Extreme Precipitation Events Observed by the U.S. Climate Reference Network

The U.S. Climate Reference Network consists of 114 stations in the conterminous U.S. that observe temperature, precipitation, soil moisture/temperature and ancillary variables at a 5-minute temporal resolution with research quality instrumentation. The precipitation data have been summed into running totals ranging from 5 minutes to 30 days in length and compared to 1-year, 2-year, and 5-year return interval precipitation thresholds for station locations from NOAA Atlas 14. Over the conterminous U.S. area covered by NOAA Atlas 14, USCRN stations detect the occurrence of a greater number of exceedances than would be expected at time intervals less than 1 day in length during their period of record (2005-2016). It is hypothesized that USCRN stations are better able to measure the true precipitation event maxima at time periods less than one day in length, given the high temporal resolution of the observations. Conversely, the USCRN observes fewer heavy rain events of longer duration than predicted by Atlas 14. This is likely due to the much better spatial coverage of the daily stations underlying the calculation of Atlas 14 return interval thresholds at daily and longer time intervals. It is also possible that a trend in extreme precipitation event counts is already being seen in the recent USCRN observations; precipitation extremes will continue to be explored over the life span of the network.