North Coast and Cascades Network climate monitoring report: North Cascades National Park Service Complex; water year 2017

Larrabee, Michael

Climate and weather events define the ecological characteristics found in national parks and are key to understanding and interpreting changes in natural resources. Everyday park operations including; fire management, search and rescue, maintenance of park infrastructure, and visitor use are influenced by weather. Collecting weather data and maintaining climate records provides essential information needed to support park operations and to monitor park resources. This report summarizes climate data collected in North Cascades National Park Service Complex (NOCA) during the 2017 water year, and is part of a set of climate summary reports from seven national and historic parks in the North Coast and Cascades Network. Published in the National Park Service’s Natural Resource Data Series, annual climate summary reports are intended to provide basic data sets and data summaries in a timely manner, with minimal interpretation and analyses. We intend that the primary audience for this document will be National Park staff, especially decision makers, planners, interpreters and partners, in addition to the interested public. Climate data are presented from eleven weather stations located within North Cascades National Park Service Complex: Beaver Pass (3630’ elevation), Brown Top (5830’), Easy Pass (5270’), Marblemount (407’), Noisy Creek (6590’), Newhalem (520’), Park Creek Ridge (4600’), Ross Dam (1240’), Silver Lake (7670’), Stehekin (1270’) and Thunder Basin (4320’). Data were recorded using automated and manual instruments operated by the National Park Service and other collaborators, including the Natural Resources Conservation Service, National Oceanic and Atmospheric Administration, and National Weather Service. Monthly averages of daily average temperature are reported for all stations and monthly total precipitation is reported for nine stations. Comparisons are made to the 30-year normal (1981-2010) for Newhalem and Stehekin, two stations with long term climate records. Snow water equivalent (SWE) is reported and compared to the 30 year normal for three SNOTEL stations within the park and monthly snow depth is reported for seven stations within the park. Average annual temperatures in Water Year 2017 varied across the Cascades Range; stations on the west slope received above normal precipitation and east slope sites were below normal. Temperatures in December through May were below normal and June through September above normal. Overall, annual precipitation was above normal; however, there were periods of extreme wet and extreme dry during the water year. March was notably wet, with rainfall on 30 of 31 days in Newhalem. It was also the wettest March on record in Stehekin. Conversely, the May-September period set records for the lack of precipitation, including July and August when several stations did not have any measurable precipitation. Mountain snowpack on April 1 was above normal, buffered by a cold and wet March and April that resulted in significant late season accumulation.

North Coast and Cascades Network climate monitoring report: North Cascades National Park Service Complex; water year 2017

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