This data release supports the study by Sexstone and others (2019) and contains simulation output from a hydrological modeling experiment using a specific calibration of the conterminous United States (CONUS) application of the Precipitation-Runoff Modeling System (PRMS) (Hay, 2019) as implemented in the National Hydrologic Model (NHM) infrastructure (Regan and others, 2018). The by hydrologic response unit (byHRU) calibrated, baseline version of the NHM-PRMS (Hay, 2019) was used to evaluate the sensitivity of simulated runoff to the representation of snow depletion curves (SDCs) within the NHM-PRMS across the CONUS. The model experiment consisted of seven NHM-PRMS model simulations using the calibrated NHM-PRMS model parameters from Hay (2019). For each of the model simulations, the calibrated SDCs (Hay, 2019) were replaced with a single derived SDC derived based on a lognormal probability distribution function and assigned snow water equivalent coefficient of variation (CV) value. The seven CV values ranged from 0.1 to 2.0. Each of the simulations were completed at a daily time-step over a 14-year period (water years 2003 – 2016). Detailed methods and results are provided in Sexstone and others (2019). The SDC parameters used in this model experiment are provided by this data release. Furthermore, the attached NHM-PRMS variable table lists the selected output variables included in this data release. The individual *.csv files follow a naming convention of nhru_variable name_CVX.X.csv. The variable names included are defined further in NHM-PRMS variable table. The “CVX.X” denotes the CV value that was used to derive the SDC for the model simulation. The structure of each output file includes a header line which labels the columns by the HRU identification number with each row providing daily outputs. An inventory of the files provided within this data release can be found below. This research used resources provided by the Core Science Analytics, Synthesis, & Libraries (CSASL) Advanced Research Computing (ARC) group at the U.S. Geological Survey. Inventory of data release: NHM-PRMS_SDC_study.xml (1 .xml file): FGDC-compliant metadata file for the data release files. SDC_params.csv (1 .csv file): Table of the seven snow depletion curve parameterizations used in the modeling study. NHM-PRMS_variable_table.docx (1 .docx file): Table describing the selected NHM-PRMS output variables provided in this data release. nhru_gwres_flow_CVX.X.csv (7 .csv files): NHM-PRMS groundwater discharge output for water years 2002 through 2016. Each of the 7 .csv files are labeled with the coefficient of variation (CV) value for the snow depletion curve that was used in the model simulation. nhru_hru_actet_CVX.X.csv (7 .csv files): NHM-PRMS actual evapotranspiration output for water years 2002 through 2016. Each of the 7 .csv files are labeled with the coefficient of variation (CV) value for the snow depletion curve that was used in the model simulation. nhru_hru_outflow_CVX.X.csv (7 .csv files): NHM-PRMS total flow output for water years 2002 through 2016. Each of the 7 .csv files are labeled with the coefficient of variation (CV) value for the snow depletion curve that was used in the model simulation. nhru_hru_ppt_CVX.X.csv (7 .csv files): NHM-PRMS precipitation output for water years 2002 through 2016. Each of the 7 .csv files are labeled with the coefficient of variation (CV) value for the snow depletion curve that was used in the model simulation. nhru_pkwater_equiv_CVX.X.csv (7 .csv files): NHM-PRMS snow water equivalent output for water years 2002 through 2016. Each of the 7 .csv files are labeled with the coefficient of variation (CV) value for the snow depletion curve that was used in the model simulation. nhru_potet_CVX.X.csv (7 .csv files): NHM-PRMS potential evapotranspiration output for water years 2002 through 2016. Each of the 7 .csv files are labeled with the coefficient of variation (CV) value for the snow depletion curve that was

