National Weather Service – Precipitation Frequency Map Atlas Methodology

The original NOAA Atlas 2 precipitation frequency maps (from 1973) were created by manual cartographic methods. Riverside Technology, inc. (RTi) worked with the National Weather Service (NWS) to develop an automated methodology using GIS tools for the production of a new series of precipitation frequency maps. Parameters in the contouring of raster data were explored for visual smoothness, accuracy and processing speed. Programs were created to automate the conversion of raster data to contour lines.

Base data were reprojected and formatted for automated processing. Prototype precipitation frequency maps were created from sample data. These maps were made to replicate the standards used in the creation of the original atlas. Automated programs facilitate the rapid cartographic production required for the quantity of maps. Recommendations were made for moving the project into the final production phase.

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