Friday, September 10, 2010

How our strongest storms form

September 10, 2010

3:31 P.M.

Hey everybody. I'll pick up the tab on where we left off on yesterday. I must emphasize that the contents of this blog are not my own ideas, sure I'm not copying and
pasting (except for quotes), but I'm really relying on a variety of sources
including books by Glenn Miller and Cliff Mass, and of course Wolf Read's website. So give these guys credit for allowing my knowledge to grow to the point that it has.

On October 21, 1934, one of the strongest storms on record for Seattle. A degrading but still very tightly wound and deep low headed off Tattoosh Island and delivered a solid gale into the region. This storm was not as devastating for the coast as the 1921 storm but was much more devastating for the inland areas. Puget Sound recorded waves as high
as 20 feet, and an aircraft hangar at a Boeing plant actually got lifted off of the ground.

This storm may have actually been the strongest on record for the Seattle metro area, but it was not the strongest storm to hit the Pacific Northwest. There was one storm that hit in 1962 that caused unfathomable devastation throughout the Pacific Northwest, and this was the Columbus Day storm on October 12, 1962.

How did the Columbus Day Storm form? Well, like many of our absolute strongest storms, it had a very ample supply of moisture. In this case, the moisture actual
ly had a tropical source and was the remains of Typhoon Freda in the Pacific. The storm held this moisture as it was carried along the jetstream into our area of the woods, and as it got close, it sped up, turned northward (it had been previously going wes
t southwestward), and intensified into a compact, intense mid-latitude s

The Columbus Day Storm is the Holy Grail of all windstorms, and the storm that all others are compared to. Cape Blanco on the Oregon Coast recorded sustained winds of 145 miles per hour, Category-4 hurricane force. Most estimates pin gusts there at 179 mph, and I've seen one estimate at 195. Similar wind speeds were observed at exposed locations in Oregon and Washington such as the Tillamook Forest, the Mt. Hebo radar site, and Naselle Ridge. Even areas that were far inland received high gusts. Corvallis had a gust to 127. Portland had a gust to 116. Redmond had a gust to 100. And no, these amounts are not in km/h. There was over 10 billion board feet of timber blown down, and many 1000-year trees were blown down. What does that mean? That the Columbus Day storm could have been the event of the millennium. Nothing since the Columbus Day Storm has even come close in the strength of winds throughout such a wide area.

Pictures are of Corvallis (top) and Portland. Although Washington was also hard hit, Oregon took the brunt of the storm.

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