Adult female characters in Avatar the Last Airbender

I just watched Avatar: the Last Airbender and it was awesome (see my lj for squee) but something struck me in the third season, when the teenage characters started to interact more with their adult allies en masse.

While many of the teenage/child characters are female, and are written really well, hardly any of the adult ones are. There's a lot in the world, in the form of off-screen or dead mothers etc, or characters who show up for a single episode. But I can think of hardly any female characters over 20 who appear on screen for more than one episode, and none who really DO anything apart from the grandmother who is only at the very beginning of the series.

( Spoilery listing )