Climate change information simulated by global climate models is downscaled using statistical methods to translate spatially course regional projections to finer resolutions needed by researchers and managers to assess local climate impacts. Several statistical downscaling methods have been developed over the past fifteen years, resulting in multiple datasets derived by different methods. We apply a simple monthly water-balance model (MWBM) to demonstrate how the differences among these datasets result in disparate projections of snow loss and future changes in runoff. We apply the MWBM to six statistically downscaled datasets for 14 general circulation models (GCMs) from the Climate Model Intercomparison Program Phase 5 (CMIP5) for the RCP 8.5 emission scenario (1950 - 2099). The statistically downscaled datasets are as follows: BCCA: Bias Corrected Constructed Analogs (Reclamation, 2013) BCSD-C: Bias Corrected Spatial Disaggregation (Reclamation, 2013) BCSD-F: Bias Corrected Spatial Disaggregation (Thrasher et al., 2013) LOCA: Localized Constructed Analogs (Pierce et al., 2014) MACA-L: Multivariate Adaptive Constructed Analogs (Abatzoglou & Brown, 2012, bias corrected by Livneh et al., 2013) MACA-M: Multivariate Adaptive Constructed Analogs (Abatzoglou & Brown, 2012, bias corrected by METDATA, Abatzoglou, 2013) Users interested in the downscaled temperature and precipitation files are referred to the dataset home pages: BCCA, BCSD-C: http://gdo-dcp.ucllnl.org/downscaled_cmip_projections/dcpInterface.html BCSD-F: https://cds.nccs.nasa.gov/nex/ LOCA: http://loca.ucsd.edu/ MACA-L, MACA-M: http://maca.northwestknowledge.net The GCMs are the following: bcc-csm1-1, CanESM2, CNRM-CM5, CSIRO-Mk3-6-0, GFDL-ESM2G, GFDL-ESM2M, inmcm4, IPSL-CM5A-LR, IPSL-CM5A-MR, MIROC-ESM, MIROC-ESM-CHEM, MIROC5, MRI-CGCM3, NorESM1-M

Climate change information simulated by global climate models is downscaled using statistical methods to translate spatially course regional projections to finer resolutions needed by researchers and managers to assess local climate impacts. Several statistical downscaling methods have been developed over the past fifteen years, resulting in multiple datasets derived by different methods. We apply a simple monthly water-balance model (MWBM) to demonstrate how the differences among these datasets result in disparate projections of snow loss and future changes in runoff. We apply the MWBM to six statistically downscaled datasets for 14 general circulation models (GCMs) from the Climate Model Intercomparison Program Phase 5 (CMIP5) for the RCP 8.5 emission scenario (1950 - 2099). The statistically downscaled datasets are as follows: BCCA: Bias Corrected Constructed Analogs (Reclamation, 2013) BCSD-C: Bias Corrected Spatial Disaggregation (Reclamation, 2013) BCSD-F: Bias Corrected Spatial Disaggregation (Thrasher et al., 2013) LOCA: Localized Constructed Analogs (Pierce et al., 2014) MACA-L: Multivariate Adaptive Constructed Analogs (Abatzoglou & Brown, 2012, bias corrected by Livneh et al., 2013) MACA-M: Multivariate Adaptive Constructed Analogs (Abatzoglou & Brown, 2012, bias corrected by METDATA, Abatzoglou, 2013) Users interested in the downscaled temperature and precipitation files are referred to the dataset home pages: BCCA, BCSD-C: http://gdo-dcp.ucllnl.org/downscaled_cmip_projections/dcpInterface.html BCSD-F: https://cds.nccs.nasa.gov/nex/ LOCA: http://loca.ucsd.edu/ MACA-L, MACA-M: http://maca.northwestknowledge.net The GCMs are the following: bcc-csm1-1, CanESM2, CNRM-CM5, CSIRO-Mk3-6-0, GFDL-ESM2G, GFDL-ESM2M, inmcm4, IPSL-CM5A-LR, IPSL-CM5A-MR, MIROC-ESM, MIROC-ESM-CHEM, MIROC5, MRI-CGCM3, NorESM1-M

This dataset is part of the National Water Census ongoing development of best estimates of daily historical water budgets for over 100,000 hydrologic units across the United States. In this release, estimates of total flow and snowmelt for each hydrologic unit are added to the already released estimates of actual evapotranspiration, snowpack water-equivalent storage, soil moisture, recharge, streamflow, and precipitation. All these estimates are made available per twelve-digit hydrologic unit code watershed as contained in the NHDPlus v2.1 dataset and associated Watershed Boundary Dataset (WBD) snapshot. As this project progresses, it is expected that a complete closed water budget generated from the same water budget model will succeed this data release. Users are advised to ignore the first two years of the simulations to account for model initialization.

