Hurricane Simon nears landfall in Mexico as Isaias weakens over US

Hurricane Simon is closing in on Mexico's Pacific coast, with forecasters warning it could make landfall near the port city of Manzanillo within hours. The storm has sustained winds of up to 240 to 250 km/h, or about 155 mph, with stronger gusts. It is a top-end category 4 hurricane, close to category 5. Satellite images show a well-defined eye about 60 miles offshore.

Residents along the coasts of Colima and Jalisco have been warned that waves as high as eight metres could bring storm surges and coastal flooding. People have been boarding up windows and doors. Panic buying has been reported in Puerto Vallarta and Manzanillo. Manzanillo is Mexico's biggest port, so the storm poses an economic risk as well as a threat to life.

Forecasters say the exact track is uncertain. If Simon moves inland, the mountains just inside the coast could weaken it quickly. If it skirts parallel to the coast, coastal areas could face catastrophic winds for longer, along with storm surge. Rainfall is also a major danger. Parts of Colima and Jalisco could see more than 30 inches, or 750 mm, of rain over a couple of days. That could cause life-threatening floods and mudslides, especially in mountainous areas and precarious neighbourhoods.

Acapulco has already seen some flooding, with cars floating down streets, according to reports from the area. The city has been hit hard by severe weather in recent years. Mexico is used to hurricanes, but preparations remain difficult. Poor neighbourhoods built on squatted land are particularly at risk from mudslides. The storm is also an early test for President Claudia Sheinbaum. In Jalisco, the powerful Jalisco New Generation Cartel may respond by looting or, as has happened before, by handing out relief and ordering people to stay home to present itself as a local authority.

In the United States, the aftermath of Hurricane Isaias is still being felt. At least four people have died in the south-eastern US after the storm battered the Gulf Coast with torrential rain. More than half a million homes lost power in Florida, Alabama and Georgia. Trees were brought down and houses damaged when Isaias made landfall. It was the first hurricane of the Atlantic season.

Isaias has since weakened to a post-tropical cyclone and is decaying rapidly. The system is centred over Tennessee and Kentucky, with heavy rain pushing north through the Appalachians. Flash flood warnings are in force in parts of North and South Carolina. The storm no longer draws energy from warm waters, so it is now mainly a threat of heavy rain and local flooding as it moves across the eastern US.

The two storms reflect a sharp split in the hurricane season. El Nino has warmed waters in the Pacific and changed wind patterns. Those winds are tearing storms apart in the Atlantic before they can form, leaving a record quiet Atlantic season in which Isaias was the first hurricane. On the Pacific side, the same pattern is helping storms gain strength, making Simon the latest in an active run.