LOOP                                                                            
ERAS                                                                            
TXT3 ---------------------------------------------------------------             
TXT4                12/24h Forecast Changes NGM/NAM/GFS            -             
TXT5 ---------------------------------------------------------------             
4SEC                                                                            
TXT9 -------------------------------------------------------------------------- 
TXTA This menu is intended to allow forecasters to evaluate model changes     -
TXTB within a particular model run.  Various fields are examined 12 and 24    -
TXTC houlry, are overlayed, and difference fields computed.  The macro can    -
TXTD be run on any model data.                                                -
TXTE                                                                          -
TXTF                                                                          -
TXTG                                 <RETURN>                                 -   
TXTH --------------------------------------------------------------------------
ENDL
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TEMP GRTN 400
ERAS
TXT4 --------------------------------------------------------------------------                                                          -
TXT5 IN ORDER TO RUN THESE MACROS YOU MUST:                                   -
TXT6                                                                          -
TXT7 1) LOAD ONLY THE DATA FILE YOU WISH TO ANALYZE (NGM/NAM/GFS).            - 
TXT8            Unlike other comparison fields, you do not have to load       -                                                                    
TXT9            multiple files to run this macro.  Since 12 and 24 h          -
TXTA            differences are computed for a specific model run, only one   -
TXTB            data file must be loaded.                                     -
TXTC                                                                          -
TXTD                                                                          -
TXTE 2) NOTE DIFFERENCES ARE COMPUTED AS OLDEST MINUS NEWEST.                 -
TXTF          All differences are computed as OLDEST MINUS NEWEST.  Hence,    -
TXTG          for 12 h fields, the first period encompasses the period        -
TXTH          from T+00 to T+12.  The difference field is computed as         -
TXTH          F12 MINUS F00.  The same technique will be applied to 24 h      -
TXTI          difference fields.  The MACROS will step you through the        -
TXTJ          entire model run.                                               -
TXTK                                                                          -
TXTL          If, for example, we wanted to examine the height changes        -
TXTM          from T+00 to T+48 in 12h increments for an entire model run,    -
TXTN          you would select menu item 1.  The difference field shown would -
TXTO          be F12-F00 first, followed by F24-F12, F36-F24, and F48-F36.    -
TXTP          For the 24 h differences, the first field shown would be the    -
TXTQ          F24-F00 followed by the F36-F12 and F48-F24.                    -
TXTR                                                                          -
TXTS                                    <RETURN>                              -
TXTT --------------------------------------------------------------------------
ENDL
LOOP
TXT4 --------------------------------------------------------------------------                                                    -
TXT5                                                                          -
TXT6    THERE ARE TWO TYPES OF CHARTS AVAILABLE IN THIS SECTION...            -
TXT7                                                                          -
TXT8    1) 12-H COMPARISON CHARTS -  These charts compare subsequent 12 h     -
TXT9                    periods for an entire model run.  The T+00 h field    -
TXTA                    is displayed, T+12 h field overlayed.  The 12 h       -
TXTB                    difference is then computed and displayed.  You will  -
TXTC                    be stepped through the entire model run in 12 h       -
TXTD                    increments.                                           -
TXTE                                                                          -
TXTF    1) 24-H COMPARISON CHARTS -  These charts compare subsequent 24 h     -
TXTG                    periods for an entire model run.  The T+00 h field    -
TXTH                    is displayed, T+24 h field overlayed.  The 24 h       -
TXTI                    difference is then computed and displayed.  You will  -
TXTJ                    be stepped through the entire model run in 24 h       -
TXTK                    increments.                                           -
TXTL                                                                          -
TXTM                                                                          -
TXTN                                                                          -
TXTO                                                                          -
TXTP                                                                          -
TXTQ                                                                          -
TXTR                                     <RETURN>                             -
TXTS                                                                          -
TXTT --------------------------------------------------------------------------
ENDL
LOOP
ERAS
TXT4 ---------------------------------------------------------------------
TXT5 THE PURPOSE OF THIS MENU IS TO ALLOW FORECASTERS TO STEP THROUGH AN -
TXT6 ENTIRE MODEL RUN IN EITHER 12 OR 24 H INCREMENTS TO DISPLAY,        -
TXT7 QUANTITATIVE CHANGES IN MODEL FORECAST VARIABLES.                   -
TXT8 ---------------------------------------------------------------------
ENDL
