Sequences of extreme temperature and humidity for design calculations

This paper reports on the development of the criteria and the procedures used to produce design sequences of near-extreme weather records for four design parameters: high and low dry-bulb temperature, high dew-point temperature, high enthalpy levels, and low wet-bulb depression. Design sequences, or groupings of actual hourly weather data, were obtained from 30-year, hourly weather records for 381 U.S. and Canadian locations. Four different extreme design sequences were determined for each parameter: the most extreme value for the period of record and the 0.4%, 1.0%, and 2.0% annual frequencies of occurrence. These design sequences were obtained from four different data window lengths: 24, 72, 120, and 168 hours. The data windows (or contiguous hourly readings) were developed using an `exclusive-overlapping' technique. In all cases, the mean value of the design variable for each data window was used to rank sequences. The time of occurrence, summary statistics of the extreme sequences, the hourly weather data in WYEC2 format for the time period of the four levels of extreme for each parameter and each location, and a computer program to select and output the desired data were produced on a CD-ROM.