For background on source data and generation of these water budget variables, see nhru_hru_outflow.csv and nhru_snowmelt.csv from:

Hay, L.E. and LaFontaine, J.H., 2020, Application of the National Hydrologic Model Infrastructure with the Precipitation-Runoff Modeling System (NHM-PRMS), 1980-2016, Daymet Version 3 calibration: U.S. Geological Survey data release, https://doi.org/10.5066/P9PGZE0S

The water budget variables were converted to a HUC12 basis using area-weighted spatial interpolation. The HUC12 version is the one included with WBD snapshot associated withe NHDPlus v2.1. All code used for conversions are published by Blodgett (2020) referenced below.

Summary of files included:
1) hu12_ids.csv.zip - twelve digit hydrologic unit (HUC12) code identifiers used in all files.
2) timesteps.csv.zip - timesteps used in all files.
3) nhm_total_flow_timeseries.csv.zip - One HUC12 per row, one date per column, version of total flow data.
4) nhm_snowmelt_timeseries.csv.zip - One HUC12 per row, one date per column, version of snowmelt data.

This data release compliments the following related data releases:

Actual evapotranspiration and snowpack water equivalent storage:
Blodgett, D.L., 2020, Twelve-digit hydrologic unit actual evapotranspiration and snowpack water equivalent storage from the National Hydrologic Model Infrastructure with the Precipitation-Runoff Modeling System 1980-2016: U.S. Geological Survey data release, https://doi.org/10.5066/P9IH7CB8.

Soil moisture and recharge:
Blodgett, D.L., 2019, Twelve digit hydrologic unit soil moisture and recharge from the National Hydrologic Model Infrastructure with the Precipitation-Runoff Modeling System: U.S. Geological Survey data release, https://doi.org/10.5066/P9ZZAWK4.

Streamflow:
Russell, A.M., Over, T.M., and Farmer, W.H., 2018, Statistical daily streamflow estimates at HUC12 outlets in the conterminous United States, Water Years 1981-2017: U.S. Geological Survey data release, https://doi.org/10.5066/P9DPSY6G.

Precipitation:
https://www.sciencebase.gov/catalog/item/52a7bed0e4b0de1a6d2dd0fd
Thornton, P.E., Thornton, M.M., Mayer, B.W., Wei, Y., Devarakonda, R., Vose, R.S., and Cook, R.B., 2017, Daymet—Daily surface weather data on a 1-km grid for North America, Version 3: ORNL DAAC website, accessed March 8, 2017, at https://doi.org/10.3334/ORNLDAAC/1328.

This dataset is part of the National Water Census ongoing development of best estimates of daily historical water budgets for over 100,000 hydrologic units across the United States. In this release, estimates of total flow and snowmelt for each hydrologic unit are added to the already released estimates of actual evapotranspiration, snowpack water-equivalent storage, soil moisture, recharge, streamflow, and precipitation. All these estimates are made available per twelve-digit hydrologic unit code watershed as contained in the NHDPlus v2.1 dataset and associated Watershed Boundary Dataset (WBD) snapshot. As this project progresses, it is expected that a complete closed water budget generated from the same water budget model will succeed this data release. Users are advised to ignore the first two years of the simulations to account for model initialization.

For background on source data and generation of these water budget variables, see nhru_hru_outflow.csv and nhru_snowmelt.csv from:

Hay, L.E. and LaFontaine, J.H., 2020, Application of the National Hydrologic Model Infrastructure with the Precipitation-Runoff Modeling System (NHM-PRMS), 1980-2016, Daymet Version 3 calibration: U.S. Geological Survey data release, https://doi.org/10.5066/P9PGZE0S

The water budget variables were converted to a HUC12 basis using area-weighted spatial interpolation. The HUC12 version is the one included with WBD snapshot associated withe NHDPlus v2.1. All code used for conversions are published by Blodgett (2020) referenced below.

