Enter a ZIP code to get a forecast:
Setup Location

WRN Logo

Prompts and Menus

The ability to guide the user through the  rough task of selecting options is critical for most programs.  WXP employs a system of prompts and menus to guide the user to the final product. Even though the menu system can provide access to many types of plots, the command line and resource interface is far more powerful.  There is a balance between providing basic capabilities to the user through the menus and overwhelming the user with choices.

NOTE for Windows 95/98/NT Version -- In all graphics applications, there is no ability to print messages, prompts and menus to standard output.  For these applications, the menus and prompts are disabled.  As a result, all pertinant information must be specified on the command line.

Program Prompts

Many WXP programs prompt the user for information.  A prompt is used when the number of options is fairly limited and explanation is not required.  Each prompt is a request for a resource value.  In some cases, you will enter the exact value for the resource as in a filename.


   Enter the surface filename: 96112206

The filename is entered from the list of files.  You can abbreviate the value in some cases as in the above example.

In other cases, you will enter an abbreviation for the resource.

   Display (D) or Postscript (P):

The abbreviations will be clearly listed at the prompt.

Program Menus

If more information is needed in order to select a resource or parameter, a menu is displayed and the selection is from taken from the menu listing.  Menus have a couple of added features.  First, they can be nested so that the user can select more than one parameter to display from within a single program.  For example, you can select to plot temperature for the Midwest.  When you are done looking at this plot, you can select another variable such as temperature or go up a menu level and select a different region. Second, menus often have many more parameters to select than those listed.  The programs have predefined variable types, not all of which can be displayed in a simple menu.  You can still select the variable type but it will not appear on the menu.

When a resource is to be selected via a menu, a list of choices will appear.  Each menu item has a resource value associated with it.  By entering the number from the menu, you are essentially entering that value.  It is just an abbreviation for the value.

           Region Menu

     1: Contiguous US                   --------------------               
     2: New England                     10: Western Canada                
     3: Atlantic                        11: Eastern Canada                
     4: Southeastern                    12: Northern Canada               
     5: Midwestern                      13: North America                 
     6: Southern Plains                 14: Indiana                       
     7: Northwestern                    15: Lafayette                     
     8: Southwestern                  
     0: Return to previous menu         -1: Exit program                  

   Enter the region:

There are several ways of entering data at a menu prompt.  First, you can enter the number associated with the selection.  For example, the Midwest region can be selected by entering "5" at the prompt.  Second, the full menu listing can be there is the menu listing.  You could have entered "Midwestern".  There is also the resource value. To get a list of possible resource values, you can type "?" at the menu prompt:

   Enter the region: ?

The values are then listed and the prompt returns.  You can see that the associated value is "mw" so this could have been entered as well.  There are a number of preset regions that don't show up on the menu because of space concerns.  To get a full list of predefined regions, use the "list" command:

   Enter the region: list
    Abbr    Description
   us       Contiguous US                                     
   ne       New England                                       
   at       Atlantic                                          
   namer    North America
   nhem     North Hemisphere                                  
   shem     South Hemisphere                                  
   hi       Hawaii                                            
   ak       Alaska                                            
   globe    Global
   europe   Europe
   easia    East Asia                                           
   aust     Australia                                         
   wpac     West Pacific                                      
   antarc   Antarctica                                        

Often the values are short and mostly easy to remember. As you get more adept at using WXP, you will rarely look at the menu but will almost always enter the resource value or abbreviation.

Finally, there are non-menu resource values that can be selected.  For the region menu, a full plot domain value can be entered.  This really generalizes the use of menus to being interfaces into setting the resource:

   Enter the region: 40,-105,1.4

Here, the values represent the central latitude, longitude and the scale size of the plot (1 is appropriate for regional plots).

