Summer continues, but Mother Nature drops hints of fall

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Summer 2013 rolls on with little change this week.

A westerly flow on Sunday and Monday brought drier air into the Walla Walla Valley, with occasional breezes to nearly 20 miles per hour that chased Friday and Saturday’s cloudiness and light showers off to the east. Friday night’s vivid lightning display was accompanied by a brief period of rain that deposited a meager four-hundredths of an inch in the airport rain gauge while providing great entertainment for many.

Your weatherperson parked himself in a chair in the back yard to admire Mother Nature’s atmospheric handiwork until the sudden arrival of big, fat raindrops forced him indoors. Otherwise, the remainder of the weekend was very similar to what we have seen this summer season: sunny skies with high temperatures in the low 90s.

However, for those who have been paying attention, subtle changes are occurring that presage a change of seasons in the not-too-distant future. Though the heat remains, the lowered sun angle compared to midsummer has taken a bit of the edge off its former fury. It is now a full 11 degrees lower in the sky at solar noon than it was back on July 1.

In addition, our day length is now decreasing by a good three minutes daily as we rush headlong toward the fall equinox just over a month from now on Sept. 22. We have lost one hour and 49 minutes of daylight since the first of July, and the noticeably earlier sunsets — along with a proliferation of meaningless preseason football games on TV — should serve as fair warning that summer 2013 will be singing its swan song sometime soon.

On a Sunday morning walk near Bennington Lake your forecaster could have sworn he felt the first stirrings of autumn on the very refreshing breeze that accompanied him and his canine companions. The surrounding tableau of golden wheat stubble against a flawless cerulean sky provided a decidedly fall-like setting for our perambulations, and on the way home, a single dried-up leaf falling from a tree seemed to announce that a change of seasons was indeed imminent — though the 90-degree high that afternoon made it somewhat more difficult to fully buy into that scenario.

In the vineyard, our local grapes are ripening rapidly in near-perfect conditions. The first of this fruit to be harvested will be earlier-maturing white varieties like sauvignon blanc and semillon, which — if all goes according to plan — will not be ready for picking until your weatherperson returns from a well-deserved vacation at the coast after Labor Day.

This week’s weather should not offer any impediment at all to the grapes’ continued ripening. A low pressure system off the central California coast will slowly move to the northeast and weaken as it does so. The modest amount of monsoon moisture it has entrained from the south will likely not make it farther north than central Oregon or the southern Blue Mountains by Wednesday afternoon, with a chance of showers and thundershowers. At this time, it seems unlikely that the Walla Walla Valley will see any activity from this system, though there is an outside shot at a stray shower, perhaps on Thursday, as it scoots by to our south and east. Temperatures this week will be a couple of degrees above normal as they continue to hover right around the 90-degree mark.

By the weekend, a deepening Gulf of Alaska trough will bring a cooler and moister regime to the area with a somewhat better chance of showers and afternoon readings falling back into the low to mid-80s by Monday under the influence of the trough. If you close your eyes and think of bright orange pumpkins, crunchy leaves underfoot and your favorite light sweater, it may almost seem like fall.

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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