Forecasts

A forecast is a time window, that is associated with one or more forecast runs. Following are the steps for creating a forecast: 

1. From the CWMS CAVI main window, click the Modeling tab, from the Forecast menu, click New. The Create New Forecast dialog (Figure 1) will open.
   
2. By default, from the Select Type list (Figure 1) you are creating a new forecast (New Forecast). From the list you have the following options:
   1. New Forecast. This is the default option in which you specify the Forecast Time, Extract Start, Start Time, End Time and Forecast Run(s) used in the forecast.From Existing Forecast. This option copies the Forecast Time, Extract Start, Start Time, End Time and Forecast Run(s) from a forecast already created. Here you select a forecast already created and saved in the watershed.
   2. From Archived Forecast. This option copies the Forecast Time, Extract Start, Start Time, End Time and Forecast Run(s) from a forecast that has been archived. Here you select the zip file containing the archived forecast. For more information on archiving your forecast see Managing Forecast Data.
   3. From Imported Forecast. This option copies the Forecast Time, Extract Start, Start Time, End Time and Forecast Run(s) from a forecast file stored to disk. Here you specify the *.forecast file to use.
3. By default, CWMS creates a forecast name, based on the time window (Figure 1). By default, CWMS creates a time window based on the current date and time; for examples in this user's manual, the time window is an historical event.
4. You will enter a forecast date and time that you determined in the Acquisition module, this would be the latest time a complete set of reliable data is available (Figure 2). For example, in Figure 2, a Forecast Date of 26Jan2017 has been entered along with a Forecast Time of 2000.
5. Once the Forecast Date/Time has been entered, CWMS creates a forecast name. As illustrated by Figure 2, in the Name box, by default, the forecast name of 2017.01.26-2000 has been generated. Also, by default, CWMS creates a folder based on the forecast date and time. As illustrated in Figure 2, the Folder box contains the generated pathname and file for the forecast name – C:/CWMS/Forecast/2017.01.26-2000/WS10_HEC_RussianRiver. WS10 HEC_RussianRiver_ is the name of the watershed. The Folder box (Figure 2) is non-editable.
6. The selected Start Time and Extract Start dates (Figure 2) should be far enough in the past to meet the following:
   1. Allow enough time steps to pass between the Start Time date and the Forecast Time date to allow routing reaches in the reservoir model to show correct flows at the time of forecast.
   2. Generally, the Start Time and the Extract Start dates should be before the start of the event for calibration of loss rates for HEC- HMS. If this is not practical, then a time after the initial losses have been satisfied should be chosen. In most cases these dates and time are equal. However, from time to time, the forecaster may wish to extract data prior to the simulation window or may wish to update only the last few hours of data (for example when re-computing a forecast later in the day after more observed data are available).
7. The Extract Start, Start Time and End Time fields will default to dates based on information given in the Default Time Window dialog (Figure 3). To view this information from the Forecast menu, click Default Time Window, the Default Time Window dialog will open (Figure 3).
8. From the Create New Forecast dialog (Figure 2) you can override the default time window. You will also need to enter times for the corresponding dates.
   
9. From the Forecast Runs table (Figure 4) on the Create New Forecast dialog (Figure 2) select the already defined forecast runs you wish to simulate for the forecast. Clicking the check box in the Selected column of the table selects a forecast run. You can select multiple forecast runs.
   
10. Click OK, and the Create New Forecast dialog closes (Figure 2). A Progress window will open (Figure 5), which provides information on the creation of the forecast, its associated directory, and the copying of the appropriate files to that directory.
    
11. In addition, CWMS retrieves (extracts) data from the CWMS database based on the entered times. The data is copied to a DSS file (forecast.dss) for use by the models. Check the extract results log (Viewing Results) for any issues that might have occurred.
12. The Modeling tab ( Figure 6) will display the created forecast (with a forecast run selected) in the Map Window (Figure 6). In addition, the name of the forecast; time window information about the forecast; and forecast run(s) information are displayed.