Most WXP resources can be set from the WXP prompt.  To view a list of set resources (those with values other than the program defaults), use the "set" command:

   Enter the variable: set
   Set resources
   default: /home/wxp/etc
   file_path: /home/wxp/etc
   data_path: /home/wxp/data
   con_path: /home/wxp/convert
   grid_path: /home/wxp/grid
   raw_path: /home/wxp/raw
   name_conv: name_conv
   current: la

You can then change any of these or set a new one by specifying the resource and its value:

   Enter the variable: set color_map=lblue

The resource is then set and the variable menu prompt returns.  This does not work for all resources because these resources have been already been used (for example filename).  This will work for those resources that have yet to be used such as colors, plot types, etc.

Finally, two more options are available. If the user wishes to exit the program, they can enter "-1" at the menu prompt and the program will terminate immediately and return to either the WXP shell or the operating system prompt. When working with menus and submenus, the user can enter "0" to return to a main menu when within a submenu. If the user is at the top menu level or main menu, this option will exit the program.

Typical Prompts and Menus

Most programs use a similar order to the prompts and menus.

  • Filename:
    In general, there is a prompt for filename in which a list of files is displayed and a prompt for the appropriate filename.
    List of available files:
    Enter the surface filename: 96112206

    The filename can be entered as the full path "/home/wxp/convert/96112206_sao.wxp", the name of the file "96112206_sao.wxp" or just the date portion of the file "96112206".  WXP handles putting the extension and the path on the filename if not specified.

    You can also specify latest for the filename.  If you enter "cu", the current data file is selected.  If the current data file does not exist, an error will be printed and the prompt will reappear.  If you enter "la", the last available file is searched for.  The current resource will have more information on the options.

  • Region:
    There is a prompt for display region, which represents the area, and the projection the plot will be drawn to.
            Region Menu
      1: Contiguous US                   --------------------               
      2: New England                     10: Western Canada                
      3: Atlantic                        11: Eastern Canada                
      4: Southeastern                    12: Northern Canada               
      5: Midwestern                      13: North America                 
      6: Southern Plains                 14: Indiana                       
      7: Northwestern                    15: Lafayette                     
      8: Southwestern                  
      0: Return to previous menu         -1: Exit program                  
    Enter the region:

    The region can be selected from this list, the full list of predefined regions (see "list" option) or a variable region can be selected:

    Enter the region: 40,-105,1.4

    The values represent the central latitude, longitude and the scale size of the plot (1 is appropriate for regional plots). A full plot domain value can be entered (see the plot_domain resource).

  • Forecast Time:
    The programs that involve forecast data will have a forecast time menu.
            Forecast Time Menu
      1: Initialized                     14: 4.5 day                       
      2: 6 hour                          15: 5 day                         
      3: 12 hour                         16: 5.5 day                       
      4: 18 hour                         17: 6 day                         
      5: 24 hour                         18: 6.5 day                       
      6: 30 hour                         19: 7 day                         
      7: 36 hour                         20: 7.5 day                       
      8: 42 hour                         21: 8 day                         
      9: 48 hour                         22: 8.5 day                       
     10: 60 hour                         23: 9 day                         
     11: 3 day                           24: 9.5 day                       
     12: 3.5 day                         25: 10 day                        
     13: 4 day                         
      0: Back to previous menu           -1: Exit program                  
    Enter the time: 

    There are several ways to specify the forecast time in addition to above menu values. You can specify a forecast time by using entering the time and its units:

    init - Initial time
    anal - analysis
    12hr - 12 hour forecast
    2day - 2 day forecast
    4.5day - 4 1/2 day forecast

    For more information on the forecast time specification, see the time resource.

