November 08, 2010

The Cascade Subsidence Zone

Suncadia Resort

There is a a nice (if somewhat tony) resort on the eastern side of the Cascades in Cle Elum called Suncadia (see picture above)--and the management really pushes the sun angle in their advertisements.

And a major new solar energy array is going to be installed during the next few years in our state: The Teanaway Solar Reserve, costing over 300 million dollars! Guess where it will be--right outside of Cle Elum.

So what is this all about? Why Cle Elum?

I believe the reason is that there is a band of territory on the eastern slopes of the Cascades that is one of the sunniest places in the with more than 300 days of sun a year.

You can get a hint of what is going on by looking at a few satellite is a sample.
If you look closely you will frequently see a roughly N-S band of clearing or less clouds east of the crest, and Cle Elum and vicinity gets a piece of it.

Why does this exist? The flow over the region is generally westerly...air coming from the west. Western Washington get the marine clouds and storms, and the clouds and precip are enhanced as they rise over the western slopes of the mountains. But east of the crest the air is descending strongly and that tends to cause the clouds to evaporate--giving you the clearing. The bowl..the lower areas of eastern W--are sunny enough in the summer, but tends to fill with fog and low clouds in the winter.

So if you want the most consistently sunny location you go for the eastern slopes, far enough away from the crest not to get any of the blow-over from the western side.

You guessed it--that location includes Cle Elum. Now there are surely other locations with similar benefits on the slopes to the north and south....but Cle Elum has certain I90.

But don't think sunny Cle Elum is paradise...they do have one issue. Wind, and lots of it. Suncadia during some periods might be called Windcadia....but that is only an attraction for meteorologists!


  1. Great post. It strikes me that there may be other even better spots that may not have as extensive climate data on the high ridges on the western portion of the Yakima Indian Reservation.

  2. Hey--long time reader first time writer--Have they considered building wind-farms in the Cle Elum area as well? What do you think it would take for that to happen?

  3. The Teanaway River area used to be a great place to camp & hike. Not too secluded any more though...Might as well put a solar array there :)

  4. Cliff,

    Normally I never disagree with you on your observations, but I've spent a long time in many areas in Kittitas County and these observations don't seem to match.

    The area where they're planning to put this array is in the Teanaway Valley. It's an amazingly picturesque location, but as evidenced by the sub-alpine biome that includes fairly dense pine trees – it is also a somewhat moist location. And as you know, typically moisture means clouds, and clouds make for a sub-optimal PV production location. The annual average rainfall of Cle Elum is 22.19 inches – which is still fairly wet. The descending, moisture laden air of that area also makes for fairly frequent thunder storms between Easton and Cle Elum.

    It doesn’t take much travel to go across a fairly dramatic change in vegetation (and precipitation) from the sub-alpine into the much drier shrub–steppe biome on the other side of Elk Heights, descending into Thorp. Just that move of some ~20 miles East yields a drop of rainfall by 2/3rds to an annual average of 8.89 inches in Ellensburg. Traveling further East, into the lower Yakima Valley (say the aptly named Sunnyside), you’re now in an area with a dramatically higher insolation than Cle Elum.

    I’m a big fan of solar power, and have 13 KW of array in Seattle myself, but planning to place a utility sized array in a comparatively cloudy area isn’t very smart – especially when it’s much sunnier just 20 miles to the East of their current site.

    -Steve A.

  5. Already an inch of snow in Ellensburg and still coming down! Just an FYI...

  6. Cliff ~ Accuweather is saying there is an "Arctic Cold Outbreak" beginning the third week of November. What's your take on that? Is La Nina FINALLY going to show up?

  7. Windlover...some advice. Accuweather has an uneven record out here...and in any case I would not get excited about forecasts weeks out!...cliff

  8. I grew up and currently live in this "subsidence zone" but west of Yakima. Just spent 2 years at CWU so I know this area well. You're correct about the climate and the sunny phenomenon, but Steve A is right.

    Every extra mile east of Cle Elum would make all the difference to a certain point.

    Cle Elum, mostly due to lower terrain W (Stampede Gap) is still to acceptable to moderate and strong westerly flow.

    The winter fog is true, but it can easily engulf the entire kittitas valley all the way up to Snoqualmie Pass. You might even get a few good summer days ruined due to usual convection that blooms just E of the crest too.

    It would be conveniently located to a major power grid (shown in your book) and located nicely for Seattlite engineers and investers. It is a good spot, but not the best.

  9. I generally cross the Cascades via Stevens Pass. Talking with some of the locals at Lake Wenatchee, I learned a saying, "Rain Free by Rayrock Springs" (Rayrock Springs is a knife shop along Hwy 2). And I have found that to be largely true... it's like the serious rain stops right about that area when you're heading east.

    Is the area around Lake Wenatchee another example of the subsidence zone? I know during many summertime afternoons the wind picks up out of the west late in the afternoon which makes me wonder... Thanks for the blog! Always informative!

  10. I also meant to ask - do you have any comments about the contrail left by that alleged missile fired off the California coast?

  11. Oh...I know Accuweather is not one is that far out! And I wasn't getting excited..just asking what your take on it was: i.e....what do your long range models say? I'm looking forward to a wild winter but so far it's been pretty mild...I was just wondering if you saw anything in the long range that might hint at La Nina finally visiting us! Thanks!

  12. windlover - kudos to AccuWeather for mentioning it, but they should just be saying it's a possibility to give people a heads-up, not really saying yet that it's going to happen. The medium- to long-term forecasts from the GFS (Global Forecast System, the US model) have been giving indications at arctic air moving in here toward late next week or the following weekend, and so has the European model to a lesser degree, but there is still quite a bit of variation and it's still awhile away in time. That said, three of the past four GFS runs over the last day have shown as such. I guess we'll see, and it's a possibility at this point - by no means anything to count on, however.

  13. Oh, oh, the S word has crept into a few long range forecasts. Before Thanksgiving???

  14. My research shows an average daily solar irradiance in Cle Elum of about 3.6kWh/m^2. That splits the difference between Seattle at 3.3 and Hanford at 4.1. The transmission line nearby, the clear cut land and the cold weather are benefits, along with job creation in a depressed area.


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