A ‘perfect’ storm?
Squall that struck Oregon in December was big, but maybe not the biggest on record
Tuesday, January 22, 2008 12:46 PM PST
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| In this photo released by Port Of Tillamook, a major storm hit the Northwest and damaged the Port of Tillamook Bay Railroad seen in this Dec. 6, 2007 photo in Oregon. The tracks run 95 miles through the Coast Range to Banks, to Port of Tillamook. |
ASTORIA (AP) — No doubt about it, December’s blast of coastal floods and windstorms was big. But how big?
Wolf Read, a consulting meteorologist for the Oregon Climate Service, concludes it was not as ‘‘great’’ as the Columbus Day Storm of 1962, which still holds state wind records in most places. But it probably outclasses all other Oregon storms in duration, with a four-day high-wind profile.
Read used wind records at the Astoria Regional Airport to make comparisons.
On Dec. 2 through Dec. 3, peak gusts striking Astoria were 85 miles per hour, higher on some headlands, and average seas were 40 feet high. Columbus Day winds hit 96 mph.
Read is working on a project for the Oregon Climate Service called ‘‘The Storm King: Historical Weather Events in the Pacific Northwest.’’ His name for the December storm, the ‘‘Great Coastal Gale’’ draws from the ‘‘Great Gale’’ of 1880, also one of Oregon’s biggest storms.
Read advised foresters at a recent meeting on how to plant tree stands to mitigate blowdown. With winds in the 40 mph range, he said, North Coast trees do best in tighter tree stands with relatively stout trees running in long swaths from north to south. Southern and southwestern boundaries of the tree stands should be protected because that’s where most storms come from, he said. But much stronger winds hit the coast every 20 to 40 years.
‘‘It’s difficult to manage for those winds,’’ he said.
‘‘It looks like Clatsop County bore the brunt of this one,’’ he said. ‘‘Pacific County (Wash.) really got hammered, too.’’
Glenn Ahrens, an Oregon State University extension forester in Astoria, said knowing the wind patterns on the coast is an important to forest planning.
‘‘If we knew these winds were going to blow every 30 years, we might have planted stouter trees with better spacing to protect them,’’ said Ahrens. In the December storm, wind speed in Astoria ranged from 32 miles per hour to 54 mph for three days, Read said. The storm qualifies as ‘‘tropical force,’’ just short of a hurricane, which is defined as a storm with sustained winds of 74 mph or higher.
‘‘But the duration here, from what I can see, is probably unprecedented,’’ he said. A key difference between the storms is the area they covered, said Read. The Columbus Day Storm covered ‘‘a broad swath’’ with ‘‘a really short impulse of extreme winds,’’ he said, while the December Storm was ‘‘focused on a narrow coastal strip.’’ In the Columbus Day Storm, an area of 75,000 to 90,000 square miles had high winds, and 25 to 40 percent of that area saw gusts of 90 mph our more. The December storm affected 10,000 to 15,000 square miles. About 10 to 20 percent of that faced gusts of 90 mph or more.
The December storm’s impact on a narrow strip of the coast is unusual, said Read, and it doesn’t follow the classical storm path that was well-established at the time of the Columbus Day Storm. Instead of developing southwest of the Oregon Coast and reaching maturity as it reaches the coast, the December storm developed much farther out and was weakening at landfall.
‘‘So the thing to take away from that is that it probably could have been a lot worse. It could have gone all the way into the Willamette Valley..” said Ahrens.
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Information from: The Daily Astorian, http://www.dailyastorian.com
