This web page provides access and information to the annual maximum and partial duration time series data that are used in precipitation frequency analysis in NOAA Atlas 14 Volumes.
The annual maximum series (AMS) and the partial duration series (PDS) data are provided as constrained values; they were converted to unconstrained amounts before use in frequency analysis. Starting with Volume 4, only AMS data are available for download since PDS-based frequency estimates were derived from the AMS data.
For more information about water year definition, AMS and PDS data for precipitation frequency analysis, and conversion from constrained to unconstrained amounts, please read the applicable NOAA Atlas 14 document.
www.nws.noaa.gov 
