Evaluation and verification of statewide climate extremes records

NOAA's National Climatic Data Center (NCDC) maintains several tables of all-time record extreme values within each state. These tables include the record maximum and minimum air temperature, and greatest 24-hour precipitation amount. In addition, NCDC's United States Snow Climatology (USSC)project maintains automated tables of record snow events (e.g., greatest snow depth, greatest 24-hour snow fall) for each state. Unfortunately, the statewide extremes tables for temperature and precipitation are static, and had not been updated since 1998 for precipitation and 2003 for temperatures. The USSC database had not been updated since 2006. As a result, all of these tables were obsolete. This paper describes the efforts and methods used to bring these tables up to date. In particular, existing records were manually reevaluated for validity by NCDC, and newer record values (since 2006) were vetted by the State Climate Extremes Committee (SCEC). Where a value was found to be invalid, the historical record had to be searched to identify a valid replacement value, and in all cases, the records determined to be valid had to be reflected as such in NCDC's digital archive. Once the record values were reviewed by NCDC, they were passed to the appropriate Regional Climate Centers (RCCs) and the State Climatologists (SCs) for review and approval. Feedback from the RCCs and SCs was used to complete the revision of the extremes tables. As a result of these efforts, the tables for all-time statewide maximum and minimum temperature, greatest 24-hour precipitation, greatest 24-hr snow fall, and greatest snow depth have been updated and will continue to be maintained by the SCEC.