Summary of files included:
1) hu12_ids.csv.zip - twelve digit hydrologic unit (HUC12) code identifiers used in all files.
2) timesteps.csv.zip - timesteps used in all files.
3) nhm_total_flow_timeseries.csv.zip - One HUC12 per row, one date per column, version of total flow data.
4) nhm_snowmelt_timeseries.csv.zip - One HUC12 per row, one date per column, version of snowmelt data.

This data release compliments the following related data releases:

Actual evapotranspiration and snowpack water equivalent storage:
Blodgett, D.L., 2020, Twelve-digit hydrologic unit actual evapotranspiration and snowpack water equivalent storage from the National Hydrologic Model Infrastructure with the Precipitation-Runoff Modeling System 1980-2016: U.S. Geological Survey data release, https://doi.org/10.5066/P9IH7CB8.

Soil moisture and recharge:
Blodgett, D.L., 2019, Twelve digit hydrologic unit soil moisture and recharge from the National Hydrologic Model Infrastructure with the Precipitation-Runoff Modeling System: U.S. Geological Survey data release, https://doi.org/10.5066/P9ZZAWK4.

Streamflow:
Russell, A.M., Over, T.M., and Farmer, W.H., 2018, Statistical daily streamflow estimates at HUC12 outlets in the conterminous United States, Water Years 1981-2017: U.S. Geological Survey data release, https://doi.org/10.5066/P9DPSY6G.

Precipitation:
https://www.sciencebase.gov/catalog/item/52a7bed0e4b0de1a6d2dd0fd
Thornton, P.E., Thornton, M.M., Mayer, B.W., Wei, Y., Devarakonda, R., Vose, R.S., and Cook, R.B., 2017, Daymet—Daily surface weather data on a 1-km grid for North America, Version 3: ORNL DAAC website, accessed March 8, 2017, at https://doi.org/10.3334/ORNLDAAC/1328.

This data release contains three variables from the National Hydrologic Model Infrastructure with the Precipitation-Runoff Modeling System (NHM-PRMS) version 1.1 modeling application forced with CONUS404-BA (Markstrom and others, 2024) from January 1st, 1980 through September 25th, 2021 that are summarized to a twelve-digit hydrologic unit code for the spatial extent of the conterminous United States at a daily timestep. The three variables presented here are snow water equivalent, actual evapotranspiration, and soil moisture fraction. There are three netCDF files of daily, modeled data; one for each of the following variables: actual evapotranspiration - "huc12_daily_nhmprms-conus404ba_actet.nc", soil moisture fraction - "huc12_daily_nhmprms-conus404ba_soil_moisture_fraction.nc", and snow water equivalent - "huc12_daily_nhmprms-conus404ba_pkwater_equiv.nc". Additionally, two supplementary files are also included in this data release. The first file (“weights_hru_to_huc12_nhmprms_conus404ba.csv”) contains the spatial weights or fraction that is used to “weight” the modeling output in the area-weighting process. The second file (“summed_weights_per_huc12_nhmprms_conus404ba.csv”) contains the total fractional area within each twelve-digit hydrologic unit code that is covered by the modeling output and is important for filtering results in the data file (where a fractional coverage may be less than one).

