The woman looked exhilarated but concerned as she met us coming down the Swiftcurrent Pass trail. “You’d best be careful heading up to the pass. There’s supposed to be a big thunderstorm today. An L4.” That term puzzled me until the middle-aged hiker clarified that the “L” rankings indicated the severity of storms. My companion Kitty explained that they had L5 events back in her native Florida, when the air felt utterly alive with charged particles and the ground would shake continuously as thick thunderbolts slammed into the earth.