Thursday, September 11, 2014

First Polar Outbreak Portends Ominous Winter

The northeast wind blew ferociously all night last night. You may not have noticed, but we here in Eastern Washington are in the midst of a Polar Outbreak - a weather pattern that reeks havoc with wine grapes in the winter. You didn't notice? That's because the temperatures up north where the cold air comes from are still moderately warm.
Here is what happens. The jet stream makes a big loop up the Pacific Ocean into Alaska, then turns south into Alberta, Canada, the southwest into eastern Washington.
Normally, this big loop misses us and hits Montana, but yesterday and today it is looping further west and hitting us.
Why does this portend a nasty winter? First there is an El Niño developing in the Pacific - good news for California, but bad news for Washington. (Oddly there is a point in southern Oregon that is not affected either way during El Niño/ La Niña.) The jet stream has a wet and dry side. El Niño puts California on the wet side and Washington on the dry side. It is also the time that Polar Outbreaks are most likely to happen and happen strongly. Usually we get two or three of these per winter. This is the earliest I can remember. Because we are on the dry side of the jet stream, next year could be a short water year in the Yakima Basin.
Another serious problem with a Polar Outbreak is that they are often preceded by the Pineapple Express, a strong jet stream directly from Hawaii. This causes the grapes to lose their cold hardiness. Like a giant snake, the jet stream then loops northward in a matter of hours.
The forecast for tonight is 37o. The normal low is 45o and the record low is 35o. If this were winter it would be serious.
What to watch for: if the temperature in Fairbanks, Alaska reaches 40o below this winter, expect a serious Arctic Outbreak.

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