A Pacific cyclone dubbed Polo exploded from a tropical storm into a powerful Category 5 hurricane in less than 24 hours on Tuesday (Sept. 22), with winds reaching speeds of 180 mph (290 km/h). Now drifting off the southwest coast of Mexico, Polo has been downgraded to a Category 4 storm but remains "a very powerful major hurricane," the National Hurricane Center (NHC) said in an update Wednesday (Sept. 23).As Polo moves northwest, it is expected to drive torrential rainfall on parts of Mexico's southwest coast. Although the storm is not predicted to make direct landfall, the NHC has warned that heavy rain may produce life-threatening flooding and mudslides, as well as extremely hazardous oce...