An Assessment of Rainfall from Hurricanes Harvey and Florence Relative to Other Extremely Wet Storms in the United States

The top 100 largest area-averaged, multiday precipitation events in the U.S. historical record for the period 1949-2018 were identified by calculating box-average precipitation using a network of observing stations with minimal missing data. Hurricane Harvey was the single largest event for an area sized 50,000 km(2) and a duration of 4 days. Rainfall associated with Hurricane Florence ranked seventh. Almost all of the top 100 events occurred in the southeastern United States or along the Pacific coast. The predominant meteorological cause (in 59% of the events) was fronts associated with extratropical cyclones, including 15% that were also associated with atmospheric rivers. Tropical cyclones were a significant cause, representing 25% of all events. The spatial locations, the seasonal distribution, and the spectrum of meteorological causes of these events are characteristics of the precipitation climatology that could be used as metrics to evaluate climate models.