[Color index 0 = white / color index 1 = black]

[Download drought_severity.rgb file and put in $NCARG_ROOT/lib/ncarg/colormaps]

Sample NCL script usages:

;---Using the color map to define colors for contours or vectors
  res@cnFillPalette = "drought_severity"
  res@vcLevelPalette = "drought_severity"

;---Reading the colormap into an N x 4 (RGBA) array
  cmap = read_colormap_file("drought_severity")

;---Using the color map to define a color map for the workstation
  gsn_define_colormap(wks,"drought_severity")