Blustery weekend nearly has grape growers in a jam

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What had been a near-textbook vintage so far this year, with the sort of weather and growing conditions Washington vintners usually can only dream about, has suddenly taken a rather nightmarish turn. A cool, wet and windy system lashed a broad area of the Pacific Northwest this weekend, dashing hopes of an early end to the 2013 season.

An unseasonably powerful early-season Pacific storm fueled by the remnants of former west Pacific Typhoon Pabuk, which grazed Japan last week with wind and rain, and driven by a west-to-east jet screaming overhead at 170 knots slammed ashore with copious amounts of precipitation and winds gusting over hurricane force.

As usual, the windward side of the Cascades felt the brunt of the storm. Ten inches or more of rainfall was not uncommon there, along with winds in excess of 80 miles per hour, as some of the jet stream energy aloft was mixed down to the surface by sinking cold air associated with the system.

All of Washington’s viticultural areas were affected by the inclement weather, though the Walla Walla Valley — because of the rain-shadowing effects of the Cascades and Blues — received just a modest half-inch through Monday morning. That rainfall was exacerbated by winds that gusted to 49 miles per hour on Saturday night and 41 mph late Sunday, unfortunately helping that water to get deep into ripening grape clusters, where fungal infections are most likely to occur.

Grapes that were nearing sufficient maturity to be harvested may have been set back a bit by the cool, wet weather. Picking may be delayed while vintners wait for the sun to return and dry things out, and for just enough bump in the sugars to ensure that the fruit meets minimum ripeness requirements. As we move into October, that becomes an increasingly tall order as day length decreases markedly and daily maximum temperatures fall into the 60s. What is now needed is a protracted period of sunny, warm weather to get the vintage back on track. That does not appear likely until the latter portion of the week, as a troughy pattern is forecast to linger over the area through Wednesday with chances of showers each day.

By Thursday, high pressure will build back over Eastern Washington for a fairer and milder regime, before another front approaches the Pacific Northwest for the weekend with an increasing possibility of showers here by Sunday.

The bright side of all this is the calendar, which indicates that October has only just begun and that there is ample time — if the weather cooperates — to right the ship and end up with a very good year for our local grapes and wine. Pity the poor folks engaged in our business in places like the Willamette Valley or the Puget Sound, where 3-5 inches of rain fell this weekend — enough rain to cause a major dilution of sugars and flavors and practically guaranteeing some degree of rot in their fruit.

The National Weather Service appears to have seriously underperformed with this most recent event, both in the short and long term. The 30- and 90-day suite of outlooks from the Climate Prediction Center has, since the early summer, touted the likeliness of a drier-than-normal early fall, while the shorter-term models failed to pick up on the influence of the tropical storm last week until just three days before its arrival. This proved once again (as if further proof were needed) that meteorology is still the most inexact of sciences.

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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