Winter is the fastest warming season east of the Mississippi River, with hotspots of winter warming (greater than +2.5°C since 1970) concentrated in the northeastern United States. Over the past century, the region has lost 2-3 weeks of sustained winter conditions across both low elevations and some montane areas. Importantly for atmospheric deposition estimation, shifts in snow vs. rain can affect deposition of important analytes such as mercury and nitrogen. Further, most snow measurements in the Northeast are from low-elevation weather stations in populated areas, resulting in gaps of snowpack and weather observations across elevational gradients and in remote areas, with fewer than 5% of all manual and automated stations at higher elevation (>823 m). Due to the challenges of collecting snow in NADP/MDN collectors, particularly in mountainous terrain, winter deposition via snow can be over- or under-estimated. In the western U.S., the NRCS Snow Telemetry (SNOTEL) network monitors snowpack, weather, and other climate elements at over 900 automated stations and provides critical data for hydrological monitoring and water resource management that can enhance context for NADP measurements. In the Eastern U.S., the Northeast Snow Survey (NESS) Feasibility Study is informed by Federal, State, Tribal, and NGO interest-holder engagement to develop priorities for snowpack and weather monitoring and will design a proposed station network and supporting operations that could similarly help refine deposition estimates. For example, interest holders identified a need for snowpack depth and water equivalent measurements along elevational gradients, to fill spatial gaps and better quantify mountain snowpack. Since stations operate year-round, they could potentially help quantify both liquid and solid precipitation across the Northeast and aid in modeling and validation studies of atmospheric deposition. The multi-institution leadership team working in collaboration with USDA-NRCS is also identifying current data resources and gaps to inform network planning through a data survey to collate snowpack and weather data in the region. We will use a systems engineering approach to refine objectives, map our network design. By including input from interest holders in the feasibility study, NESS aims to develop plans for a sustainable network that supports a range of objectives from flood forecasting and resource management to furthering modeling and scientific studies.

¹ Appalachian Mountain Club, Gorham, NH

² University of Vermont, Burlington, VT

³ University of New Hampshire, Durham, NH

⁴ USDA NRCS Utah Snow Survey, Salt Lake City, UT

⁵ USDA NRCS National Water and Climate Center, Portland, OR

⁶ New York State Mesonet and SUNY-Albany, Wilmington, NY

⁷ Schoodic Institute, Winter Harbor, ME

⁸ Radically Simple Consulting, Denver, CO

* Corresponding author: snelson@outdoors.org