Data and tools

Overview

This section of the Colorado River Science Wiki automatically collates all of the information found under the Data and tools headings on every page in the Science and applications section, and lists it below in the same order as the the pages in the Science and applications section.

Paleohydrology

TreeFlow

The TreeFlow resource provides access to data, metadata, and plots of nearly all existing tree-ring reconstructions of streamflow for the Colorado River Basin, as well as other river basins throughout the U.S. Currently there are 31 gages in the Upper Basin and 4 gages in the Lower Basin for which reconstructions are available.

• Meko et al. 2007 reconstruction of Lees Ferry gage (762-2005)

PaleoFlow

The Paleoflow tool provides additional analysis and plotting options for the Colorado River Basin reconstructions that are available on TreeFlow, including dynamic time-series plots, analysis of extreme events, and comparisons of distributions (probability density functions) between two periods. Make sure Time Resolution = Annual to see the full list of reconstructions.

Seasonal streamflow forecasts

CBRFC

CBRFC has multiple ways to access and view their seasonal water supply forecasts and related data:

CBRFC Conditions Map - Water Supply Forecasts

CBRFC Conditions Map - Water Supply Forecasts

The Conditions Map can display several different types of hydroclimate information, depending on the tab selected. The Water Supply Forecasts tab, when opened, defaults to the most probable (50% exceedance) values for the official 1st of month forecasts, but can also display the latest daily ESP forecasts ("Latest Model Guidance"). Clicking on the triangles (forecast points) brings up a thumbnail forecast evolution plot for that point; clicking within the plot opens a page specific to that forecast point, with an interactive forecast evolution plot and links to plots for previous years, calibration and validation data, and historical streamflow volumes for that point.

CBRFC Upper Colorado Situational Awareness

This page shows the most recent official forecasts for Lake Powell inflows (~all Upper Basin runoff) for April-July and the water year; maps of observed/modeled soil moisture, snowpack, and precipitation used to inform the forecasts; and graphs showing how the sub-basins' contributions and overall forecasted volume compares with average conditions.

CBRFC Water Supply Official Forecast List

This page features an interactive table with the official 1st of month forecasts for all forecast points. Like the forecast map, it links to the pages for each point.

CBRFC Water Supply Forecast Discussion

This document (PDF) discusses provides a general overview of the official (1st and 15th of month) CBRFC forecasts, describing the weather/watershed conditions that have led to the forecasts, as well as forecasts and outlooks for upcoming weather.

CBRFC Water Supply Webinars

From January through May, CRBFC presents one-hour webinars around the 7th of the month to explain the latest streamflow forecasts, the weather and snow conditions leading up to the forecasts, and the weather conditions forecasted for the next two weeks. Scroll down to "Presentations 20xx" for a link to the webinar archive for the current year; and then find the Water Supply Webinar" of interest. Both the slides and a recorded video with slides are available.

NRCS

NRCS likewise has several ways to access and view their seasonal water supply forecasts and related data.

NRCS Interactive Map - Forecasted Streamflow Volumes

NRCS Interactive Map

The NRCS Interactive Map is a versatile tool to access and view all NRCS hydroclimate data, including the seasonal water supply forecasts. The link above has been specifically set up to show the most probable (50% exceedance) values for the current seasonal water supply forecasts, for individual points, but users can select other ways to visualize the forecast data, e.g., by basin, as percentiles, or for different forecast periods. Similar to the CBRFC Conditions Map, clicking on an individual forecast point will bring up a small window with the name of the point and forecasted streamflow volume; clicking on that window will bring up other options for viewing additional data for that point, including other statistics for the forecasted streamflow, and the observed streamflows for the water year.

NRCS Water Supply Forecast Chart

The Water Supply Forecast Chart shows the potential range for the forecasted streamflows (90%-70%-50%-30%-10% exceedances), similar to the shaded bands on the CBRFC forecast evolution plots. Note that the sub-basins within the CRB are shown by state; forecasts for Colorado R at Glen Canyon Dam (i.e., Lake Powell inflows) are accessed under Utah >Southwestern Utah.

