SFCMG - Displays a surface meteorogram
   SFCMG id nhours <keywords>
Parameters:
   id | station ID to plot
   nhours | number of hours to include in meteorogram; the ending time
            is specified in the TIME keyword (def=24)
Keywords:
   COLor=t td p cld win wx pcp vis bg | graphics color levels for each
              of the parameters, where t=temperature, td=dew point,
              p=pressure, cld=clouds, win=wind, wx=weather,
              pcp=precipitation, vis=visibility, bg=background grid
              (def=5 4 2 7 3 3 4 3 8)
   CRAnge=min max unit | minimum and maximum cloud levels, and units
                         (min def=0; max def=max cloud height; unit def=FT)
   DATaset= | point dataset name and position; specify as alias.position
              or group/descriptor.position where position is a positive
              integer (absolute position), 0 or a negative integer
              (relative position), or ALL   (def=RTPTSRC/SFCHOURLY.ALL)
   DAY= | ending day of data to plot (def=current)
   EG=NO | does not erase graphics frame before plotting (def=YES)
   GRA= | graphic frame number to display meteorogram (def=current)
   INT= | data hour interval; useful for decluttering the plotted data;
          for example, use INT=6 to plot every 6th hour of data (def=1)
   LATest=LEFT | plot latest data on left side of meteorogram
         =RIGHT | plot latest data on right side of meteorogram (def)
   PRAnge=min max unit | minimum and maximum pressure, and units
                         (min and max def=calculated; unit def=MB)
   PTYpe=ALTM | use altimeter setting for pressure values (def)
        =SLP | use sea level pressure for pressure values
   TDAy=CAL | print calendar day on title and day labels (def)
       =JUL | print Julian day on title and day labels
   TIMe= | ending hour of data to plot (def=current for current day;
           def=23 if any other day is specified in DAY keyword)
   TRAnge=min max unit | minimum and maximum temperature, and units
                         (min and max def=calculated; unit def=F)
   UNIt=A | plot in American units: visibility in miles, precipitation
            in inches, and wind speed in knots (def)
       =M | plot in metric units: visibility in kilometers, precipitation
            in millimeters, and wind speed in meters/second
Remarks:
   SFCMG displays a meteorogram (time series plot) of surface hourly data.
   The meteorogram draws temperature, dew point and pressure traces; and
   plots cloud coverage/heights, wind direction/speed/gusts, weather,
   precipitation and visibility.

   SFMG plots the first weather reported in the weather group. For
   example, if the weather group shows heavy snow and blowing snow
   (+SN BLSN), only the heavy snow symbol is plotted.
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