The national weather service said zones south of Oaxaca and off Veracruz each had a 90 percent chance of cyclone development within 48 hours. Veracruz was forecast to see 150 to 250 millimetres of rain.
Mexico's national weather service said on Tuesday that two low-pressure zones each had a 90 percent chance of becoming a cyclone within 48 hours and within seven days. Publimetro reported the forecast. One zone was about 400 kilometres south-southwest of Puerto Angel, Oaxaca, moving slowly west-northwest. The other was in the Gulf of Mexico off Veracruz.
The heaviest rain risk was in Veracruz, with torrential falls of 150 to 250 millimetres expected mainly in the north and centre. Intense rain of 75 to 150 millimetres was forecast for southeast Tamaulipas, southeast Guerrero, parts of Oaxaca and Chiapas, and south and west Tabasco.
Very heavy rain was forecast for Michoacan, the State of Mexico, Puebla and Morelos, and heavy rain for Mexico City and other central, western, northeastern, eastern and southeastern states. The service said storms could bring lightning, hail, flooding and standing water.
Authorities were keeping watch on both systems. Publimetro did not report that either zone had been named as a tropical storm on Tuesday.
The next forecast step is whether either system reaches cyclone strength inside the 48-hour window the weather service gave.