I see. And does the Storm page specify the mass of the clouds as well? Me and Zaara are discussing whether it means spitting a hurricane over a thousand kilometers or condensing it. It seems likely that we'll go with CAPE but it would be good to leave all bases open.
Though since your feat seems to be from a book, perhaps you could upscale the size from this. Rainfall is more or less proportional to area so (1000/665)^2*6e14 = 1.3567754e15 Joules per second or High 7-C