  • Level:
    The programs that use upper air data either observational or forecasted, will have a level menu display (this replaces the region menu for simplicity).
            Vertical Level Menu
      1: Sea level                       12: 150 mb                        
      2: Surface                         13: 100 mb                        
      3: 1000 mb                         14: 70 mb                         
      4: 925 mb                          15: 50 mb                         
      5: 850 mb                          16: 30 mb                         
      6: 700 mb                          17: 20 mb                         
      7: 500 mb                          18: 10 mb                         
      8: 400 mb                          19: Tropopause                    
      9: 300 mb                          20: Max wind                      
     10: 250 mb                          21: Whole sounding                
     11: 200 mb                        
      0: Back to previous menu           -1: Exit program                  
    Enter the level: 

    The menu lists standard pressure levels but can be used to access other levels.  You can specify a level not on the menu by just entering a value and the units:

    sfc - Surface level
    sl - Sea level
    mwnd - Maximum wind level
    trop - Tropopause level
    430mb - 430 mb level (pressure)
    850-500mb - 850-500 mb layer
    310k - 310 K potential temperature level (isentropic)
    2000m - 2000 meter level (height)
    50m_ag - 50 meters above ground

    For more information on the level specification, see the level resource.

  • Variables:
    Each program has a predefined set of parameters either defined within the program or through a variable file:
            Variable Menu
      1: All Data                        13: Cloud Cover                   
      2: Temperature                     14: Pressure Tendency             
      3: Dewpoint                        15: 24 Hr Precip                  
      4: Wind Direction                  16: 24 Hr Maximum Temp            
      5: Wind Speed                      17: 24 Hr Minimum Temp            
      6: Wind Gust                       18: Snow Depth                    
      7: Wind Barb                       19: Wind Chill Temp               
      8: Sea Level Pressure              20: Heat Index                    
      9: Altimeter Setting               21: Relative Humidity             
     10: Present Weather                 22: Equiv Potential Temp          
     11: Visibility                      23: Convergence                   
     12: Cloud Ceiling                   24: Rel Vorticity                 
      0: Return to previous menu         -1: Exit program                  
    Enter the variable:

    This menu only lists a small subset of what WXP can calculate.  Again, you can list the resource values with the "?" but this will only list those values enabled in the menu.  If you want all the available values, you can use the "list" command.  You can also create your own variables and modify existing ones.  A simple example of this is changing the units of a variable.  For example, temperature on surface plots is plotted in Fahrenheit. To change it to Celsius, just put the desired units after the variable separated by a colon ":":

    Enter the variable: temp:C

  • Contour interval:
    To display gridded data, the user will be prompted for the contour interval:
    Contouring data for 500 mb Temperature (C)
    Maximum value: -6.519228
    Minimum value: -39.089241
    Enter the contour interval: 

    The maximum and minimum values of the grid are displayed in order for the user to select a decent interval.  A rule of thumb is to pick a contour interval that is 1/16th the range from the maximum to the minimum.  If the user wished the program to select an appropriate interval, enter "0".

  • Plot type:
    The type of plot is normally predefined.  Plotting programs will plot the data by default.  Grid programs have several possibilities for output plot type.  
    Color fill (C) or Line (L) contours:
    Vectors (V) or Streamlines (S):

    The first prompt will appear for the scalar grid fields asking whether the contours are to be regular line contours or filled contours.  The second appears when vector fields are to be plotted.  The plot selection is either arrowed vectors at each grid point or streamlines. Any of the plot type values can be entered (see the plot_type resource)

  • Device:
    The output device specifies whether the plotted information will appear in a window on the screen or spooled to the printer.

    Display (D) or Postscript (P):

    In general, the output will be displayed in a window so "d" will be selected.  If printed output is necessary, select "p" for postscript.  The output will either go to a file or spooled to a printer as specified by the wxpps_print or wxphp_out environment variables.
  • File parameter:
    In some cases, the program will produce output files.  This is true of decoders.  If the output file exists, whether it be a decoded file, a raw file or a grid file, the program will prompt you as to whether you want to overwrite the file, append to the file or to use the existing file in which the program normally exits.
    /home/wxp/convert/97030514_sao.wxp: exists overwrite (Y,N,Use,Over,App):

    The value "y" is the same as "Over" or overwrite the file. The value "n" is the same as "Use" which uses the existing file.

For further information about WXP, email technical-support@weather.unisys.com
Last updated by Dan Vietor on July 21, 1998