QUINCY, Calif.—Thousands of Northern California homes were threatened Sunday by the nation’s largest wildfire. Thunderstorms that moved in starting Friday didn’t produce much rain but whipped up winds and generated lightning strikes across the northern Sierra where crews were battling the month-old Dixie Fire. “We’re definitely still dealing with the possibility of lightning. Winds are all over the place. Things are going to be pretty unstable for the next couple days,” said fire spokesman Edwin Zuniga. Gusts of up to 50 mph (80 kph) on Saturday pushed flames closer to Janesville, a town of about 1,500 people just east of Greenville, the small gold rush-era community decimated by the fire 10 days ago. James Reichle evacuated from Greenville and has been sleeping with his dog in a trailer outside a church. His home survived the flames but he’s been unable to return because the roads are closed. He said he …