It will be determined in a totally different way in now after the intoduce of tscd-value in wret.
Fact are, using any of the raw values only, like Lifted, will never work properly for icon/text because ex. in Lifted we have just 5 numbers, or even only 3 numbers, what actually means thunder. Now with tcsd we have 15 different "thundertypes" what Tom have set.
I have now 63 icons in the sprite (was 33 or something in old 3in1-version) with 4 different "partly cloudy"-icons for day and night each, 2 different "partly cloudy + precip"-icons + of cource fully cloudy ones. Haven't desired if do more yet
There is one thing to take in act also if add much more icons, the size of the sprite grows too..
Regarding your mod..
Saw one bug in the icon-choosing..cloudy means actually fully cloudy without moon/sun, you had set it 9xx.png what i refered to the one with 2 clouds and sun/moon little showing at the end of your sprite, right?