Yep, they know the downpour is coming, and they mock us. Mine will hide under that bush at the furthest side of the yard until the downpour starts, then will scream at me to come escort them back to their cozy dry coop.
Jerks.
Pecking order can be brutal, but if they aren’t drawing blood I’d leave them be.
Also, she may be detecting an illness in Thelma, that’s why my #2 hen went after my head hen.