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Ice Storm Wasn’t Extreme; It Was Precise

December 23rd, 2016 by dk

I feel just a tiny bit responsible for our 2016 Ice Storm, since I dared winter — in print! — to show us something more than the “meh” weather we’d been tolerating in early December. To those who lost power for days or longer, had their roof or car punctured with the pointy sticks of nature, or slipped and fell on the ever-present ice, I’m sorry.

But to the weather itself, I say “Bravo!”

I’m not a fan of the cliché, but what we saw last week was very close to a perfect storm — perfect, as in precise. This storm was not the coldest, the deepest, the earliest, or the longest. The havoc it wreaked hit all sorts of extremes. The storm itself hit the magnificent middle, the hard-way half-way, the terrible ‘tween. This was a Goldilocks Storm.

Had it been one degree colder, we’d have gotten snow. One degree warmer, it would have been sleet. Either way, we wouldn’t still be talking about it. We wouldn’t have lost thousands of trees, and there wouldn’t be thousands of local residents now heading into their second week without power.

Everyone who could recharge their phones spent hours last week snapping photographs and posting them to Facebook. Glass tendrils extending tree branches or “dripping” from power lines regularly extended six inches. The ice casing over branches was routinely an inch thick.

Disney could not have designed a more compelling crystal city, but this one was real. The beauty was awesome, but think about the physics of it.

A drop of rain hits a power line. It moves laterally no more than a few inches. Then it begins to drip down an already formed icicle, aiming to wet the ground below. But before it reaches the end of the icy stalactite, it turns solid — adding length and weight to the emerging ice sculpture.

It all started with a not-uncommon weather inversion. Cold air lay on the valley floor with warm air above it. If the layers had been reversed, with the cold air above, it would have been hail. Without an inversion, it would have been snow (cold) or rain (warm) — either way, no big deal.

The precipitation fell exactly in the middle. The H2O started warm enough — but just barely — to fall as rain, then turned to ice after touching a cable or branch and before falling to the ground. That’s precise, or if you prefer, perfect. Gravity dueled with molecular cohesion, and gravity lost. (Water molecules are strongly cohesive because of their tetrahedral configuration, which is why liquids can extend above the brim of a glass without spilling over.)

Those icicles form best and longest when that liquid-to-liquid bonding occurs just long enough for the cold to turn it solid. That’s precision and it’s awesome. Colder, snow or hail; warmer, rain or sleet. But here we are. We can seek shelter, but trees are not so lucky.

The encasing ice adds enormous weight to each branch on each tree. Excepting the infirm, the ones that suffer most are those that extend outward from the trunk, parallel to the ground. I’m gonna say these frozen branches weigh up to ten times their normal weight. (I don’t know the exact physics here, so I used a round number and the word “gonna.”)

And then (no, we’re not done yet), the temperature stayed cold, and gravity staged its comeback. Mother Nature became a cruel yoga instructor: “… and HOLD (for five days). Feel the burn!” Those poor trees struggled mightily to keep their shape. You know you’ve lived in Oregon long enough when you start to see storms from the trees’ perspective.

Only one thing could have made this storm worse — some whipping wind to accompany the icy cold. If lateral force had been added, even more trees would have lost their branches or upended their roots. So, sorry, 2016, yours was not a “perfect storm,” but close.

Our temperate climate won’t hit the attention-grabbing extremes seen in other parts of the country. That’s no excuse not to be awed by nature’s power and precision. We’re wired to notice the extremes, but there’s another magnificence in clear view — smack dab in the middle.


Don Kahle ( writes a column each Friday for The Register-Guard and blogs at Kahle’s challenge to “meh” winter can be found here:

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