Snow Survey Program Information

• We monitor data from SNOTEL sites regularly and generally catch site issues within several days. However, it may take several weeks for us to fix site issues depending on season, weather, and ease of site access. You may monitor this link for an up-to-date list of SNOTEL data issues. We do appreciate correspondence from the public when there are issues with site data however, as this helps inform us on who is using the data and urgency of the site repair. Commonly, issues with SNOTEL site data are related to malfunctioning telemetry equipment. In these instances, data is still collected at the SNOTEL site and will be backfilled to the server once we can visit the site for repair. Every effort will be made to address data outages and the prompt restoration of the data to our website. If you have further questions, please contact us at the following email address: co-nrcs-snow@one.usd.gov.

• SNOTEL data can be accessed via API using the AWDB Web Service. This link contains a tutorial to help users get started using the AWDB Web Service.

How do I download historical data for a specific SNOTEL site or group of sites?

Historical data for a specific SNOTEL site can viewed and download in two primary ways: the National Water and Climate Center's Report Generator Tool or the Interactive Map.

• For tabular data, the Report Generator Tool allows you to download any/all data from individual or groups of SNOTEL sites. Modify the reports by clicking the “Create/Modify Report” button on the upper left-hand corner of the window. From this tab you can adjust the report parameters such as the location, date, and format of the report. You can also produce the data as a graph instead of a table. You can download the data as a CSV file by selecting CSV under the "Output Format" menu. The data in can be viewed in either a chart or CSV form by adjusting the “Layout” or “Output Format” buttons. Each individual SNOTEL site data can be accessed as far back as the site has been active using this tool. The median or mean SWE for a site can also be downloaded with Report Generator.
   
  • For example, this report includes the snow depth and snow water equivalent data from all Colorado SNOTEL sites in the Rio Grande River basin watershed for the winters from 2010-2021.
     
  • As another example, this report includes snow depth, snow water equivalent, wind speed, wind direction, soil moisture, soil temperature, and observed air temperature from the Berthoud Pass SNOTEL site in Colorado for the current water year.
• Pre-defined tables and charts can be accessed through the Interactive Map by clicking on an individual SNOTEL site. On the far left of the screen, you have the option to download all basin data as a csv or by individual site. If you are primarily looking for visual snowpack information, the Interactive Map can be very helpful as you can toggle the date and view the status of the snowpack in a basin during different years and different times of winter.

How do I find historical snow course information and data?

• Snow course data is collected monthly to semi-monthly from January thru May depending on the individual snow course. This data can be accessed via the Interactive Map by selecting the Snow Course/Aerial Marker button under the USDA-NRCS Non-Real-Time Networks button from the menu on the righthand side of the page. This link shows the snow depth at each of the snow courses in Colorado for the end of January 2020.
• Snow course data may be downloaded via Report Generator. Here’s an example from the Boulder Falls snow course of the data you can get from Report Generator. If you would like to see what settings produced this report click on the Create/Modify Report tab in the top left corner. Note that you must select “Semi-Monthly” as the interval/duration to access snow course data.

How do I find data for a particular river basin?

• Data for an individual river basins can be found using the Interactive Map. This data source allows you to display both individual SNOTEL sites and basin summaries of snow, precipitation, and streamflow forecasts. You can also click on individual sites to access graphs for them, among many other ways to look at the data. The reports have access to all the most up-to-date and historically corrected data. Here is an example for the Colorado Headwaters River Basin.
• The Interactive Charts are also a good tool for comparing SWE and precipitation in different years. These are also available for individual sites through the Interactive Map.
• Using Report Generator, you can select data for all of the SNOTEL stations within a particular river basin. For example, this link is for SWE data from 2010 to July 2021 for all SNOTEL stations in the Upper Colorado river basin including some stations just outside of the basin that we use to represent SWE on the divides. The data can be downloaded the as a CSV file by selecting CSV under the "Output Format" menu. You can also modify the report by clicking the "Create/Modify Report" button in the upper left-hand corner.
• The Basin Data Report provides precipitation, snowpack, reservoir, and streamflow forecast data in a PDF format from January to June on a state-by-state basis.
• The Update Report is one that is generated once at the beginning of the month with data that is available at that time. The data is provisional and may come with data errors.
• Additionally, the April-July streamflow forecasts for Colorado within the Water Supply Outlook Report provide details about each individual river basin forecasts as well as the statewide streamflow summary.

Do you provide distributed snow water equivalent or snow depth map products?

• Unfortunately, we do not produce a distributive snow depth or snow water equivalent (SWE) model for Colorado. However, the Airborne Snow Observatories uses LiDAR to measure basin-wide snow depths (and estimate SWE) in certain regions of Colorado. In addition, several research groups currently produce distributed SWE models of Colorado, such as SNODAS which is produced by the National Oceanic and Atmospheric Administration, and SWANN which is produced by the University of Arizona.

Where do I find SNOTEL site coordinates?

• A tabular list of SNOTEL site coordinates in the WGS84 coordinate system (Latitude/Longitude) are available on from our Report Generator application. This list also provides site metadata including site elevation, county, HUC-8 river basin, and site installation date.

How do I find out which sensors are present at a SNOTEL site?

• Information on which sensors are present at a particular SNOTEL site can be found on the “Site Page”. These can be accessed via the Interactive Map Start by clicking on the site of interest to open the pop-up window, click on the “Data Reports” drop down menu, and select the “Site Page”. The “Site Reports” table will list the sensors currently deployed at each site.
• We do not typically perform any quality control or adjust values for the data from the extended sensors, such as wind speed and direction, relative humidity, soil moisture and temperature, and barometric pressure.

Do you provide data on land cover type and/or canopy cover at each SNOTEL site? Soil infiltration parameters?

• In Colorado, most SNOTEL sites are located within subalpine spruce and pine forests. We do not have a specific database for this type of information, but the geographic locations of SNOTEL sites can be obtained using our Report Generator Tool or Interactive Map. Using those locations, you can use the National Land Cover Database to determine the specific land cover type.
• We do not measure soil infiltration parameters (hydraulic conductivity, water retention parameters, etc.) at SNOTEL sites. However, the SCAN network typically has well documented soil hydraulic parameters.

Do you have river basin shapefiles available for download?

• We have basin data used by our map products available as GeoJSON files. These files contain very course polygons of the basins. For more accurate shapefiles see the second bullet. 
  • Colorado Snow Survey Custom Major Basins (non standard basins)
  • Colorado Snow Survey Custom Minor Basins (non standard basins)
  • Western US HUC2
  • Western US HUC4
  • Western US HUC6
  • Western US HUC8
• For research grade shapefiles, we recommend getting shapefiles from USGS or another source (for HUC 6, 8, or 10) and trimming to state boundaries. Most of our basin delineations are based off those interpretations, however, we attribute our in-house basin projections to specific SNOTEL stations.