Even as drought makes the headlines in the western United States, new research warns that public officials should also be planning for a an opposite risk: catastrophic floods. A massive winter rain and snow storm could hit California this century, with widespread damage to the country’s most populated state. That’s according to a new study from researchers at the University of California, Los Angeles. The Pacific coast is no stranger to heavy rainfall, but climate change is strengthening the plumes of tropical moisture that can hit California like a firehose. At the same time, the nature of precipitation is changing – it’s falling more as rain than snow, which means rivers rise faster than usual in the winter. Together, the two trends are a major threat.