Revisiting the Statewide Climate Extremes for the United States: Evaluating Existing Extremes, Archived Data, and New Observations

New all-time extreme climate records have been set in several states over the past few years. These records highlighted a need to review the existing statewide climate extremes tables maintained by the NOAA National Climatic Data Center (NCDC). Also, since these tables were last updated, NCDC has greatly extended its digital data record into the past for many locations and has applied imprmied quality assurance processes to its archived data, revealing several potential new record values. To ensure the records maintained in the statewide climate extremes tables accurately reflect the most current and valid data available, the records were reevaluated. The all-time maximum and minimum temperature, all-time greatest 24-h precipitation and snowfall, and all-time greatest snow depth for each of the 50 states, Puerto Rico, and the U.S. Virgin Islands were manually examined to determine their validity, accuracy, accessibility, and provenance. NCDC's data holdings were scoured for values that might exceed established records, and the validity of each potentially record-breaking observation was evaluated. The revised extremes tables were vetted by the National Weather Service, regional climate centers, and state climatologists to ensure agreement. In conjunction with this revision, a new state climate extremes evaluation process has been established to formally consider any potential challenges to the existing records and update the records tables as necessary.