Task 2: Alternative Keys and Forecast Runs

In this task, you will begin assembling the individual models into Forecast Runs, which is part of the blueprint for creating a forecast. First, you will set the Alternative Keys that are used to identify model alternatives in the forecast model sequence. These keys are used to form HEC-DSS F-parts that allow the CAVI and the user to recognize which model outputs belong to which model alternatives.

 Assign Model Alternative Keys

1. From the Setup tab, open the Model Alternative Keys dialog by selecting Models>Model Alternative Keys.
2. Selecting a model from the Plugin drop-down menu at the top of the window, and fill in the boxes in the left column of the table. Each model key is a single letter or number. 
3. Follow the examples below when assigning keys to the model alternatives.
   
   
   
4. Click Apply, then OK to exit the browser.

Build Forecast Runs

Now you can build Forecast Runs by selecting combinations of model alternatives to run in sequence.

1. From the Models menu, select Forecast Runs… to open the Forecast Run Editor.
2. Click the New Run button.
3. Enter No Future Precipitation in the Name field and Rain on the ground only in the Description field.
4. Select the models alternatives that will be a part of the Forecast Run
   1. No_QPF for HEC-MetVue
   2. Daily Forecasting - 1HR for HEC-HMS
   3. RT Normal for HEC-ResSim
5. Save the Forecast Run by clicking Apply.
6. Your editor should look like this when complete:
   
7. Create a second forecast run called Future Precipitation. It should be the same as the No Future Precipitation run, but it should use the other HEC-MetVue alternative (QPF).
   
8. Click OK to exit the Forecast Run Editor and Save the watershed.

Why would you want to have Forecast Runs that use different HEC-MetVue alternatives, but the same alternatives for the HEC-HMS and HEC-ResSim models?