November 4, 2004
Hurricanes spark memory of great NW storms past
Charley, Frances, Ivan and Jeanne weren’t very hospitable houseguests. By all accounts they trashed the place. And by the time they were through their names had made headlines all over the world.
But when those hurricanes hit Florida this summer, it got Cliff Mass thinking about the most serious storms in the Pacific Northwest. They are called mid-latitude cyclones, they come barreling up the Pacific Coast and they carry every bit as much of a wallop as the more-publicized tropical storms that routinely strike the East Coast, said Mass, a UW atmospheric sciences professor and one of the foremost experts on Northwest weather.
The classic examples of mid-latitude cyclones in this region are the Columbus Day Storm of 1962 and the Inaugural Day Storm of 1993. Both packed wind gusts well over 100 miles per hour in places, damaged thousands of homes, uprooted thousands of trees and left hundreds of thousands of people in the dark.
Northwest storms don’t have names that sound like a kindly aunt or uncle dropping in for a visit. Instead they’re known by when they happened or the havoc they created — the Jan. 29, 1929, Blowdown; the Intense Spring Gale of April 23, 1943; the Thanksgiving Day Storm of 1983.
Hurricanes are categorized on a scale of one to five, depending on wind speed and how low the atmospheric pressure drops. Only three Category Five hurricanes, which have winds of at least 155 miles per hour and can cause catastrophic damage, have ever hit the United States. There is no similar rating system for mid-latitude cyclones, but that doesn’t mean they can’t be as serious, Mass said.
“Every five or 10 years we get a big storm, and about every 20 to 25 years we get a really, really big storm,” he said. “Our storms can be the equivalent of category one, two and three hurricanes, and the Columbus Day storm was probably a category four. Our storms can be as devastating as hurricanes.”
With the rash of hurricanes this year as inspiration, Mass thought the time was right to talk about the Northwest’s powerful windstorms. He will deliver a free public lecture, Windstorms of the Pacific Northwest: The Origin and History of the Great Windstorms of the Region, at 7:30 p.m. on Monday, Nov. 15, in 130 Kane. (For more information or to register to attend the lecture, visit online at http://www.atmos.washington.edu/Masslecture.html.)
While hurricanes and mid-latitude cyclones are powerful storms, they have different energy sources, Mass said. Tropical storms and hurricanes are fueled by heat rising from the ocean and energy released as water vapor condenses into water within the storm system. The mid-latitude storms are powered by atmospheric temperature changes from north to south and, since they don’t depend on water for their energy, can be very strong inland.
He noted that “The Perfect Storm” depicted in the 2000 movie was associated with very big waves, but that as storms go “we have had many that dwarfed it.”
A big problem with mid-latitude cyclones has been accurately forecasting them, but even that is improving with better technology and better understanding of ocean and atmospheric conditions.
For instance, the Columbus Day Storm was largely a surprise to many people while the Inaugural Day Storm was well forecast, Mass said.
The better forecasting, which resulted in part from UW research and real-time weather modeling, has helped in making preparations — electric utilities, for instance, are able to get equipment and crews in position to make quick repairs.
Armed with forecasts derived from modern tools, ships avoid major storms, something they couldn’t do 40 years ago.
Mass would like to see forecasting capability improved even more. For example, he wants the federal government to place at least one Doppler radar installation somewhere on the Washington-Oregon coast to peer out at conditions over the Pacific Ocean. Learning how to use new satellite observations over the ocean also could help improve warnings for major storms. But no improvements will remove the danger posed by the cyclones that strike the Northwest.
“In these big storms, there’s always a few people killed,” he said.
“Often it’s because of falling trees. The chances are pretty small, but the danger is real.”
