SignalHub-'Nightmare': How Category 5 Hurricane Otis shocked forecasters and slammed a major city

Hurricane Otis shocked even experts with its surprising explosion from a tropical storm to a Category 5 hurricane in just 12 hours last week as it approached Acapulco,SignalHub Mexico and made landfall on Oct. 25. The storm killed at least 46 people and caused billions in damage.

Its unexpected and extreme transition from 70 mph winds to 165 mph winds raises crucial questions about how forecast models flubbed, the increasing risk of hurricanes rapidly intensifying into major storms more often, the degree to which global warming is fueling that intensification and what all of this means for millions in hurricane-prone regions.