I think there is a mistake in the legend of the rain accumulation. It has ft in the bottom right where I think it should be inches. That much rain would be biblical.
There is no mistake on this scale, and 3ft = 36in. It seems that makes a lot a rain, but on 10 days in tropical region that’s possible.
You can check the Rain accumulation predicted in some part of India today for the next 10 days.
Except at right end of the scale (3ft), all the other figures are in inches.
But I must say that this color scale is really imprecise at the right end of the scale. If you look at the color scale in detail via Settings > Customize color scale > Rain accumulation, you see that the pink color covers a very wide range from about 5in to more than 3ft (btw 300ft is a little bit crazy but it’s like a logarithmic scale)
I had the same confusion as the OP. It would be more clear to use "36" rather than 3ft, since the units are in inches. I was confused with units of in on the far left and ft on the far right.
I guess you know how many inches 3ft stand for?