Grapevines love heat, should adore next few weeks

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As if your weatherperson didn’t have enough on his hands with the IRS, it seems as if the NSA has been monitoring his phone conversations for some time now in order to determine how he could be so uncannily accurate week after week with his weather forecasts.

They can listen all they want but they’ll never lay their hands on the magic crystal ball or the mystical I Ching sticks that provide him such clear insight into the often inscrutable world of meteorology. Have these people no shame?

A sultry Walla Walla weekend was the result of a pesky area of low pressure just off the Oregon coast, whose counterclockwise circulation brought a strong southerly flow to the area, importing both heat and moisture into the Valley. Sunday’s high temperature of 94 felt even more uncomfortable thanks to the increased humidity, and your heavy and heavily perspiring forecaster was reminded of his childhood days in steamy Baltimore, Md., where summertime survival is an art that demands savvy, stamina and frequent showers, as well as large quantities of the local suds known as National beer.

Though considerable cloudiness developed later in the day, no precipitation could be squeezed from those clouds, owing to the large distance separating the center of the low from southeastern Washington. However, as the system began to plod eastward on Monday, the small disturbances rotating around its center inched closer and closer to Walla Walla. The added moisture, combined with daytime heating, encouraged the formation of buildups that threatened to bring showers on Monday afternoon and evening.

An even better chance of precipitation is seen for this afternoon and evening as the center of low pressure makes its way slowly across the state. There is even an outside chance at some stratiform (steadier) rain overnight into early Wednesday with the passage of the system as it heads off into northeastern Washington and the Idaho panhandle. Rainfall amounts may total a quarter-inch or more where thunderstorms occur. High temperatures will come down considerably as a result of the increased cloud cover and a good push of maritime air associated with the low.

By the end of the week, the system will have progressed into Montana. Westerly winds in its wake should lead to a gradual warming and drying trend that will cause afternoon maxima to rebound into the 80s by Saturday and Sunday under mostly clear skies. However, one of the models — the European Center for Mid-range Weather Forecasting — is indicating a cold front moving in from the west on Monday that could bring another round of light precipitation to our region.

Earlier runs of the 16-day Global Forecast model had been indicating more inclement weather around the 25th or 26th of the month, but the latest version of this forecast has removed this rain in favor of some significantly warmer temperatures that may peak around the Fourth of July holiday, with highs possibly reaching well into the 90s, for the first real heat wave of the summer season.

In the vineyard, our heat-loving grapevines are soaking up the mid-June warmth like vacationers on a beach excursion. Leaf canopies continue to grow with regular applications of water, and the newly formed berries — products of a very successful bloom — will be growing exponentially under the extremely favorable conditions.

Leaf-pulling will begin shortly. This is a canopy management operation that is designed to expose the clusters to sunlight and open the canopy for better air and light penetration. All of these will improve fruit quality, lessen the possibility of mildew and molds and help ensure an adequate crop for next season, as the vines’ fruitfulness for the next year is largely determined in the previous summer. Of course, this leaf removal must be performed judiciously so as not to deprive the vine of too much leaf area — thus limiting its ability to produce the carbohydrates it needs to sustain its growth — or allow the fruit to be sunburned by overexposure to the hot summer sun.

Take a stroll into your nearest vineyard and admire nature’s (and the vineyard manager’s) handiwork one of these days!

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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