NRCS State Basin Outlook Reports

The Basin Outlook Reports (also known as Water Supply Outlook Reports in some states) are issued monthly or semi-monthly from January through June by the state-level NRCS Snow Survey Offices, and supplement the NRCS seasonal water supply forecasts with narratives of statewide precipitation, snowpack, and water supply conditions, and additional graphics showing the water supply forecasts by sub-basin, alongside snowpack, precipitation, and reservoir conditions.

• Arizona (issued Jan-Apr)
• Colorado
• New Mexico
• Utah
• Wyoming

ASO-informed forecasts for Colorado and Utah (CBRFC)

In collaboration with the Colorado Airborne Snow Measurements (CASM) program, the Colorado River Authority of Utah, and the Central Utah Water Conservancy District, CBRFC is producing experimental seasonal water-supply forecasts for ~20 gages in Colorado and Utah. In these forecasts--which can supplement, but do not replace, CBRFC's official forecasts for the same gages--SWE estimates from the Airborne Snow Observatories (ASO) lidar system are directly inserted into CBRFC's SNOW-17 snowpack model. In 2024, the experimental CBRFC forecasts were produced 2-3 times at each gage between late March and early June. (The 2021-23 forecasts for Colorado gages can be obtained through the embedded table in this page at CASM.) CBRFC has committed to producing the ASO-informed experimental forecasts in spring 2025.

ASO-WRF-Hydro forecasts for Colorado and Utah (ASO)

Airborne Snow Observatories (ASO) also produces its own streamflow forecasts for many of the basins across the West in which it conducts flights to generate lidar-based SWE estimates. These forecasts use the WRF-Hydro hydrologic model to translate from SWE and other parameters into runoff. Typically 1-3 forecasts for each gage are produced during the spring runoff season. Free registration is required to view the ASO forecasts.

Woodson Lees Ferry WY flow forecast

This forecast procedure was developed by David Woodson as a part of his PhD research at the University of Colorado Boulder. The forecast uses a machine learning (random forest) model trained on Reclamation annual natural flow for the Colorado River at Lees Ferry, AZ for water years 1921-2023 as the predictand, and predictors including the Pacific Decadal Oscillation (PDO), the Atlantic Multidecadal Oscillation (AMO), and 12-month forecasts of precipitation and temperature from a climate model.

Utah Climate Center - Multi-Year Forecasts of Colorado River Water Supply

These forecasts differ from the other ones listed above in having a much longer outlook period: 1-3 years. These forecasts leverage research that has identified "long-term ocean memory": Anomalies of sea-surface temperatures (SSTs) in the North Pacific and tropical Atlantic, up to 44 months prior to the forecasted year, that impart predictability of Upper Basin streamflow (natural flow at Lees Ferry).

24-Month Study Model (24MS)

24-Month Study Reports

The output of the primary monthly run of the 24-Month Study Model (using most probable inflows) is released around the 15th of each month. These results are formatted by Reclamation as a standardized set of data tables totaling 17 pages. The Upper Colorado and Lower Colorado regional offices package this set of data tables differently; Upper Colorado adds a 9-page narrative summary for the Upper Colorado reservoirs, while Lower Colorado adds a single cover page with very a brief summary. Note that both report "flavors" contain the results for both Upper Basin and Lower Basin reservoirs.

24-Month Study Reports - as distributed by Upper Colorado Region

24-Month Study Reports - as distributed by Lower Colorado Region

Supplemental 24-Month Study runs

As noted above, two supplemental runs of 24MS are performed either 4 times per year, or monthly, depending on projected reservoir conditions. These runs, based on probable minimum and probable maximum inflows, bracket the uncertainty in the primary run.

Probable Min/Probable Max runs