Display user specified contour levels in GrADS

I would like to know how to display specific contour levels on the colorbar. For example, as shown in the schematic above taken from pivotalweather, shows a colorbar for precipitation values that are not really equally spaced. I would like to know how to achieve a similar result with GrADS.

PS: I use the cbarn.gs and the xcbar.gs script sometimes.

You need to use the original color set of GRADS for this.

THREE steps:

1). Set the color using the 'set rgb # R G B'. You need the RGB of the colors in your color bar. Since there are 15 default colors in GrADS, you should start the # at 16.

Check this link for details of the colors: http://cola.gmu.edu/grads/gadoc/colorcontrol.html

2). You need to set the color level as follows:

 set clevs 0.01 0.05 0.1 0.02 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.2 1.4 1.6 1.8 2 
 2.5 3 3.5 4 5 6 8 15

3). You need to specify the colors based on your defined RGBs.

 set ccols 16, 17, 18,....etc.