Firebaugh, Calif., sitting right on the San Joaquin River, is a great place to raise a family, says city manager Ben Gallegos. He’s lived in this Central Valley community for most of his life. But now he’s preparing the city for a force of nature potentially more destructive than the fires and drought Californians are used to — a megastorm. They form out at sea as plumes of water vapor thousands of miles long. As they reach land, they dump rain and snow for weeks at a time, causing devastating flooding.