Washington, Oct 25 : The US National Hurricane Center (NHC) warned that hurricane Otis has become an "extremely dangerous" Category 4 storm as it was fast approaching the Pacific coast of southern Mexico. According to its latest update, the NHC said the hurricane's winds have now increased to near 233 km/h and will strengthen to a "potentially catastrophic" Category 5 storm when it makes landfall on early Wednesday, reports the BBC. The Center has also warned of "destructive waves" and heavy flooding in coastal areas, including the popular Acapulco resort. A hurricane warning is now in effect for a 350 km-long stretch of coastline between the coastal towns of Zihuatanejo and Punta Maldonado in the state of Guerrero. "A potentially catastrophic storm surge is expected to produce life-threatening coastal flooding near and to the east of where the centre makes landfall. Near the coast, the surge will be accompanied by large and destructive waves," the BBC quoted the NHC as saying. It added that Otis was expected to produce up to 15 inches of rainfall on Friday across Guerrero and western coastal areas of the neighbouring Oaxaca state. The NHC also forecast that "rapid weakening will occur after landfall". Ahead of the hurricane's arrival, Guerrero's authorities have been preparing emergency shelters, while schools across the state were closed. /IANS