Attributes for NHDPlus Version 2.1 Catchments and Modified Routing of Upstream Watersheds for the Conterminous United States: PRISM Monthly Average Precipitation (millimeters), 2016-2017

These tabular data sets represent mean monthly precipitation (millimeters) data from 800-meter PRISM data for the years 2016 and 2017 compiled for two spatial components of the NHDPlus version 2 data suite (NHDPlusv2) for the conterminous United States; 1) individual reach catchments and 2) reach catchments accumulated upstream through the river network. This dataset can be linked to the NHDPlus version 2 data suite by the unique identifier COMID. The source data for mean monthly precipitation (Celsius) from 800-meter PRISM data was produced by the PRISM Group at Oregon State University. Units are degrees Celsius. Reach catchment information characterizes data at the local scale. Reach catchments accumulated upstream through the river network characterizes cumulative upstream conditions. Network-accumulated values are computed using two methods, 1) divergence-routed and 2) total cumulative drainage area. Both approaches use a modified routing database to navigate the NHDPlus reach network to aggregate (accumulate) the metrics derived from the reach catchment scale. (Schwarz and Wieczorek, 2018).