THE WEATHERVINE - Wicked hail dings vines in June storm

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As if on cue to prove a point made here recently, two Saturdays ago Walla Walla's notoriously changeable weather provided a wildly unforgettable display. Pulling a stunning - but fortunately short-lived surprise - a hailstorm arose out of a perfectly sunny sky and unleashed its wrath with all the elements of a B-grade horror movie, or perhaps something out of the "Wizard of Oz."

A clear, mild morning gave way to a pleasantly warm afternoon with nary a hint of what was to come until darkening clouds reared up from the southwest shortly after 1 p.m. I gave the gathering darkness little thought until it became evident that these clouds were becoming more ominous with each passing minute and were making obvious and rapid progress toward our fair city.

Forty-five minutes later it had become abundantly clear something quite unusual was afoot and that this was not going to the garden-variety thundershower that occasionally visits our area during the warmer months.

A rumble of thunder announced its imminent arrival - as did the appearance of a jet-black, flat-bottomed cloud, known meteorologically as a "shelf cloud" and a signature of a severe thunderstorms of occasionally epic proportions. This kind of cloud forms as a cold-air downburst pushed earthward by heavy rain falling from the cell spreads out in front of the advancing storm and lifts warm, moist air ahead of it high enough to get it to condense and assume the "shelf" shape.

A sweeping rush of cold air - the temperature actually plummeted in town from 77 degrees to 57 in less than 20 minutes! - preceded the onset of a driving rain quickly augmented by dime-size hail clattering crazily off any hard surface it struck. With the malevolent cloud now hovering directly overhead and the sharp sting of wind-propelled hailstones, people who were outdoors observing the compelling view ran for cover as if a swarm of nasty outer-space creatures had been loosed from the blackness.

Your weatherperson was, of course, mesmerized by the entire scenario and lingered until it became certain that to remain outdoors could prove to be hazardous to one's health. The only thing missing at this point were Uncle Henry and Auntie Em shouting vainly into the teeth of the fierce wind for the peregrinating Dorothy and her beloved Toto.

The source of this mayhem was a stubborn low pressure system spinning just off the Oregon coast. Its counterclockwise circulation pumped copious amounts of Pacific moisture into the Evergreen State on a brisk southerly wind.

This moisture, along with some robust daytime heating and a bit of lift furnished by a weak vortex of low pressure above, spun off from the main coastal low and combined to provide the necessary ingredients to destabilize the atmosphere and touch off the tumult.

Hail, of course, is no laughing matter - particularly where agriculture is concerned. After snapping a few frantic photos of the hailstones nestled on my front lawn, thoughts turned anxiously to my vines at Walla Walla Community College's teaching vineyard.

The scene there was better than my worst imaginings but bore powerful testimony to the ferocity of the storm: punctured and shredded leaves, broken shoot tips and the occasional grape cluster wrenched from the vine and lying forlorn on the muddy ground.

Not a pretty picture, indeed, but a similar storm of longer duration would have exacted a much higher toll, such as when a recent 15-minute storm in the Champagne region of France became the third most costly hail event in its history.

If we are to believe the 16-day outlook from the National Weather Service's Climate Prediction Center, the next several days look considerably more benign and summerlike than last week, with no threat of rain. Fair skies and seasonable temperatures should be the rule, with very little chance of a rerun of the Hollywood-type drama that played here June 23.

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.

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