High pressure storm deflects storms, preserves splendid fall

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Thanks to a sprawling area of high pressure whose center resides just off the coast of Washington and Oregon, the Walla Walla Valley has enjoyed some of the finest fall weather to be found anywhere in the United States over the last couple of weeks.

Under such a pattern, incoming Pacific storms are shunted up and over the high into Canada. From there they plunge southward into the central and eastern U.S., bringing cool and inclement weather to those parts of the country while the vast majority of the West Coast remains high and dry.

With the generally clear skies, ample sunshine and subsiding dry air associated with a region of high pressure, afternoon temperatures have risen into the rather balmy mid- and upper 60s. Nighttime lows have still been on the chilly side as such a regime promotes maximum reradiation of the day’s accumulated heat. With the calm or very light winds, cold air has continued to pool overnight in the lower elevations locally, often leading to great disparities in early-morning readings over relatively short distances. On several recent mornings this difference has ranged up to an astounding 15-18 degrees between the airport and less lofty locations to the west of Walla Walla near Touchet.

Subfreezing overnight lows last week brought a sudden end to this year’s grape harvest for many. Several wineries were obliged to scramble to bring grapes in as quickly as possible after leaves and fruit had been subjected to the rigors of minima dipping down into the mid-and upper 20s in many spots.

Your weatherperson’s vineyards near and at Walla Walla Community College enjoy a distinct advantage in this regard, as their 1,200-foot elevation almost always allows for the drainage of cold air away from the various sites downhill to the west and south. He gladly passes the burden of subfreezing air in both the spring and fall down the line to some of his less-fortunate neighbors, whose plight he feels keenly every time the unmistakable roar of wind machines resonates across the Valley in the still night air.

The fine weather has allowed those grape growers as yet untouched by fall frost to take their time in bringing in the last of their fruit. This will undoubtedly be a very busy week in the Valley for harvesting grapes as the calendar advances relentlessly toward the new month. There are few engaged in viticulture here who wish to tempt the fates by allowing grapes to hang into November, for such a stretch of perfect weather as we have recently been enjoying must certainly come to an end soon, as noted by the introspective Beatle George Harrison many years ago. Yes, all things must pass, and this week’s sunny, warm and dry weather will too — but not for several more days.

Though the Global Forecast System’s 16-day outlook long ago removed the threat of a rapid transition to a very cold and wet pattern mentioned here last week, it still adheres to the notion that cooler and wetter weather will eventually make its way back into the forecast during the first week of the upcoming month, as the seemingly indomitable high breaks down and begins to permit storm systems to enter the Pacific Northwest.

In the meantime, we may enjoy the many delights offered by the current exceptional regime: sunny, mild and dry weather that lends itself to an extraordinarily wide variety of outdoor activities, including walking the dogs on the newly reopened Bennington Lake trails. Your observant forecaster noticed many shameless scofflaws flouting the recent closure while exercising his own canine companions out there during the government shutdown. What kind of example were these lawbreakers setting for the rest of us?

Our last precipitation here occurred on October 12 (a meager one-hundredth of an inch of rain), and should this xeric trend continue through the end of the month — which now appears quite possible — October will go down as the driest in 25 years, and one of the driest since 1949, when weather records begun to be kept here. The monthly normal for October is 1.68”, and we now stand at a scant two-tenths of an inch — a number which greatly pleases viticulturists who just a few weeks ago were despondent over the gray skies and intermittent rainfall that plagued the harvest during the latter part of September.

A lifelong fan of both the weather and the Baltimore Orioles, Jeff Popick is an instructor at the Center for Enology and Viticulture at Walla Walla Community College and manages the school’s teaching vineyard. Send your questions and comments to him at jeffrey.popick@wwcc.edu.

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