Ah, yes. This brings back painful memories. As soon as my daughter found her scream (she was around 12 months I guess) she learned to use it when she was angry or upset. We aren't a screaming family so it was particularily frustrating. We had to ride it out. It is SO effective because it is so visibly upsetting to us. They get an immediate reaction from almost everyone, especially stressed out mom (aka me!). She needs to start to get no reaction from it. I would suggest... "Little girls who scream get bedroom time." Then into her crib she goes EVERYTIME she even screams a litte. Let her scream until she is done. Then go in and say "are you done?" When she says yes pick her up and say "Yeah, little girls who don't scream get to come have fun with mommy!". If you have a stubborn little girl like I do, it might take a month or two. If you have a complacant child, she might figure it out the first time (how lucky you would be!). The hardest part was when we were out. We immediately left the park, playgroups, whatever. Or, if you are with people that you can trust, you can give her bedroom time there to (or car time - that is what she got at grandma and grandpas. I could see the car from the house so she could scream in the car and no one could hear her. Obviously this doesn't work on a warm day or if you feel in any way she is in danger in the car without you in it). But I had to put her in her car seat in the car because my elderly parents couldn't handle the screaming in their home. I would go check on her and say "are you done?" Sometimes my stubborn child would say "no" so I would just say "OK, scream until you are done!" and close the door and go back in the house (she could see me walk back in the house." Then I would go back and when she was done I would again say "yeah, little girls who are calm get to come have fun at grandma and grandmas.!"
Also, when she was not quite to a scream but was crying we talked about being calm (actually since she was a baby). We taught her as a baby to take a deep breath to calm down. So we usually talked about this at some point to. If I ask her if she is calm she can almost always immediately turn off the tears, take a deep breath, and say yes. My parents were always amazed with that one. Sometimes I am even floored by how fast she can stop crying if she has the right motivation.
Good luck. I had more than one friend tell me they could not deal with that if their child did that. But if you can stay calm and make it her problem, not yours. Give her natural consequences EVERYTIME for it, you can kick it!