December waves wan over weather

Advertisement

No travel agent in his or her right mind would choose photos taken in late November for use in a brochure to extol the virtues of southeastern Washington and entice would-be visitors to this part of the world.

Picture if you will images of frosty, gray mornings against a virtually colorless backdrop of trees and vines stripped bare by wind and rain in the muted half-light of days that seem to end in creeping darkness before the afternoon has barely begun. Not a particularly successful recipe for the seduction of travelers seeking a warm and welcoming destination.

December, however, although subject to the same meteorological and astronomical influences as its wan predecessor, benefits enormously from its intimate association with holidays — a plethora of festive lights, food and music that effectively negate its true position as the darkest month of the year.

Our recent overall weather pattern has done little to change our usual perspective of the charms offered by late fall here in the Walla Walla Valley. Last week’s freezing fog did eventually yield to the relentless push of a mild and moisture-laden southwesterly flow stretching well out into the Pacific near Hawaii.

In northern California this so-called “Pineapple Connection” was responsible for fallen trees, flooding and landslides over four days of downpours that dumped in excess of 10 inches of rain.

This long fetch of moisture bulled its way northeastward into Washington, where the state’s mountainous spine wrung out considerable rainfall on the west side of the Cascades as the moisture stream was forced to rise, cool and condense.

Snow levels were high in the relatively warm maritime air that made it’s way east to the Walla Walla Valley. This warmth was reflected locally in weekend highs that topped the 60-degree mark — nearly 20 degrees above normal for this time of year.

Cold air has been bottled up in western Canada by the strong southwesterly jet. Until that changes, higher than normal temperatures will be the rule rather than the exception in southeastern Washington.

The medium range forecasts do not currently appear to offer much hope for anything in the way of natural flocking for our local evergreens anytime soon.

A warm front predicted to cross our area late Monday will lead to a good chance for some rain by early today, after which the passage of the associated cold front will lower both afternoon readings and snow levels in the Blue Mountains. But the cooler air will be too slow to filter in to allow for much accumulation there.

The resulting northwesterly flow will permit a weak wave or two to glide over the area, with one on Friday possibly touching off a few very light showers on the Valley floor along with light snow in the mountains.

By the coming weekend, the forecasting models begin to bicker again like an old married couple. Both the Global Forecast System and the European Center for Mid-Range Weather Forecasting indicate a trough of low pressure for Saturday and Sunday, with a cool and generally dry northwesterly flow in place with just a few upslope showers in the vicinity of the Blues.

The difference between the two is that the GFS is a tad deeper with the trough with snow elevations as low as 1,000 feet compared to the ECMWF, which is advertising snow levels closer to 2,000 feet with a somewhat shallower trough.

From a viticultural point of view, a good cold air intrusion would be of benefit to our vines in order to build up their tolerance to potential deep cold injury. Grape vine acclimation to cold is a dynamic process and is quite responsive to ups and downs of ambient air temperature so that a protracted spell of mild weather can actually lessen their tolerance to an incipient cold event. The 16-day outlook, however, indicates very little chance of any truly cold weather here through mid-month.

Though your forecaster spent hundreds recently in a fruitless attempt at the huge Powerball jackpot (always a smart investment), he has just enough left over to put a ten-spot on a few snow flurries this weekend in town to help everyone get in a more seasonally appropriate mood.

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 jeffrey.popick@wwcc.edu.

Comments

Use the comment form below to begin a discussion about this content.

Sign in to comment

Click here to sign in