The Willamette Valley's Strongest
After many windstorms, claims are often made for the "biggest since Columbus Day 1962" or "strongest storm of the decade," or some variation on this theme. One of the main purposes of this website is to try to create a scientific basis for such comparisons--in essence, to create a method that is repeatable by someone wishing to dig into the data for themselves.
Which brings the discussion to Table 1, below . In terms of wind speeds, direct comparisons can be made among the Willamette Valley stations that have a long period of record: Eugene, Salem and Portland especially, with less consistent reporting for Corvallis, Aurora, Hillsboro and Troutdale. The table lists the top twenty most powerful storms for the Willamette Valley from 1950 to 2002, plus some others, and ranks them according to the strength of their averages. In cases were peak gust data were missing for some stations, the average represents the value for the available data.
Source: All peak gusts are from the National Climatic Data Center, unedited surface observation forms, unless indicated otherwise.
Table 1, notes:
Only a handful of storms stand out in this Willamette Valley ranking. Confidence is very high for the number one spot--with a rating some 27 points higher than the next strongest event, the Columbus Day Storm was clearly the major event of the last 52 years. Confidence for the number two and three spot is a little less. It is interesting that the top three events for the Willamette Valley happened within five years of each other (Oct 1962 to Oct 1967). After the top three, the exact positions of the following storms becomes increasingly uncertain as the number of like events increases, putting them closer together in the rankings. A difference of 1.0 point isn't that much, really, since it represents a change of just seven mph (assuming all seven stations had peak gust data for the time). The November 14, 1981 windstorm probably deserves the fourth ranking, and the storms that followed down to 8th spot were all major events. It is interesting that the very deep cyclone of December 12, 1995 only made 8th. Some of this may be due to the difference in wind measure compared to the earlier storms--5-second gust for many official stations in 1995 verses instant gust in the earlier storms. However, the 60.8 average contains a number of spotter reports that were most likely peak instant gust. The 7th place storm was also a very deep cyclone.
Note that there have been eight storms with a ranking of 60 and above since 1950--that makes for an average return period of 6.5 years, though as much as 14 years have passed between events. It looks like an event that reaches at least 63.5 is a "storm of the decade" potential.
If the storms were ranked by individual stations, the Columbus Day Storm would end up on top for all. This serves as a reminder about just how powerful the 1962 Big Blow was. The impact of the 1962 gale was so great that the storm, in essence, is an outlier, an event that is singularly unique--this can not be emphasized too much!
After the Columbus Day Storm, different storms generally occupy the lower rankings for each station, a mark of a random element to peak gusts (skip zones can result during storms) and probable differences in how the data were being taken.
Finally, the table above depicts just one method for ranking windstorms. Peak gust is just one important measure among characteristics like maximum sustained winds, wind direction changes and wind duration. If the duration of strong winds were factored in, some of these storms would start climbing up the ladder in comparison to others--notably the November 14, 1981 event in comparison to the top three, who's attacks were of much shorter duration. Methods can be devised to factor in high wind interval, but the process of adding in duration is quite time consuming in itself! When looking at the table above, it is easy to forget how much time is required to compile something as simple as this peak gust comparison.
 Peak gust data for storms from the 1950 to 1995 period is from the National Climatic Data Center, unedited surface observation forms, and Local Climatological Data monthly summaries (LCD mainly for Portland during the 1950-1953 timeframe, and Feb 1958). Peak gust data for storms from the 1996-to-present era are from the University of Washington archived surface observations, save February 7, 2002 and December 27, 2002 which were from METAR reports collected online from the National Weather Service, Portland and Seattle offices.
On February 18, 2003, this webpage was featured on KPTV Channel 12 News during an interview by Storm Team 12! Much thanks to Storm Team 12, and especially Mark Nelsen, for the interview and linking my webpage on the Storm Team website. I never expected such a result from this research, and was happily surprised by the interest. Thanks to all at KPTV 12.
Last Modified: February 28, 2003
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