weather forecast August 16, 2020 10:36 am Explainer: How Lightning Forms NBC Bay Area meteorologist Vianey Arana explains how lightning forms and why it struck the Bay Area over the weekend. US & World Videos 2:51 Cinthia's forecast: Spring storm, cooler temperatures 2:58 Jeff's Forecast: Saturday rain drops temps and brings major Sierra snow 3:25 Bay Area Forecast: Storm brings rain, colder temps and big Sierra snow 2:31 Forecast: Rainy Saturday ahead 2:12 Kari's forecast: Rainy Saturday ahead