This data release supports the study by Sexstone and others (2020) and contains simulation output from SnowModel (Liston and Elder, 2006), a well-validated process-based snow modeling system. Simulations are for water years 1984 through 2017 (October 1, 1983 through September 30, 2017) across a 11,200 square kilometer model domain in the San Juan Mountains of southwestern Colorado, United States that encompasses the Rio Grande Basin headwaters (HUC8 13010001). This data release also contains supporting field-based snow and meteorological station observations collected within the model domain during water years 2016 and 2017 that were used to evaluate SnowModel simulations. Sexstone and others (2020) provide details and summarize findings from the SnowModel simulations and supporting observations. SnowModel simulation output provided in this data release are stored in NetCDF files that have spatial (100-meter [m] grid resolution) and temporal (yearly) dimensions. Simulated SnowModel annual snow metrics (water years 1984 through 2017) in the attached NetCDF files include: mean winter (1 October to 31 May) air temperature (T; degrees Celsius [°C]), cumulative winter precipitation (P; millimeters [mm]), peak snow water equivalent (SWE; mm), SWE:P (ratio of peak SWE to winter P; m/m), snow-covered days (days with snow on the ground; days), total snowmelt (surface-water input into the soil that occurs when SWE greater than [>] 0; mm), snowmelt rate (rate the snow melts from peak SWE to melt out; millimeter per day [mm/day]), SM50 (water year day following peak SWE when half of snowpack has melted), peak SWE timing (water year day when peak SWE occurs), melt-out timing (water year day when snow melt out occurs), sublimation (total snow sublimation including surface, canopy, and blowing snow components; mm), sublimation:P (total snow sublimation to winter P ratio; m/m), 1 March SWE (mm), 1 April SWE (mm), 1 May SWE (mm), and 1 June SWE (mm). Supporting observations are provided in this data release in comma separated value (csv) files. Supporting meteorological station observations from three meteorological stations (daily mean values for the previous day) include: air temperature (°C), relative humidity (percent [%]), wind speed (meter per second [m/s]), incoming shortwave radiation (watts per meter squared [W m-2]), net radiation (W m-2), and albedo. Supporting field-based snow observations collected at 73 locations at a daily temporal dimension include: SWE (mm), standard deviation of SWE (mm), snow depth (m), and standard deviation of snow depth (m). An inventory and description of each of the files attached to the data release is provided below. Inventory of data release: URGB_SnowModel_study.xml: FGDC-compliant metadata file for the data release files. melt_doy.nc: NetCDF file of annual melt-out timing (water year day when snow melt out occurs) from SnowModel output . melt_rate.nc: NetCDF file of annual snowmelt rate (rate the snow melts from peak SWE to melt out; mm/day) from SnowModel output. peak_swe.nc: NetCDF file of annual peak SWE (mm) from SnowModel output. peak_swe_doy.nc: NetCDF file of annual peak SWE timing (water year day when peak SWE occurs) from SnowModel output. SM50.nc: NetCDF file of annual SM50 (water year day following peak SWE when half of snowpack has melted) from SnowModel output. snow_days.nc: NetCDF file of annual snow-covered days (days with snow on the ground) from SnowModel output. sub_p.nc: NetCDF file of annual sublimation:P (total snow sublimation to winter P ratio; m/m) from SnowModel output. sum_P_may.nc: NetCDF file of annual cumulative winter P (mm) from SnowModel output. sum_snow_RO.nc: NetCDF file of annual total snowmelt (surface-water input into the soil that occurs when SWE > 0; mm) from SnowModel output. sum_sub.nc: NetCDF file of annual sublimation (total snow sublimation including surface, canopy, and blowing snow components; mm) from SnowModel output. swe_p.nc: NetCDF file of annual

