Once you've set up your ensemble forecast run, configured the necessary extract group(s), and verified all model linkages, you're ready to generate and compute an Ensemble Forecast.

This guide walks you through the process of creating and executing an ensemble forecast in your HEC-RTS watershed.

Step 1: Create New Forecast

  1. Launch HEC-RTS and open your watershed.
  2. Navigate to the Modeling tab.
  3. From the Forecast menu, select New.
  4. In the Create New Forecast dialog:
    1. Set the appropriate Time Window (start and end dates/times).
    2. Select your ensemble forecast run from the list.
  5. Click OK to create the forecast.

The new forecast will load in the Modeling tab, and the extract process will begin automatically.

Modeling Tab - New Ensemble Forecast Run

Ensemble forecast runs appear italicized in the interface, helping you distinguish them from deterministic runs.

Step 2: Review Input Data

  1. If the extract list that contains the collection data does not automatically run:
    1. From the Forecast menu, select Extract.
    2. Uncheck any preselected groups.
    3. Check the box for your ensemble extract group and click Run Now.
  2. Right-click the forecast run in the Forecast Run Tree and select Forecast DSS file.
  3. Review the contents of the forecast.dss file to ensure that all expected ensemble member records were extracted successfully.

CWMS-Vue - forecast.dss File with Ensemble Collections

Step 3: (Optional) Select Specific Traces to Compute

You can choose to compute all traces or just a subset of them. If you wish to run all traces, skip this step.

To select specific traces:

  1. Select your ensemble forecast run in the Forecast Run Tree.
  2. Go to the Actions tab and click Select Traces to Compute.
  3. In the Select Trace to Compute dialog:
    1. Enter the trace number(s) in the Ensemble Member field. Only traces defined in the Forecast Run Editor are valid selections.
    2. Use commas and dashes to define your selections (e.g, 1,3,5-8). Clicking the ellipsis will open a larger text window to enter your selection. 
    3. Leave the field blank to compute all traces.
  4. Click OK to close the dialog.

Select Trace to Compute Dialog

Step 4: Compute the Ensemble Forecast

  1. With the ensemble forecast run selected, go to the Actions tab.
  2. Click Compute to run the ensemble forecast.

Final Review

Your ensemble forecast will now execute using the selected traces and input data. Once the compute is complete, you can proceed with analysis and visualization using the HEC-RTS tools.