William A. Gallus, Jr., Department of Geological and Atmospheric Sciences, Iowa State University


The North Atlantic Oscillation (NAO) is caused by the difference in strengths between the subtropical high and the polar low. The differing strengths between the high and low cause a fluctuating pressure gradient over the north Atlantic which can affect weather thousands of miles away, from Europe, to the Middle East, to the United States. In the eastern United States, a positive index (large pressure gradient) brings milder weather while a negative index (small pressure gradient) brings colder weather with more snow. This study was done to see the effects of the NAO on snow in the Midwest to see if the pattern was like the east coast. Eleven locations were selected with daily and monthly snowfall and NAO index data. Several statistical tests were run to find any correlation and statistical significances between the two variables. After the tests, both the daily and monthly data showed a negative correlation with the monthly data having a slightly stronger correlation; however, the location in the region with the best results was shifted west when looking at the monthly results. This shows that the North Atlantic Oscillation does impact snowfall in the Midwest with storms being more frequent or producing more snow when the NAO index is negative.

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Alek Balvanz


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