Your peripatetic prognosticator returned to Walla Walla on Friday after a 24-hour whirlwind tour of Las Vegas, where the heat was definitely on.
Stepping off the plane in Pasco, the 99-degree afternoon temperature there seemed positively refreshing after enduring the previous day’s 110-degree parboiling in Sin City. There, an influx of monsoonal moisture provided just enough relative humidity to thoroughly steam to a bright lobster-like red those of us unfortunates who happened to be visiting America’s most notorious city last Thursday.
Not even a steady intake of overpriced margaritas and beers was sufficient to provide relief that same evening from a midnight reading of 95 breathtaking, energy-sapping degrees. Never was anyone so glad to step aboard his bare-bones Allegiant jet (two dollars for water and no reclining seats!) the following day for a trip back to the somewhat cooler and considerably drier Walla Walla Valley.
An extended string of much-above-normal days finally came to an end Saturday with a long-awaited influx of maritime air courtesy of a weak trough passing to our north along the Canadian border. Afternoon highs dipped down into territory that had not recently been explored on our local thermometers — upper 80s — which was actually a degree or two below the norms for the date.
Climatologically, we are currently in what is considered the hottest week of the year, with daytime highs averaging 91-92 degrees. The week will start out very close to that before a gradual increase in both moisture and cloudiness slices 2 to 5 degrees off those highs as we move toward week’s end. These will come to us by way of an area of low pressure that is forecast to install itself just off the coast and begin to pump Pacific moisture on the southerly and southwesterly flow that will set up around the center of circulation.
This low will move about as torpidly as your overstuffed forecaster emerging from the buffet at the Aria last Thursday night where excessive amounts of food partner with gluttony in a Vegas-style pairing designed to cater to the most ravenous among us. Your weatherperson felt very much like a snake that swallows a rabbit and is virtually incapable of any movement afterward, as the too-large meal slowly works its way through its system.
As the low crawls toward the coast today, increasing amounts of moisture will initially begin to spread over southern Oregon. On Wednesday this will reach Southeast Washington, where it will combine with daytime heating to produce scattered showers and thunderstorms. This activity will increase in coverage and intensity on Thursday as the low approaches our area. Dynamics of lift will increase due to the proximity of the rising air associated with the low and augmented by the lift provided by a weak cold front attached to the low, which will undercut the warm air out ahead and aid in the convective (thunderstorm-making) process.
The progress of this system across the state may be so snaillike that a chance of showers could linger in far eastern Washington into Saturday before it all moves out of the area, leaving a drier and warmer regime in its place for Sunday and the first part of next week. The 16-day Global Forecast System outlook is hinting at a possible return of convective activity for the weekend of August 10-11, but much could change before then.
What is certainly changing, however, is the color of some of our local grapes. The early ripeners have moved into the so-called period of veraison, in which softening, color change and sugar uptake signal the entrance into the viticultural homestretch that leads up to harvest. The abundance of heat this summer has accelerated the development of all grapes, and the accumulated number of growing-degree days, which was discussed in this space a few weeks ago, indicates that we are a good 10 days to two weeks ahead of average in our maturation process. This will help considerably in ensuring maximum ripeness for just about all the various wine grape varieties grown here in the Walla Walla AVA — something growers have not been able to say for several years.
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 firstname.lastname@example.org.