Hurricane Otis turned into a monster overnight. Forecasters don't know why

Hurricane Otis took everyone by surprise, including forecasters. The lingering question is, why?

Hurricane Otis turned into a monster overnight. Forecasters don't know why
A satellite infrared image shows Hurricane Otis making landfall in Mexico, with heavy bands of rain shown in red.

Hurricane Otis took everyone by surprise, including forecasters. The lingering question is, why?