Tuesday, 14 May 2002: 10:30 AM
100+ years of short-duration extreme climate events in the U.S.
The National Climatic Data Center has completed a project to key the pre-1948 U.S. daily cooperative data. For the first time, all of these data, dating back to the 1890s, are in digital form. Although quality control of these data is ongoing, a preliminary examination of U.S. trends in short-duration extreme events has revealed several interesting features. Several types of extreme events were studied, including heavy precipitation, heat waves, cold waves, and growing season length. Heavy precipitation events occurred almost as frequently at the beginning of the 20th Century as they did in the latter 2 decades of the 20th Century, suggesting that the potential magnitude of natural variability is quite significant with respect to recent trends. With regard to heat waves, the 1930s experienced by far the greatest frequency. The frequency prior to the 1930s was similar to the most recent 2 decades. The peak frequency of moderately-intense cold waves occurred in the decade of 1910-1920, while the frequency of the most intense cold waves was higher in the 1980s. Finally, growing season length was shorter by 10-15 days around the turn of the 20th Century, as compared to the past decade.