# Presentation: 424071

## Robert Rozumalski 
National SOO Science and Training Resource CoordinatorNOAA/NWS/OCWWS/Training Division/FDTB

- National SOO Science and Training Resource CoordinatorNOAA/NWS/OCWWS/Training Division/FDTB

- Real-time forecasting with WRF EMS

- SOO/STRC WRF Environmental Modeling System

## Real-time forecasting

- Provides easy access to initialization data sets
- Data fail-over mechanisms integrated into the system
- Knows current date to use for model initialization
- Internal “stand-by” mode while waiting for initialization data to appear on remote server or a previous run to finish

## Real-time forecasting

- Allows for the processing of forecast files while model is running
- Multiple forecast data formats supported
- Facilitates the process of getting model forecast files to forecasters

- The WRF EMS Cont’d

## Real-time forecasting

- Designed to execute the WRF EMS run-time scripts in a controlled process
- Executes wrf_prep.pl, wrf_run.pl, and wrf_post.pl in succession
- Provides flexibility when setting up a real-time run
- Notifies user(s) if there is a problem

- Real-time forecasting process is managed by the wrf_autorun.pl routine

## Real-time forecasting

- Located in the conf/wrf_autorun directory
- Specifies the data set(s) to use for model initialization and any alternatives should the primary data set not be available
- Specifies any special land surface and static surface data sets such as SST
- Identifies the method of data acquisition, preferred data server, and any fail-over methods and locations
- Establishes the default length of the real-time forecasts

## Real-time forecasting

- Contains the configuration for any nested domain
- Specifies the mechanism for data post processing
- Identifies the user to email if there are problems
- Determines the amount of time to wait for data on another server or for a previous run to finish

## Real-time forecasting

- Checks to see if a previous run is still on the system, if true then waits for the run to complete
- Runs wrf_prep.pl – notifies user and exits upon failure
- Runs wrf_run.pl – notifies user and exits upon failure
- Runs wrf_post.pl – notifies user upon failure

## Real-time forecasting

- % wrf_autorun --help
- Displays the various command-line options and flags available
- % wrf_autorun --guide
- Displays much more detailed information of the user options

## Real-time forecasting

- % wrf_autorun
- Uses all the default values previously defined in the wrf_autorun.conf and other configuration files
- % wrf_autorun –dset gfs%gfsgrb2
- Overrides the default data set specified in the configuration file

## Real-time forecasting

- % wrf_autorun  --nests 2,4  --autopost
- Overrides default settings by initializing and running nested domains 2 and 4. Also starts synchronous post processing of the forecast files
- % wrf_autorun --cycle 12:06 --length 24  --date 20040231 Overrides the default values for simulation start date, cycle, initialization hour, and length

## Real-time forecasting

- Located in the wrf/strc directory
- A wrapper file for executing wrf_autorun.pl via cron
- Used to set the necessary WRF EMS environment variables
- Accepts the same flags and options as wrf_autorun.pl
- Deactivated entry placed in WRF user’s crontab file during installation
- May be run from the command line

- Use wrf_autorun-wrapper.csh when running in real time!

## Real-time forecasting

- Do not use the --cycle or --date flags
- 	The WRF EMS knows the current date and cycle time for the initialization data set requested
- Start your forecast after the initialization files are on remote server
- 	The WRF EMS anticipates the amount of time required to run the model and process the forecast files used for initialization of your run. Starting a real-time run before the expected time of data availability will result in your run using an older data set.

## Real-time forecasting

- Expedite the forecast by using a non-initial hour forecast from your initialization data set as your zero-hour forecast
- 	For example, use a 06 hour forecast from the 06 UTC run of the GFS as your 12 UTC, 00-hour forecast. This step provides you with a 6-hour head start in getting forecasts to forecasters!
- Find unused workstation for synchronous post processing of forecast files
- 	Forecasters can make use of the early forecast hours
- Follow the general guidance for configuring a model forecast
- 	Don’t let boundary condition influences contaminate your forecasts
- 	2-way nesting ameliorates the BC issues

## SOO/STRC WRF Environmental Modeling System

- Real-time forecasting with WRF EMS

- SOO/STRC WRF Environmental Modeling System