This data release supports the study by Sexstone and others (2020) and contains simulation output from SnowModel (Liston and Elder, 2006), a well-validated process-based snow modeling system. Simulations are for water years 1984 through 2017 (October 1, 1983 through September 30, 2017) across a 11,200 square kilometer model domain in the San Juan Mountains of southwestern Colorado, United States that encompasses the Rio Grande Basin headwaters (HUC8 13010001). This data release also contains supporting field-based snow and meteorological station observations collected within the model domain during water years 2016 and 2017 that were used to evaluate SnowModel simulations. Sexstone and others (2020) provide details and summarize findings from the SnowModel simulations and supporting observations. SnowModel simulation output provided in this data release are stored in NetCDF files that have spatial (100-meter [m] grid resolution) and temporal (yearly) dimensions. Simulated SnowModel annual snow metrics (water years 1984 through 2017) in the attached NetCDF files include: mean winter (1 October to 31 May) air temperature (T; degrees Celsius [°C]), cumulative winter precipitation (P; millimeters [mm]), peak snow water equivalent (SWE; mm), SWE:P (ratio of peak SWE to winter P; m/m), snow-covered days (days with snow on the ground; days), total snowmelt (surface-water input into the soil that occurs when SWE greater than [>] 0; mm), snowmelt rate (rate the snow melts from peak SWE to melt out; millimeter per day [mm/day]), SM50 (water year day following peak SWE when half of snowpack has melted), peak SWE timing (water year day when peak SWE occurs), melt-out timing (water year day when snow melt out occurs), sublimation (total snow sublimation including surface, canopy, and blowing snow components; mm), sublimation:P (total snow sublimation to winter P ratio; m/m), 1 March SWE (mm), 1 April SWE (mm), 1 May SWE (mm), and 1 June SWE (mm). Supporting observations are provided in this data release in comma separated value (csv) files. Supporting meteorological station observations from three meteorological stations (daily mean values for the previous day) include: air temperature (°C), relative humidity (percent [%]), wind speed (meter per second [m/s]), incoming shortwave radiation (watts per meter squared [W m-2]), net radiation (W m-2), and albedo. Supporting field-based snow observations collected at 73 locations at a daily temporal dimension include: SWE (mm), standard deviation of SWE (mm), snow depth (m), and standard deviation of snow depth (m). An inventory and description of each of the files attached to the data release is provided below. Inventory of data release: URGB_SnowModel_study.xml: FGDC-compliant metadata file for the data release files. melt_doy.nc: NetCDF file of annual melt-out timing (water year day when snow melt out occurs) from SnowModel output . melt_rate.nc: NetCDF file of annual snowmelt rate (rate the snow melts from peak SWE to melt out; mm/day) from SnowModel output. peak_swe.nc: NetCDF file of annual peak SWE (mm) from SnowModel output. peak_swe_doy.nc: NetCDF file of annual peak SWE timing (water year day when peak SWE occurs) from SnowModel output. SM50.nc: NetCDF file of annual SM50 (water year day following peak SWE when half of snowpack has melted) from SnowModel output. snow_days.nc: NetCDF file of annual snow-covered days (days with snow on the ground) from SnowModel output. sub_p.nc: NetCDF file of annual sublimation:P (total snow sublimation to winter P ratio; m/m) from SnowModel output. sum_P_may.nc: NetCDF file of annual cumulative winter P (mm) from SnowModel output. sum_snow_RO.nc: NetCDF file of annual total snowmelt (surface-water input into the soil that occurs when SWE > 0; mm) from SnowModel output. sum_sub.nc: NetCDF file of annual sublimation (total snow sublimation including surface, canopy, and blowing snow components; mm) from SnowModel output. swe_p.nc: NetCDF file of annual

