LOOP                                                                            
ERAS                                                                            
TXT3 ---------------------------------------------------------------             
TXT4          NGM/NAM FORECAST COMPARISONS/DIFFERENCES             -
TXT5 ---------------------------------------------------------------             
4SEC                                                                            
TXT9 -------------------------------------------------------------------------- 
TXTA This menu is intended to allow forecasters to examine model output for   -
TXTB various parameters simultaneously using both the NGM and NAM.  Difference-
TXTC fields are computed to highlight model/model deviations.                 -      
TXTD                                                                          -
TXTE                                 <RETURN>                                 -   
TXTF --------------------------------------------------------------------------
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TEMP GRTN 400
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TXT4 --------------------------------------------------------------------------                                                          -
TXT5 IN ORDER TO RUN THESE MACROS YOU MUST:                                   -
TXT6                                                                          -
TXT7 1) LOAD THE NGM and NAM FILES YOU WISH TO COMPARE (TWO FILES).           - 
TXT8          When you entered WINGRIDDS, you entered a file name, likely     -
TXT9          the most recent file.  If this was an NGM file, you may compare -
TXTA          it with the corresponding NAM file by loading it in FILE 2.  To -
TXTB          do this, use the "OPEN" command from the WINGRIDDS command line.-      
TXTC          (eg. OPEN FIL2 <RETURN>, AP199312.NAM will load the NAM file    -
TXTD          from 19 April 1993, 1200 UTC in file2).  Once both files are    -
TXTE          loaded...type "FILS".  A list of files will appear.  The NGM    -
TXTF          data file should be in File 1 and the corresponding NAM file in -
TXTG          file 2.                                                         -
TXTH                                                                          -
TXTI          *** IT IS IMPORTANT THAT THE NGM FILE BE LOADED IN FILE 1 AND   -
TXTJ              THE NAM FILE IN FILE 2.  SINCE DIFFERENCES WILL BE TAKEN    -
TXTK              WITH RESPECT TO FILE NUMBERS AND NOT FILE NAMES ***         -
TXTL                                                                          -
TXTM                                   <RETURN>                               -
TXTN --------------------------------------------------------------------------
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TXT4 --------------------------------------------------------------------------
TXT5                                                                          -
TXT6 2) NOTE DIFFERENCES ARE COMPUTED AS NGM MINUS NAM                        -
TXT7          All differences are computed as NGM MINUS NAM.  Hence, if you   -
TXT8          wish to examine the 500 mb height field difference for the 12 h -
TXT9          forecast of both models and compare, set the forecast time (F12)-
TXTA          before executing the MACRO and hit MENU OPTION 1.  The 12 h,    -
TXTB          500 mb height field for the NGM will be displayed followed by   -
TXTC          the 500 mb height field for the NAM.  The difference between the-
TXTD          models will then be computed as F12 NGM -MINUS- F12 NAM.        -
TXTE                                                                          -
TXTF          Using this convention, the conclusions made will be relative to -
TXTG          to the NGM (sign convention) but can be interpreted for the NAM -
TXTH          as well.  For example if the NGM forecasts a 500 mb height of   -
TXTI          5780 gpm and the NAM, a 500 mb height of 5730 gpm (both for a   -
TXTJ          12 h forecast) the difference would be:                         -
TXTK                         5780 (NGM) - 5730 (NAM) = +50 gpm                -
TXTL          Hence, the NGMs 500 mb height forecasts is 50 gpm greater (+50) -
TXTM          than the corresponding NAM forecast.                            -
TXTN                                                                          -
TXTO                                                                          -
TXTP                                    <RETURN>                              -
TXTQ --------------------------------------------------------------------------
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TXT4 --------------------------------------------------------------------------                                                    -
TXT5                                                                          -
TXT6    THERE ARE SEVERAL TYPES OF CHARTS AVAILABLE IN THIS SECTION...        -
TXT7                                                                          -
TXT8          All charts are discribed by individual help files listed in     -      
TXT9          this menu.  Comparisons between heights, temperatures, RH,      -
TXTA          Q-vectors, Divergence etc can all be facilitated by executing   -
TXTB          the respective menu option listed in ALT-F11.                   -
TXTC                                                                          -
TXTD          *** NOTE...THESE MACROS ARE NOT 48 H LOOPS.  YOU MUST SPECIFY   -
TXTE              THE FORECAST HOUR YOU WISH TO ANALYZE/COMPARE PRIOR TO      -
TXTF              EXECTUION OF THE MACRO.  THUS, IF ALL YOU ARE INTERESTED IN -
TXTG              IS THE DIFFERENCE THE MODELS HAVE AT 48 H, YOU CAN PRESET   -
TXTH              THE FORECAST HOUR (F48) AND EXECUTE ALL YOUR MENU OPTIONS   -
TXTI              WITH THE SAME TEMPORAL CONTINUITY ***                       -
TXTJ                                                                          -
TXTK                                                                          -
TXTL                                                                          -
TXTM                                                                          -
TXTN                                                                          -
TXTO                                                                          -
TXTP                                     <RETURN>                             -
TXTQ --------------------------------------------------------------------------
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TXT4 ---------------------------------------------------------------------
TXT5 THE PURPOSE OF THIS MENU IS TO ALLOW FORECASTERS TO COMPARE         -
TXT6 MODEL OUTPUT BETWEEN THE NGM AND NAM TO INFER FORECAST DIFFERENCES. -
TXT8                                                                     -
TXT9 COMPARISONS CAN BE MADE FOR THE FORECAST HOUR OF CHOICE BETWEEN     -
TXTA 0 AND 48 H.                                                         -
TXTB                                                                     -
TXTC COMPARISONS CANNOT BE MADE WITH THE GFS DUE TO GRID SIZE/ORIENTATION-
TXTD DIFFERNECES.                                                        -
TXTE                                                                     -
TXTF ---------------------------------------------------------------------
ENDL