Due to a change in the HMS development cycle, more than one version of HMS has been made available to users since CWMS 3.2.1 was released. Since the 3.x CAVI was designed to accommodate the replacement of the individual model plugins with newer versions, instructions were provided to enable users to upgrade the version of HMS that they used in CWMS 3.2.1.  Therefore, it is important to know which version of HMS you are currently working with in CWMS 3.2.1 so that you can ignore those instructions that do not pertain to you and your watersheds. To identify the version of HMS you are using, simply launch HMS from the CAVI or from the HEC-HMS folder in the CWMS installation folder, then check the HMS title bar - the version number is displayed right after the program name.

  1. Hidden dialog(s) -  please see details in "HEC-HMS Best Practices in CWMS"
    1. On the initial start up of a new CWMS watershed, there may be one or more hidden popup dialogs that are keeping you from proceeding with CWMS (sometimes looks like CWMS is frozen and unresponsive).  Sometimes the application will be flashing on task bar but sometimes nothing may be shown.  When this occurs, you can use the "windows key" + "m" and it should minimize all windows except for the window wanting attention.  Additionally, "alt" +"TAB"  or "windows key" + "TAB" will allow you to see what is open and if there is an HMS tab when HMS was not previously open, it is probably a prompt related to CWMS. 
    2. Most of the time, this prompt will be about pointing to a forecast.dss file.  This needs to be filled in with the forecast.dss file, and usually the prompt window gives the user the rough location of where the forecast.dss file is located.   This is usually due to an absolute path stored within the HMS model that references a location external to the HMS model folder.  To help alleviate this issue in the future,  make sure all HMS data is stored internally to the HMS file directory. 
    3. For models with extensive DSS path issues, and modelers with significant HMS expertise, see "HEC-HMS Advanced - Managing References".
  2. If you are having visual issues with HMS, please check out this discourse post about how to correct some visual issues by changing properties.
  3. There are also some additional know issues that the HMS team documented on the website here.
  4. CWMS 3.2.2 comes with HEC-HMS 4.8 but when newer versions of HEC-HMS are created, it is suggested to update the HMS versioning in the CWMS/HEC-RTS build.  The user can update the HMS by replacing the contents of the HEC-HMS folder with the newer version of HMS.  No other modifications are needed at this time to upgrade HEC-HMS versioning.
  5. Having multiple routing methods can cause zonal modifications such as combined parameter editor not work as expected.
    1. Mod Puls routing recommended where you have RAS models that can generate storage-outflow relationships
    2. Muskingum-Cunge (8 point cross-section) is recommended elsewhere.
  6. HMS 4.2.1 upgrade to HMS 4.3 or newer: HMS basin models that use Muskingum-Cunge or Kinematic Wave routing will need to have either index flow or index celerity added to each reach element.
    1. Suggestion: Use index celerity of 5 ft/s
  7. Observed stage data is overwriting observed flow data. Therefore, while using HMS 4.8, please use only observed flow. This should be fixed in HMS 4.9.
    1. If you use observed stage, note that it will be saved in the DSS file as a path denoting it as observed flow and not stage. This only appears to be an issue with HMS 4.8.
  8. Periodically, HMS will not show the compute when running with HEC-MetVue. The compute will complete and then all the dialog will populate in the compute window at once. All seems to work fine, just a visual issue and only seems to be present when running in conjuncture with MetVue.
  9. HMS Error 16160 (see below) will generate in specific cases. This "error" is not impacting and is fixed in HMS 4.9.