Saturday, December 14, 2019

Good News for Northwest Snow

I have gotten a number of emails from folks wondering about snow, including their worries about snow recreation over the holidays.   So let's talk snow.

First, we need some perspective.   Here is the snow depth analysis for 2019 on December 14th (today) compared to the snow distribution on Dec. 14th of the past two years.    Superficially, they look similar, but there are differences.  Considerably more snow in the Cascades last year, but there is more snow this year over southeastern Oregon.


 Another approach is to look at the latest SNOTEL observations, this time viewing the percent of normal snow water equivalent (amount of water in the snow).  Yes, much of southeastern Oregon has more snow than normal, as does California and Nevada.  The western slopes of the Cascades and Olympics are around 35% of normal, with generally more snow over eastern WA (roughly 55% of normal).
So Washington is low, but not crazy low (like 2015). A few big snow events can bring these early season numbers up very quickly (since the snowpack is less in December than in, say, March).

So what about the critical 10 days ahead of us?  I have an optimistic forecast for snow lovers.

The next four days will not brings substantial regional snow, except for some snow showers on the western side of the central WA Cascades due to a convergence zone.  To illustrate, here is the total snowfall between 4 PM Friday and 4 PM Sunday from the European Center model: 6-12 inches over favored areas--good for Stevens to Snoqualmie, but probably not enough to allow them to open.


But after a dry period through Tuesday,  a series of weather system will move in, generally just to the south of us.  That is good for snow, since we will stay relatively cool. 

Consider the total snowfall through 4 PM Friday.   Now we are talking:  1-2 feet above 3500 ft.


Readers of this blog are trained to know that one should not look at a single forecast.  We have to look at many forecasts (an ensemble) to judge our confidence in a prediction.  So now let's look at the ensemble snow forecast from the NOAA/NWS system (GEFS) for Stampede Pass (roughly 4000 ft elevation in the central WA Cascades). 

 I will show you my favorite rendition of an ensemble forecast--a plume diagram (each line is a different forecast).  Wow! Time to check your bindings!   Nearly every prediction in going for substantial snow, with the average (black line) heading towards 18 inches!  Even more exciting, the high resolution forecast (blue line), which is capable of getting the mountain enhancement better, is running towards 30 inches by December 22nd.

The bottom line of all this.   There is a high probability that the weather gods will deliver substantial snow to our region before the holidays.  Enough to open virtually all the ski areas (of course Snoqualme Summit being lowest, will have the least).  Our snowpack numbers will end up close to normal by the end of the month.  Life is good.




13 comments:

  1. I hope this is true, but just a few days ago a whole lot of snow was forecast for Thursday-Friday and it didn't happen.

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    1. We had signifcant snow in north central WA near the crest. A few more inches will make things perfect but the xc skiing today was quite acceptable.

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    2. The last storm system did not pan out in terms of opening Stevens or Summit last weekend. They didn't get as much snow as forecast, so they backed it off another week. Both are counting on this week's predicted snowfall for next weekend's opening. It was 30 degrees and raining lightly when I crossed Snoqualmie Pass yesterday afternoon.

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  2. Wish I lived near Mt. Baker, that place seems to get more snow than almost anywhere else in the country, pehaps even more than the Northern Rockies.

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    1. MT Baker holds the world record for annual snow fall, beating out Paradise at Mt Rainier

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    2. Snowiest place in the country is definitely in southern AK.

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  3. Hello Dr. Mass,

    Any impact to the lowlands ?

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  4. Cliff,

    I do enjoy a winter wonderland! This is good news.

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  5. Cliff,

    Speaking of snow and a winter wonderland . . . https://www.youtube.com/watch?v=yMTd1X9c6kg

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  6. Minimum overnight temp in NW Bellingham was 31.4F

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  7. Yes, what about the lowlands? I see where they put snow into the forecast and then they take it out.

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