Persistent low pressure to fill Northwest with gloom

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Think spring sunshine has finally taken hold in the Northwest? Think again. A deep, cold and unseasonably potent low-pressure system is forecast to drop south and east from northern British Columbia and position itself off the coast of northwestern Washington this week.

Because of a blocking pattern in the atmosphere downstream to the east of our region, this low will likely sit and spin spokes of moisture circulating counterclockwise around its center into the state for several days. This will begin late Tuesday and will possibly extend well into the upcoming Memorial Day weekend.

This low will bring a variety of weather with it — very little of which will either be appropriate for the time of year or even remotely welcome on the traditional inaugural weekend of the summer season.

In the Cascades, snow levels may fall as low as 3,000-4,000 feet initially before rising slowly as the week progresses. For northern and northeastern Washington, periods of heavy rain may lead to rises on some of the major rivers in that area while occasional thunderstorms may rumble over southeastern parts of the state and northeastern Oregon.

Locally, there will be a reasonable chance of showers every day through Saturday, and perhaps beyond, along with afternoon highs that will struggle mightily to reach the 60-degree mark on Wednesday and Thursday (about 12-14 degrees below normal for the third week of May) before regaining some ground over the weekend.

Overnight lows early Thursday could dip into the 30s in some locations, depending upon the amount of residual cloudiness and wind that night, so shorts will likely be exchanged for sweat pants over the next few days.

Rainfall will generally be light for the Walla Walla Valley — about a quarter of an inch or so — with higher amounts possible in the nearby Blues.

This meteorological news is distressing from several standpoints. In the vineyard, some vines are approaching bloom time, during which the grape’s tiny flowers are subject to any number of poor outcomes owing to untimely moisture and cold. Their pollination can be seriously reduced by both of these factors.

Poor flower pollination will result in fewer berries and lighter yields at the end of the year. In addition, moisture can combine with fungi that are fond of infecting dead or dying flower parts, leading to an increased chance of bunch rot later, as grapes begin to accumulate sugar in August and September.

Recreationally, only the most mean-spirited and curmudgeonly of people would wish to see the upcoming holiday weekend marred by rain and cold, though your weatherperson had a chance to practice for just such inhospitable weather this past weekend during a brief jaunt to a very windy and slightly damp Fishhook Park on the Snake River. The occasion was the maiden voyage of his girlfriend’s new camper trailer, accompanied by her two dogs.

He learned a few very valuable lessons on this shakedown cruise:

  1. The square footage of a camper is inversely proportional to how hard it is raining or how windy it is outside.
  2. No matter who is sleeping where, and irrespective of the bed size, both dogs will wish to sleep in the same bed and will go to any length to make sure they are accommodated there.
  3. Never put your face near the “black water” drain to check on the progress of emptying that tank.
  4. If you hit your head on a cabinet, doorway or any piece of equipment attached to the trailer, you will invariably hit yourself in the exact same spot again and again, and will end the weekend with an ugly, bloody bruise to show for your trouble.

With the prospect of a second trip looming large for this weekend, it is not at all difficult to understand why your forecaster might wish to maximize his “out-of-trailer” time. If the western Idaho weather does not cooperate to this end, there is a good chance that next Monday will find him girlfriendless, head bandaged, covered from head to toe in dog hair and hitching a ride back to Walla Walla.

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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