass, tell the sparse-snow story well.

Looking at a map of snow-water-equivalent (or SWE), the amount of water in the current snow pack, tells the story.  The Washington Cascades have about 50% of normal, while in Oregon the snow pack is about 25% of normal.   The snow in the Sierra Nevada is no better, running about one-third of normal.
 For those enjoying alpine and nordic skiing, sledding, or snow fun in the mountains this is not a good year.  And let me be frank up front:  meteorologists did not expect this situation.  This is neutral year (neither El Nino or La Nina) and we had no reason to expect snow-drought conditions.

The reason for the lack of snow is clear:  a lack of precipitation associated with a highly persistent ridge over the eastern Pacific (see my previous blog on this). Here is the percentage of normal precipitation for the past 60 days. Lots of California and parts of the NW have received LESS THAN 25% of normal.  A number of climatological stations in California will have their driest year on record in 2013.   Those are major records to break.
Another way to look at this drought is to find exactly how much precipitation we have missed.  How many inches of precipitation below normal? (see graphic)  Most of northern CA through western Oregon/Washington are down 8 inches or more, with some twice that.
 So the question you all have is naturally is this:  will this snow/precipitation drought end soon?

And my answer is a depressing one:  very little is going to change for the next week or so. Here is the precipitation predicted by the UW WRF model for the next 72 h. Dry in Oregon and California and just some light precipitation over northwest Washington State.

The next 72 hours, which gets us to the end of the year?  Same thing.  Other models (e.g., the European Center, UKMET office) are consistent with this picture. Persistent ridging over the eastern Pacific is pushing weather systems into British Columbia and southeast Alaska.  Perhaps Baker will get a bit of freshening and Whistler even more.

The National Weather Service also runs their models out several months as part of the Climate Forecasting System.  Here is the predicted difference of precipitation from normal (called an anomaly) for January through February.  Pretty much the same story as described above--very dry in California, dry in Oregon and a mixed bag in Washington, while BC is wetter than normal.
Of course, the skill of the monthly forecasts is far less than the one-week predictions, but at this point the long-range view is not favorable for NW snow accumulation in the mountains.  The implications in California are very serious if these forecasts are correct.   The only bright spot for CA is that the snow pack is decent now in Colorado, eastern Nevada, and in Utah, so hopefully the Colorado River flows, which are an important water supply for parts of CA, will be near normal.

Praying for Snow

Fracking and Ozone

UW Professor Becky Alexander has established a page on the Microoryza crowdfunding web site that outlines her project  to understand why natural gas fracking often leads to high ozone values over snow (go here to see it). If you want to learn more about this important project and how you can help it happen, check out the web site.


  1. Sadly Western Washington has been more fortunate with grazing storms. It slowly gets worse as you head south. What Seattle will end little below average for the year? Portland is well below average, Medford etc.

    I was bored grazing through NWS yearly charts the other day. Get this, San Francisco averages 20 inches. This year they have received 3.38. Insane.

  2. Weren't we stuck under a ridge last winter as well?

  3. Another boring winter. Don't worry, I'm sure a stubborn trough will show up just in time for spring...

  4. @Hindu: IIRC on the last season we had a ridge during January/February but November/December systems had already built enough snow base on the Mountains, so even Snoqualmie was open.

    Cliff, we like to look at records :-) perhaps are we establishing a new record for late opening day for the Summit at Snoqualmie? I can't find that date on the internet...

  5. Cliff

    Looks like the models were a bit off for the NW corner of the state. We are getting some significant rain in the SJIs today...and loving it!


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