There is a lot of stress in the life of a teen girl. First, the physical stresses. Her body is changing daily. Compound on that the exterior stresses: she needs to get into a good college; she needs to decide if she's a jock or a geek; she needs to navigate the social world, and you've got a whole lot weighing down on a girl every day. Coping with stress is key to emotional maturity.
Wouldn't it be nice to just say that and they'd go away forever? Girls can really go off the deep end over things that might completely surprise you. You're cooking pasta for dinner and suddenly she's screaming about how you didn't ask her if she wants pasta. The anger seems extreme for the situation. This is most likely a case of your daughter using you to relieve her stress. Think of it this way: out in the world and at school, she has to act better. She cannot trust the world to see through any “breakdowns” and still admire her. But you? You are the bearer of unconditional love. That means, if she has to blow off steam, you're the one to do it at. But that does not mean you need, or should, become her punching bag.
If your daughter seems to lose it over something that confuses you, insist she spend some quiet time in her room or in the yard before addressing you again. Find a “big girl” type of “time out” to help her calm down.
While it may seem silly to you (“I wasn't invited to Susan's party”), the stressors in your daughter's life are more than real to her. Don't ever pooh-pooh them, even if you think they are silly. At the same time, don't feed into it, telling her she should be mad or upset. Rather, work toward helping her let the stress go and then assessing the situation.
You'll need to set that example yourself as well. Learn self-control, and then make an effort to be an example for your daughter to mirror.
Stress affects bodies. You've felt it: the muscles in your back or neck or even face stiffening up as you stress more and more about things. Girls are no exception. And sometimes, relieving the body stress can lead to helping your daughter relax more about the entire situation. Consider signing up for a parent-child yoga class. Not only will you have a special time together, but she will learn breathing and stretching techniques that you can suggest she use during stressful situations.
Caffeine can exacerbate stress, and more and more teens are drinking caffeinated beverages each morning and afternoon. Encourage your daughter to stay away from these drinks (and remember, caffeine is in coffee, tea, chocolate, cola, and other places too).
If you see your daughter building up to a stressful moment (studying for a test; hanging up after a bad phone call), encourage her to lay down in a quiet and semi-dark place and breathe in through her nose, out through her mouth. Sometimes, five to ten repetitions of this breathing is enough to begin the calming process. And the breathing is something she can do without being noticed right in the middle of her school or out in a social situation. The outdoors can be a help too. If she's going off the deep end, insist on taking a long walk with her, even if it's just up and down your street. The rhythm of the walking and the breathing will soothe her stresses, and again, she'll learn a life skill for coping with stress. In the end, she has to realize, stress is a part of life. As always, it's what you do with it that matters.