Forecasts

A forecast is a time window associated with one or more forecast runs.

Creating a Forecast

The following are the steps for creating a new forecast: 

1. From the CWMS CAVI main window, click the Modeling tab. Select New from the Forecast menu, and the Create New Forecast dialog will open.
   
2. By default, New Forecast is the default selection in the Select Type drop-down list. The options are:
   1. New Forecast - the default option, allows you to create a new forecast
   2. From Existing Forecast - copies the Time Window settings and selected Forecast Run(s) from a forecast that has already been created
   3. From Archived Forecast - copies the Time Window settings and selected Forecast Run(s) from an archived forecast (for more information on archiving your forecast see Managing Forecast Data)
   4. From Imported Forecast - copies the Time Window settings and selected Forecast Run(s) from a forecast file stored to disk.
3. Enter a forecast date and time in the Time Window fields. The default Forecast Time is the current date and time.
   1. You should determined the forecast time using the Acquisition module. This should be the latest time a complete set of reliable data is available.
4. Once you edit the Time Window settings, CWMS generates a forecast name and creates a folder based on the forecast date and time. The Folder box contains the generated pathname and file for the forecast.
   1. You may choose to edit the default name of the forecast if desired.      
5. The selected Start Time and Extract Start dates should be far enough in the past to meet the following criteria:
   1. Allow enough timesteps 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. The Start Time and the Extract Start dates should provide enough time to calibrate loss rates in 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 times 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).
6. The Extract Start, Start Time, and End Time fields will default to dates based on the Default Time Window settings. These options can be changed by accessing the Default Time Window option from the Forecast menu of the Modeling module.
   
7. From the Create New Forecast dialog, you can override the default time window by adjusting the dates and times as needed for your forecast.
8. Select the pre-defined forecast run(s) you wish to include in the forecast from the list at the bottom of the dialog. Clicking the check box in the Selected column of the table will select the forecast run. You can select multiple forecast runs if necessary.
   
9. Click OK, and the Create New Forecast dialog will close. A Progress window will open, which provides information on the creation of the forecast.
   
10. In addition, CWMS extracts data from various data sources (CWMS Data API, Cumulus, HEC-DSS, WISKI, and the CWMS database) based on the time window and specifications made to the Extract Editor. The data is copied to an HEC-DSS file (forecast.dss) for use by the models. Check the Extract Results log for any issues that might have occurred during the extract process.
11. The Modeling tab will display the created forecast (with a forecast run selected) in the Map Window. In addition, the name of the forecast, time window information about the forecast, and forecast run(s) information are displayed.