I am incredibly thankful for your answer, but it is still frustrating to deal with her. There is nothing like a sulking obstructing preteen to ruin the well-being of the entire family. She is a master of manipulation. When required to do chores for other people (nieces), she initially is sweet and demure, then suddenly has a Grade A temper tantrum in front of everybody. She is used to getting what she wants simply by having a tantrum or being nasty. She refuses to take responsibility for her behavior. It's everyone else's fault. Does it go away?
You aren't the first to ask me that, and I'm sure you won't be the last. For the most part, moodiness is common problem for girls going through adolescence. The surging hormones are difficult to get used to or control. Just ask your husband if he notices your mood swings each month. If he's not too afraid to say anything, he'll probably roll his eyes and think, "What did I do to deserve this!" And you have experience; your daughter doesn't.
Another contributing cause is that teenagers are not able to judge other people's body language accurately. A recent study showed that teens can look at facial expressions and overrate the mood being expressed. A look of annoyance can be seen as open hostility or raging anger. It takes several years for the teenage mind to make the right connections, but in the meantime, they are making bad decisions based on inaccurate input.
If it is not allowed to develop into a habit, she will gradually learn to control her moods. For many girls it settles down in their late teenage years. For parents at the leading end, five or more years of volatile moods seems to be forever, but you'll survive. What we need to do is keep the battle wounds down in the process.
I know you thought you were past this stage, but treat temper tantrums as you would a two year old. Many times temper tantrums are for show. People using them need an audience to manipulate. The proper response is to calmly state that you are not interested, and send her off where there is no audience, such as her room. Too many parents cave because they are embarrassed or would rather avoid a fight. She knows this, that is why she uses these methods to get her way. Now you know this. As you see her putting on a display, tell yourself it is not really real. Think of it as watching a movie and start rating her performance. This little technique will help separate her emotions from yours. Whatever you do, never give her what she demands with a tantrum or nastiness. Even if it would have been reasonable, the use of those techniques means an unqualified "No." If you and your husband stick to this, then she'll give up. If you consider and grant reasonable request presented nicely, she'll turn to those methods. However, if you give in every once in a while, it will take a much longer time to break her of these bad habits.
A child can learn just about anything if you present it factually, and clearly. And above all -- consistently. You're SO right. Thank you.