PUBLICATION HIGHLIGHT: What history tells us about the 2015 U.S. daily rainfall extremes

Impassable roadway in San Marcos, Texas (June 3, 2015). Extensive flooding impacted the area, resulting in a Presidentially declared disaster. Photo credit: Jocelyn Augustino/FEMA

DECEMBER 16, 2016—Three catastrophic rainfall events during 2015 caused more than $1 billion each in damages in the Texas/Oklahoma region, South Carolina, and the Mississippi Basin. A new study, by CIRES and NOAA scientists at the ESRL Physical Sciences Laboratory (PSL), provides an assessment of these high-impact events in both a national and historical context. Observations over the last century show an uptick in heavy precipitation events—many occurring in recent decades, which is consistent with model evidence that their frequency increases in response to increased carbon dioxide levels. The PSL research team was interested to learn if the 2015 events could have been anticipated by comparing them to century-long trends of extreme daily rainfall over the U.S. Their findings, published this month in a special supplement on Explaining Extreme Events of 2015 from a Climate Perspective, show that the increased number of daily rainfall extremes in 2015 fits in with national expectations, but that they were concentrated in regions and/or seasons without such upward trends.