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Revisiting the Statewide Climate Extremes

This Monthly Weather Review map of maximum snow depth in February 1895. This map, coupled with a map of February's low pressure tracks, climatological data publications, and various contemporary photographs helped to corroborate a 24-inch snow depth observation at Rayne, Louisiana on 15 February 1895—part of the "St. Valentine's Day blizzard" that impacted the Gulf Coast that year.

While NCDC has maintained records of extreme climate events for years, statewide records had not undergone an extensive review and evaluation since 2003. Three years ago, NCDC began to manually evaluate the existing records for each state to determine their validity, accuracy, accessibility, and background.

Over the past few years, several states set new all-time extreme climate records. These new records highlighted the need to review these existing statewide climate extremes tables. Also, since these tables were last updated, NCDC has greatly extended its digital data record into the past for many locations and has applied improved quality assurance processes to its archived data.

These climate extremes records include the all-time maximum and minimum temperature, the all-time greatest 24-hour precipitation and snowfall, and the all-time greatest snow depth for each of the 50 states, Puerto Rico, and the U.S. Virgin Islands. NCDC examined the data for values that might exceed the established records and evaluated the validity of each potentially record-breaking observation. Then, the National Weather Service, the Regional Climate Centers, and the State Climatologists assessed the revised extremes tables to ensure agreement.

In conjunction with this revision, NCDC established a new state climate extremes evaluation process to formally consider any potential challenges to the existing records and update the records tables as necessary. An article, “Revisiting the Statewide Climate Extremes for the United States—Evaluating Existing Extremes, Archived Data, and New Observations,” has been accepted for publication in the Bulletin of the American Meteorological Society and describes the process NCDC undertook to update these records. NCDC’s Karsten Shein collaborated with Dennis Todey (South Dakota Office of Climatology), Adnan Akyuz (North Dakota State University), James Angel (Illinois Office of the State Climatologist), Timothy Kearns (NOAA NWS WFO Aberdeen), and James Zdrojewski (NOAA NWS Climate Services Division) to ensure these valid climate extremes for each state and in the creation of this paper.