Spatial and Temporal Analysis of Extreme Midwestern Blizzard Storm Tracks and Subsequent Federal Disaster Declarations

Ph.D. Dissertation, University of Kansas, 26 April 2010

Christopher John Atkinson

“Using the NOAA Central Library United States Daily Weather Maps Project, the Hydrometeorological Prediction Center (HPC) online weather charts, Storm Data records from the National Climatic Data Center (NCDC), and the Academic OneFile from the University of Kansas, this study identified 145 extreme Midwestern blizzards, defined as storms with minimum central pressures at or below 992 mb, occurring between September 1, 1966, and May 31, 2008. This 42–year time period was split into two 21–year segments for comparative analyses of any changes in the spatial and temporal character of these storms: 1) September 1, 1966–May 31, 1987 (Time Period I: 79 blizzards); and, 2) September 1, 1987–May 31, 2008 (Time Period II: 66 blizzards). Changes in the frequency and intensity of extreme Midwestern blizzards proved to be statistically insignificant. All 145 blizzards in Time Periods I and II were mapped using ArcGIS 9.3 with data from the GISS Atlas of Extratropical Storm Tracks and the HPC weather maps and charts online resource. A 50–km buffer flanked each storm track and helped account for any uncharted errors in the original re–analysis procedures done by the GIS. Additionally, the 50–km buffer provided a construct for identifying the trajectory for each snowstorm within the 12–state study region, defined as North Dakota, South Dakota, Nebraska, Kansas, Missouri, Iowa, Minnesota, Wisconsin, Michigan, Illinois, Indiana, and Ohio. This study indicated a statistically insignificant southward shift of the median storm track in Time Period II. Of the 79 blizzards in Time Period I and the 66 blizzards in Time Period II, only 23 storms (6 in Time Period I and 17 in Time Period II) resulted in federal emergency and disaster declarations (FEDD). Logistic regression analyses of seven independent variables utilizing the Forward LR model failed to accurately predict when federal declarations occurred. In contrast, the total number of counties declared as FEDDs increased from 378 (Time Period I) to 973 (Time Period II), a statistically significant difference. The spatial distribution of declaration hazards (snow and ice) contributing to FEDDs changed between the two time periods, indicating a pattern not necessarily connected to the expected climatology of extreme Midwestern blizzards.”

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