Montana Electronic Precipitation Map

TitleMontana Electronic Precipitation Map
Publication TypeConference Proceedings
Year of Conference2011
AuthorsFarnes, P. E., Huddleston J., and Flynn K.
Conference Name79th Annual Western Snow Conference
Series TitleProceedings of the 79th Annual Western Snow Conference
Date PublishedApril 2011
PublisherWestern Snow Conference
Conference LocationStateline, NV
KeywordsMontana, annual precipitation, Kriging, climatological stations, isohyetal, multivariate interpolation, annual precipitation

An accurate estimate of average annual precipitation (AAP) is a necessity for completing hydrologic analysis, developing stream flow statistics, or doing other related water resource planning. Tools to develop and complete such analysis are required, capable of very quickly updating AAP information as it become available, and available for widespread use without proprietary requirements. To meet such a mandate, we developed a free-ware UNIX based tool called PMAP, which allows rapid AAP estimates through universal Kriging. A case study was implemented for the state of Montana using the 1981-2010 water-year averages and a 400 m elevation grid. While there are many geo-statistical techniques to choose from in completing such analysis, the strength in our work is not necessarily the method that we selected, but rather the data supporting it. We compiled AAP estimates for over 1,400 stations across the region including 1,100 stations in Montana, and 300 adjacent to the state. We evaluated the data using a number of geostatistical analysis techniques. Isohyetal lines were set at 50 mm (2 inch) increments under 500 mm (20 inches) and 250 mm (10 inch) increments above 500 mm (20 inches). The1981-2010 AAP map (isohyets and grids) will be available through the Montana Natural Resource Information System (NRIS) web site electronically, and software will be made available from the Montana Department of Environmental Quality upon request