The Willamette Valley's Strongest Windstorms 1950-2002 compiled by Wolf Read

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 [1]. 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.

The Willamette Valley's Top Windstorms 1950-2002: Peak Gusts Rank Date Eugene Corvallis Salem Aurora Hillsboro Portland Troutdale Average 1 12OCT1962 86 127 90 MM 90 [5] 104 E 106 100.5 2 27MAR1963 75 81 68 MM MM 62 81 73.4 3 02OCT1967 58 77 E 68 MM 67 78 63 68.5 4 14NOV1981 58 MM 71 MM 63 71 MM 65.8 5 07JAN1961 81 58 60 MM MM 55 MM 63.5 6 22DEC1955 63 70 56 MM MM 62 MM 62.8 7  04DEC1951 70 72 52 MM MM 74 [7] 40 [11] 61.6 8 12DEC1995 49 MM 59 60 [4] 65 [6] 74 [8] 58 60.8 9 24FEB1958 62 MM 58 MM MM 61 MM 60.3 10  15JAN1951 60 42 [1] 52 MM MM 54 80 E 57.6 11 01MAR1974 60 MM 61 MM 47 64 55 57.4 12 28FEB1955 40 46 E 47 MM MM 76 72 E 56.2 13 05APR1972 39 76 60 MM 40 63 58 56.0 14 09JAN1953 53 45 60 MM MM 56 [9] 65 E 55.8 15 07JAN1990 58 MM 61 MM 36 63 MM 54.5 16 16DEC1961 58 46 E 55 MM MM 58 MM 54.3 17 14APR1957 52 60 [2] 48 MM MM 69 42 [12] 54.2 18 07JAN1953 58 65 E 55 MM MM 49 [10] 38 [13] 53.0 19 26MAR1971 49 43 58 MM 39 71 MM 52.0 20 19JAN1964 51 63 E 46 MM MM 48 MM 52.0 21 11JAN1988 52 MM 60 MM 40 53 MM 51.3 Ranking of storms increasingly uncertain after this point as frequency of events increases. 22? 15DEC1977 48 MM 52 MM 46 56 MM 50.5 23? 16JAN2000 39 44 60 49 43 59 51 49.3 24? 26OCT1950 45 MM 47 MM MM 66 39 49.3 25? 21DEC1955 60 58 E 48 MM MM 40 36 48.4 26? 24NOV1983 46 MM 54 MM 46 46 47 47.8 Some events of interest, many from the recent past. ?? 24FEB1961 72 46 31 MM MM 37 MM 46.5 ?? 03MAR1999 52 43 46 43 44 51 44 46.1 ?? 01JAN1997 53 49 46 MM 35 51 35 [14] 44.8 ??  03NOV1958 44 30 [3] 38 MM MM 71 MM 43.8 ?? 20JAN1993 41 MM 51 MM 40 43 38 42.6 ?? 27DEC2002 39 46 37 43 46 39 40 41.4 ?? 07FEB2002 70 44 31 33 22 31 29 37.1

Table 1, notes: "E" denotes a reading estimated through various, sometimes undefined, means. [1] Highest gust observed. No observations before 08:00 on Jan 15, so actual peak probably unrecorded. [2] Peak gust extrapolated from a peak 46 mph 1-minute wind using a standard 1.3 gust factor. [3] Peak gust extrapolated from a peak 23 mph 1-minute wind using a standard 1.3 gust factor. [4] This is a spotter report from Canby. [5] Peak gust made on direct reading wind equipment at the Hillsboro Airport early in the storm. A stronger gust a moment later destroyed the hanger roof on which the anemometer sensor was located, ending wind readings. From: Harper, Byron P., "Report on the October 12 Wind Storm," Bonneville Power Administration Power Operations Branch Forecasting Unit, October 31, 1962. [6] This is an unofficial peak gust at Beaverton. On the official SWO forms for the Hillsboro Airport, the peak gust was a mere 37 mph! Considering the spotter reports from the area, the official reading of 37 mph is likely low. [7] Apparently peak gust recorders registered 74 mph (source, National Weather Service, Portland, "Climate of Portland." The 74 mph gust was on the old direct reading wind equipment that had been replaced by the ASOS system, and is unofficial, according to Dave Willson, lead forecaster at NWS Portland (personal communication 2002). [8] Peak gust extrapolated from a reported peak fastest mile of 57 mph using a standard 1.3 gust factor. [9] Peak gust extrapolated from a reported peak fastest mile of 43 mph using a standard 1.3 gust factor. [10] Peak gust extrapolated from a reported peak fastest mile of 38 mph using a standard 1.3 gust factor. [11] Highest gust available--readings missing between 11:27 and 20:30 PST. [12] Peak gust extrapolated from a peak 32 mph 1-minute wind using a standard 1.3 gust factor. [13] Highest gust reported during limited observation times. [14] Highest gust reported during limited observation times.

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.

References [1] 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.

Special Note 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 Page Created: January 29, 2003 You can reach Wolf via e-mail by clicking here. | Back |