The “Rain Shadow Effect”: A Good Climate Phenomenon for Walla Walla Valley Wines

by Miki The “This is the Life” Winer


Don’t you just love new wine terms? I sure do! Okay, so perhaps I’m a bit “wine geeky”, but if the shoe fits, wear it, right?


I first heard the term the “rain shadow effect” while attending the opening session of the 2018 Wine Bloggers Conference in Walla Walla, Washington. They had a panel of four women in the local wine industry that were introducing us to the Walla Walla Valley with regards to grape farming and one of them tossed out the term “rain shadow effect”. Of course to me, the ever-wondering “ooh, I have to know so let’s go ask Google” lady, I had to go find out. So here you go:



The “rain shadow effect” is very simply when an area of topographical elevation blocks the passage of rain clouds from one point to another. So let’s think about it from the Washington state perspective. You have warm moist air eastwardly coming off the Pacific Ocean only to be greeted by a big blockade of mountains called the Cascades. At that point, the air must rise and therefore encounters a cooler temperature which condenses the moisture into rain which falls on the mountains. As the air continues east, it does so devoid of moisture leaving the eastern side of Washington a technical desert only receiving 5-7 inches of rain a year.



Now, how is that minimal amount of rain actually good for growing grapes? It’s called “irrigation”. According to the very successful grape farmers in this area, it is much better to control the amount of water that grapes get instead of having moisture so abundant that the fruit is diluted by the volume and lose their flavor and acidity. So, although there is very little rainfall in eastern Washington, the vines are irrigated with groundwater, supplying just the right amount of water usually by a drizzling method so that the vines are provided just the right amount of water to survive but yet not enough so that they don’t have to struggle just a little bit. Remember, struggling vines make winner wines! Check out this video below which shows vineyard irrigation in action:

I hope you enjoyed this little wine education tidbit. And remember, until next time, it’s all about having fun with wine!



Miki “This is the Life” Winer

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