Claim: A ARkStorm is a "megastorm" that could devastate California, returning every 150-200 years.
Evidence: An ARkStorm (for atmospheric river 1,000 storm) is a hypothetical but scientifically realistic "megastorm" scenario developed and published by the Multi Hazards Demonstration Project (MHDP) of the United States Geological Survey, based on historical occurrences. It describes an extreme storm that could devastate much of California, causing up to $725 billion in losses (mostly due to flooding), and affect a quarter of California's homes. Based on the intervals of known occurrences, ranging from 51 to 426 years, scientists have concluded that these events have a mean return period of around 150–200 years.