Heavy rainfall trends across the U.S.

Desdemona Despair

11 April 2018 (Climate Central) – With flooding in parts of the Mississippi Valley and a strong Pacific storm coming into the Northwest, we examined the trend in the number of days each year with heavy precipitation at 244 individual sites in the U.S. This expands our nationwide-averaged heavy precipitation analysis from earlier this year, complementing the 2017 Climate Science Special Report which indicated the heaviest precipitation events are increasing in all regions of the U.S.

Methodology

For each location, we examined the number of calendar days each year that had more than 0.25, 0.50, 1, and 2 inches of rain (or liquid equivalent) from 1950 to 2017. For arid climates, we displayed the trends in those lower three thresholds. Locations that did not average one 2”+ rain event every two years were defined as arid. Trends in 0.50, 1, and 2 inches were displayed for moderate and wetter climates. For clarity, we have omitted the scatter plots for each year and displayed only the linear trend. Precipitation amounts are highly variable, so not all markets have positive trends in all thresholds. [more]

Heavy Rainfall Trends Across the U.S.