1.1 Acquire meteorological gridded data from the National Blend of Models (NBM) source

Similar to a standard HEC-RTS workflow, this step requires acquiring time-series datasets for observed streamflow, reservoir operations, and meteorological inputs from multiple sources including USGS, CDEC, NOAA, and USACE.

The gridded meteorological dataset used in this tutorial was pulled from the NBM dataset generated by NOAA. Additional information on NBM data generation and methodology is available on NOAA’s website. The gridded precipitation datasets were obtained through the Cumulus data service (see here). You do not need access to Cumulus to run the workshop, the data has already been imbedded into the workshop files. 

Data acquisition and extraction follow the standard procedures described in existing CWMS tutorials and workshop materials; therefore, those steps are not repeated here. (e.g., check this link).

1.2 Acquire ensemble forecast streamflow data

Users can download forecasted ensemble streamflow data for any watershed within the CNFRC locations using an ensemble script available under the HEC-RTS Tools and Script Editor. The script used in this case, ESP_Import_Russian, downloads data for each streamgage of interest over a specified time period, processes the data, stores ensemble time series in DSS files, and handles cases where data for a gage are unavailable. The script is editable and adaptable for any watershed where RFC ensemble datasets are available.

The steps in this task are the same as those presented in the referenced tutorial (see link) and are presented here for completeness. You do not need to follow these steps on your computer, the data has already been gathered for the workshop.

  1. Make sure that the Ensemble Data Acquisition Script (e.g., a file named ESP_Import_russain.py in this case) is available in the Scripts Editor. If it is unavailable, find the script file and add it to the Script Editor. For information on how to Set up a Script in CAVI, check related resources, such as Set Up a Plot Script in the CWMS workshop here. 

2. Update the script to include the stream gages of interest for the watershed. The streamgage name specified in River Forecasting Center's source must match the names used in the Script (see line 41:51 of the Script Editor). The script will generate an error if a streamgage name is incorrect or if no data are available for that streamgage.

The figure below shows where the user should update the watershed name on line 39 and specify the gages from which they want to pull data under the variable name GagesOfInterest. Information on watershed and gage codes is available from CNRFC sources. 

It should also be noted that the current scripts pull the latest ensemble records available on the CNRFC source. If you are trying to replicate this tutorial, please use the ensemble dataset included in the database folder (CNRFC_ensembles.dss).


After updating the script, run it. A message will pop up when data collection is complete (see figure below), confirming that the Save/Run operation finished without errors. Upon successful completion, all ensemble datasets are stored in the designated database folder with the specified file name (e.g.,  CNRFC_ensemble.dss in this case).

3. Verify that ensemble data are available by selecting “Condensed – Group Collection” from the “View” menu and plotting the data in DSSVue as shown in the figure below.