When Sonny Dunes, a So-Cal meteorologist who knows only sunshine and 72-degree days, has an on-air meltdown after she learns she’s being replaced by an AI meteorologist (which the youthful station manager reasons "will never age, gain weight or renegotiate its contract."), the only station willing to give a 50-year-old another shot is one in a famously non-tropical place--her northern Michigan hometown.   Unearthing her carefully laid California roots, Sonny returns home and reaclimates to the painfully long, dark winters dominated by a Michigan phenomenon known as lake-effect snow. But beyond the complete physical shock to her system, she s also forced to confront her past: her new boss is a former journalism classmate and mortal frenemy and, more keenly, the death of a younger sister who loved the snow, and the mother who caused Sonny to leave.   To distract herself from the unwelcome memories, Sonny decides