July featured a battle of competing weather systems that was accurately reflected by a neatly drawn dichotomy in the average temperatures between eastern and western portions of Washington state.
A fairly persistent trough of low pressure that hung near the coast for much of the month led to readings that were 1 to 1.5 degrees below normal as the westerly flow around that trough brought a decent marine push to the west side of the Cascades.
The eastern part of the state, on the other hand, was largely under the influence of a sprawling area of high pressure over the Rocky Mountains and western Plains that was partly responsible for creating the hottest July recorded in the United States since 1895 — the first year of tracking such data. Average temperatures east of the Cascades were between 1 and 3.5 degrees above normal.
In the Walla Walla Valley, a week or so of downright hot weather at the beginning of the month was caused by an expansion of the high pressure system, and its clockwise flow pushed large quantities of very warm air from the desert Southwest northward into our area.
For the month, our highs were about a half degree above normal, a figure tempered somewhat by several days of mostly cloudy weather during July’s third week.
Forecast models are now coming into better agreement concerning the next phase of this meteorological battle between high and low pressures.
Although it is perhaps not quite of the magnitude as more far-reaching battles like good versus evil or right versus wrong — nor quite as amusing (in a pathetically comical sort of way) as the grade-school level media battle the two candidates for President are currently waging — its outcome may have a more immediate and palpable effect on our day-to-day lives.
For some time now, the ECMWF (aka European) forecast model has been showing a rather significant pattern change for mid-month involving markedly cooler temperatures and increasing chances of measurable precipitation. The Global Forecast System model, however, was almost as adamant in maintaining a continuation of our warm and dry regime.
In such a case, which is not at all unusual, forecasters are fond of hedging their bets until “the models come into better agreement.”
The two models have indeed achieved a sort of détente with the GFS now leaning more toward the ECMWF scenario, in which the low trough will deepen and enlarge over the Pacific Northwest and push the high pressure system south and east. That indicates a change to cooler and possibly damper weather later this week.
In fact, if the GFS is correct, much of the second half of August will see somewhat cooler than normal temperatures with occasional chances for rainfall as discrete waves of low pressure make their way periodically through the trough.
Grape growers, whose fruit is heading into the sugar accumulating stage called “veraison,” will follow this pattern change with great interest. That’s because wet weather at anytime from here to harvest could spell possible trouble with a fungus called botrytis, which can easily turn ripening bunches of grapes to mush under the right conditions.
Your humble weather forecaster, fresh from a jaunt to Lake Tahoe where the gambling gods allowed him to escape on the plus side of the ledger, is feeling hot — like his beloved Baltimore baseball team. So he will toss his well-worn and very lucky Oriole hat into the ring with the ECMWF forecasters and bet hard on the parlay featuring a shift to the cooler and wetter side.
With the winnings, he will throw caution to this week’s freshening westerly wind and go all in on an Oriole World Series victory, despite current odds of 50-1. And come the end of October, he will retire to the Florida Keys for a life of fishing interrupted only by long stretches of pure indolence and an occasional highly entertaining round of poorly played golf.
So, you see, the much-anticipated outcome of this week’s clash of the high- and low-pressure weather titans will most certainly have a profound effect on at least one person’s life.
A lifelong fan of both the weather and the Baltimore Orioles, Jeff Popick is an instructor at the Enology and Viticulture Center at Walla Walla Community College and manages the school’s teaching vineyard. Send your questions and comments to him at firstname.lastname@example.org.