Graph of the Day: Average Size of Largest Annual Rain or Snow Storm in the U.S., 1948-2011

2 August 2012 (PennEnvironment) – The biggest rainstorms and snowstorms are getting bigger. Not only are extreme downpours more frequent, but they are also more intense. The total amount of precipitation produced by the largest storm in each year at each station increased by 10 percent over the period of analysis, on average across the contiguous United States. This trend was most pronounced in New England and the Middle Atlantic. Connecticut, Delaware, Massachusetts, Maine, New Hampshire, New Jersey, New York, Pennsylvania, and Vermont all saw the intensity of the largest storm each year increase by 20 percent or more. The trend also occurred across the Midwest, the South and the West. In total, 43 states experienced a statistically significant increase in the amount of precipitation produced by the largest annual rain or snow storm. Only one, Oregon, recorded a significant decrease.

When It Rains, It Pours: Global Warming and the Increase in Extreme Precipitation from 1948 to 2011