Published by G.P. Putnam's Sons Books For Young Readers.
Emsy has always lived in sunny California, and she’d much rather spend her days surfing with her friends or hanging out with her girlfriend than honing her powers as a fire elemental. But when members of her family’s coven back east are murdered under mysterious circumstances that can only be the result of powerful witchcraft, her family must suddenly return to dreary upstate New York. There, Emsy will have to master her neglected craft in order to find the killer . . . before her family becomes their next target.
... and found family. It's not really deep though, and the witch categorization is pretty similar to the one in Isabel Sterling's novels (no surprise, given that the authors are friends).
