Chance of cyclone west of Yucatan Peninsula still 70 percent: NHC Wed Sep 18, 2013 7:45pm EDT (Reuters) - An area of low pressure over the extreme southwestern Gulf of Mexico, just west of the Yucatan Peninsula, still has a 70 percent chance of becoming a tropical cyclone in the next 48 hours, the U.S. National Hurricane Center (NHC) said in its latest advisory. Environmental conditions are expected to be conducive for the formation of a tropical depression on Thursday, and this disturbance will likely spread heavy rain over portions of eastern and southern Mexico over areas already impacted by torrential rain during the past several days, the agency said. Reporting by Shruti Chaturvedi in Bangalore; Editing by Gary Hill