This data release supports the study by Sexstone and others (2020) and contains simulation output from SnowModel (Liston and Elder, 2006), a well-validated process-based snow modeling system. Simulations are for water years 1984 through 2017 (October 1, 1983 through September 30, 2017) across a 11,200 square kilometer model domain in the San Juan Mountains of southwestern Colorado, United States that encompasses the Rio Grande Basin headwaters (HUC8 13010001). This data release also contains supporting field-based snow and meteorological station observations collected within the model domain during water years 2016 and 2017 that were used to evaluate SnowModel simulations. Sexstone and others (2020) provide details and summarize findings from the SnowModel simulations and supporting observations. SnowModel simulation output provided in this data release are stored in NetCDF files that have spatial (100-meter [m] grid resolution) and temporal (yearly) dimensions. Simulated SnowModel annual snow metrics (water years 1984 through 2017) in the attached NetCDF files include: mean winter (1 October to 31 May) air temperature (T; degrees Celsius [°C]), cumulative winter precipitation (P; millimeters [mm]), peak snow water equivalent (SWE; mm), SWE:P (ratio of peak SWE to winter P; m/m), snow-covered days (days with snow on the ground; days), total snowmelt (surface-water input into the soil that occurs when SWE greater than [>] 0; mm), snowmelt rate (rate the snow melts from peak SWE to melt out; millimeter per day [mm/day]), SM50 (water year day following peak SWE when half of snowpack has melted), peak SWE timing (water year day when peak SWE occurs), melt-out timing (water year day when snow melt out occurs), sublimation (total snow sublimation including surface, canopy, and blowing snow components; mm), sublimation:P (total snow sublimation to winter P ratio; m/m), 1 March SWE (mm), 1 April SWE (mm), 1 May SWE (mm), and 1 June SWE (mm). Supporting observations are provided in this data release in comma separated value (csv) files. Supporting meteorological station observations from three meteorological stations (daily mean values for the previous day) include: air temperature (°C), relative humidity (percent [%]), wind speed (meter per second [m/s]), incoming shortwave radiation (watts per meter squared [W m-2]), net radiation (W m-2), and albedo. Supporting field-based snow observations collected at 73 locations at a daily temporal dimension include: SWE (mm), standard deviation of SWE (mm), snow depth (m), and standard deviation of snow depth (m). An inventory and description of each of the files attached to the data release is provided below. Inventory of data release: URGB_SnowModel_study.xml: FGDC-compliant metadata file for the data release files. melt_doy.nc: NetCDF file of annual melt-out timing (water year day when snow melt out occurs) from SnowModel output . melt_rate.nc: NetCDF file of annual snowmelt rate (rate the snow melts from peak SWE to melt out; mm/day) from SnowModel output. peak_swe.nc: NetCDF file of annual peak SWE (mm) from SnowModel output. peak_swe_doy.nc: NetCDF file of annual peak SWE timing (water year day when peak SWE occurs) from SnowModel output. SM50.nc: NetCDF file of annual SM50 (water year day following peak SWE when half of snowpack has melted) from SnowModel output. snow_days.nc: NetCDF file of annual snow-covered days (days with snow on the ground) from SnowModel output. sub_p.nc: NetCDF file of annual sublimation:P (total snow sublimation to winter P ratio; m/m) from SnowModel output. sum_P_may.nc: NetCDF file of annual cumulative winter P (mm) from SnowModel output. sum_snow_RO.nc: NetCDF file of annual total snowmelt (surface-water input into the soil that occurs when SWE > 0; mm) from SnowModel output. sum_sub.nc: NetCDF file of annual sublimation (total snow sublimation including surface, canopy, and blowing snow components; mm) from SnowModel output. swe_p.nc: NetCDF file of annual

This data release contains SnowModel snow evolution simulation output on a 100-meter (m) geospatial grid for a 311 kilometer (km) × 300 km model domain in Colorado, United States, encompassing the Colorado and Gunnison River Basin headwaters in the Upper Colorado River Basin. Weather Research and Forecasting (WRF) Model convection-permitting and orography-resolving (4-km grid spacing) regional climate simulations provided the atmospheric forcing conditions to drive SnowModel in both a current and future climate scenario. A pair of continuous 13-water-year (2001-13) WRF model simulations was utilized: (1) a current climate control (CTL) simulation forced using ERA-Interim reanalysis, and (2) a future climate simulation using the pseudo-global-warming (PGW) method that uses the ERA-Interim reanalysis for the same period as (1) and adds an ensemble mean climate delta from 100 years in the future for the most extreme Representative Concentration Pathway (RCP) 8.5 scenario. The six SnowModel simulated outputs provided separately as child items in this data release include (1) air temperature (tair), (2) precipitation (prec), (3) precipitation amount falling as snow (spre), (4) snow water equivalent (swed), (5) liquid water supplied to the soil-snow interface from snowmelt (smlt), and (6) liquid water supplied to the soil-snow or soil-air interface either from snowmelt or rainfall (roff). The simulations used to produce these outputs were conducted on a 100-m geospatial grid. Land cover information (file vege.asc) for the simulation was provided by the 2010 North American Land Change Monitoring System and elevation information (file topo.asc) was provided by the U.S. Geological Survey National Elevation Dataset.