It's Tuesday: longtime NBC weatherman Al Roker has a new book about the most catastrophic flood in US history — the Johnstown flood of 1889, which killed more than 2,200 people in the Pennsylvania steel town. Roker says the story of that flood contains lessons about climate change, greed, American infrastructure, and the power of mother nature. Email samsanders@npr.org and tweet @NPRItsBeenAMin with feels.