Mexico: Tropical Storm John tracking west-northwestward off the coast of Guerrero State early Sept. 26 /update 4

Tropical Storm John is tracking west-northwestward off the coast of Guerrero State, Mexico, early Sept. 26. The storm previously made landfall as a Category 3 hurricane south-southwest of Marquelia late Sept. 23 before weakening into a tropical depression and moving back out into the Pacific Ocean Sept. 24. As of 03:00 CST, the system's center of circulation was approximately 105 km (65 miles) south-southwest of Lazaro Cardenas, Michoacan State.

Forecast models indicate that John will strengthen into a Category 1 hurricane Sept. 26 and then a Category 2 hurricane late Sept. 26 as it tracks northwestward toward the coast of Michoacan State. The system is expected to make landfall near Maruata in Michoacan early Sept. 27. After landfall, John is forecast to weaken into a tropical storm as it tracks northwestward over western Michoacan State early Sept. 27, before weakening further into a tropical depression as it moves across Colima State and into Jalsico State through Sept. 27. The system is expected to transition into a post-tropical cyclone as it turns to track west-northwestward and moves back out into the Pacific Ocean early Sept. 28. Some uncertainty remains in the track and intensity forecast, and changes could occur over the coming days.

As of early Sept. 26, authorities have issued the following watches and warnings:

• Hurricane Warning: Tecpan de Galeana to Punta San Telmo

• Tropical Storm Warning: Punta Maldonado to east of Tecpan de Galeana and west of Punta San Telmo to Manzanillo

Hurricane conditions are expected along the coast within the hurricane warning area by late Sept. 26 or early Sept. 27, with tropical storm conditions likely Sept. 26. A dangerous storm surge is forecast to produce coastal flooding near and to the east of where the center of the system makes landfall. Near the coast, the surge will likely be accompanied by large and destructive waves.

Forecast models indicate that the system will produce additional rainfall totals of 25-50 cm (10-20 inches), with localized higher amounts of around 76 cm (30 inches), across parts of Guerrero, Michoacan, and Oaxaca through Sept. 27. Swells from the system will continue affecting the coast of southern Mexico over the coming days. The swells may cause dangerous surf and rip currents.

Several ports are closed to small vessels ahead of John's approach, including Acapulco, Puerto Marquez, and Zihuatanejo in Guerrero State and Lazaro Cardenas in Michoacan State. Hundreds of shelters have been opened across parts of Guerrero and Michoacan states and civil protection authorities have issued the highest red-level alert in Guerrero. Schools are closed across parts of Guerrero, Michoacan, and Oaxaca. Flooding, landslides, blocked roads, power outages, and other associated disruptions were reported across parts of Guerrero and Oaxaca after the storm first made landfall. Authorities have reported at least four storm-related fatalities and at least 300 homes have been flooded in parts of Guerrero State. Additional adverse weather associated with the storm will likely exacerbate the situation in affected areas.

Sustained heavy rainfall could trigger flooding in low-lying areas and those with easily overwhelmed drainage systems. If weather conditions prove hazardous, localized evacuations as well as additional flash flooding and landslides are possible.

The inclement weather could trigger localized business, transport, and utility disruptions and render some bridges or roadways impassable. Flight disruptions at regional airports and temporary closures of ports are also possible. Stagnant pools of water during and after flooding may increase the incidence of insect- and waterborne diseases, such as dengue fever, cholera, and malaria. Exposure to raw sewage and other hazardous materials mixed with floodwaters poses a serious health threat.