Mood swings bringing everyone down - how to react?

[Meanderer]

My daughter is 14 and her emotions are always quite ‘big’ ... when she’s up she’s loud and cheery, when she glowers the rest of us really feel it too. Her moods, pleasant or dark seem to affect us all. I don’t know how to handle it - whether to be compassionate and patient or tell her to rein it in and stop inflicting her moods on us. I went to quite a bit of effort to arrange a treat tonight and half way through she started glowering and then disappeared off. She’s just sworn at me, clearly furious about something but insisting she doesn’t know why. Her best friend is here and it’s really awkward for her as she gets stuck in the middle, daughter not speaking to her either! Luckily me and friend are close so we are kind of ok but both clearly tiptoeing around my daughter.

Should they not be in bed? Are they not going to school tomorrow?

Stop pandering to your daughter's shit behaviour. It is perfectly fine to feel moody, angry, whatever. It is NOT fine to act like an arsehole and create an atmosphere. You need to demand that she learns to recognise and manage her emotions. If she's feeling negatively, she has to take the responsibility to remove herself to her room and compose herself. It is ridiculous to allow her to treat you without respect. As for her friend, I would send her home. Why are you allowing her to be treated so poorly as well? It's time to take control.

Bari they have an inset day today, hence the special night - belated midsummer celebration. They were in bed by 11.30 but I do think tiredness contributed to the low mood!
Aquamarine thanks for taking the time to reply - I think from your overall tone we have different parenting styles - but I agree it’s not ok for her to inflict her anger on us. I guess I would rather find strategies to work around it in the moment, as dealing with it in the heat just escalates things, as she panicks and gets defensive and digs herself into a corner. She always comes to find me and apologises as soon as she ‘comes down’. Her swearing was an expression of anger rather than of disrespect. Her friend is pretty much family to us so there is no need to send her anywhere, we need to deal with it as a family type thing. If I described this as a stepfamily dynamic that might make it clearer how I would want to tackle it.