Mexico: Adverse weather conditions forecast to continue across much of the country through at least Sept. 10 /update 1

Adverse weather is forecast to continue across much of Mexico through at least Sept. 10. A combination of meteorological factors are expected to generate heavy rainfall and thunderstorms across many parts of the country over the coming days. Strong wind gusts, lightning, and hail are possible during storms. A cold front moving over the Gulf of Mexico will interact with a tropical wave and associated low-pressure area with a potential for cyclonic development to bring thunderstorms and heavy rainfall to central, eastern, northeastern, southern, and southeastern regions. The cold air mass associated with the weather front will generate a surge of cold winds known as a Norte event, which will bring rough seas and may cause waterspouts to form off eastern coastal areas. The North American monsoon will continue to bring showers and storms to northwestern regions and another low-pressure area with a potential for cyclonic development is expected to form off the coast of Oaxaca Sept. 9, bringing extremely heavy rainfall to parts of Chiapas, Guerrero, and Oaxaca. Low-pressure channels over northern and western Mexico are expected to generate showers and storms in these regions over the coming days.

Rainfall totals of over 25 cm (10 inches) are possible in parts of Chiapas, Oaxaca, Puebla, Tabasco, and Veracruz states Sept. 8. Totals of 15-25 cm (6-10 inches) are expected over parts of Chiapas, Oaxaca, Puebla, Tabasco, and Veracruz Sept. 7 and Sept. 9, Hidalgo, San Luis Potosi, and Tamaulipas Sept. 8-9, and Campeche Sept. 8. Rainfall totals of 5-15 (2-6 inches) are forecast across many other parts of the country over the coming days. Winds gusting up to 100 kph (62 mph) and waves up to 4 meters (13 feet) are expected in parts of Veracruz and Tamaulipas along the Gulf of Mexico coast. High temperatures are expected to persist over northwestern regions, with highs of over 45 C (113 F) possible in Baja California Sept. 6-9.

Sustained heavy rainfall could trigger flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed stormwater drainage systems. Sites downstream from large reservoirs or rivers may be subject to flash flooding after relatively short periods of intense rainfall. Landslides are possible in hilly or mountainous areas, especially where heavy rain has saturated the soil.

The severe weather could contribute to transport disruptions throughout affected regions. Floodwaters and debris flows may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around affected areas. Ponding on road surfaces could cause hazardous driving conditions on regional highways. Authorities could temporarily close some low-lying routes that become inundated by floodwaters.

Severe weather may also trigger flight delays and cancellations at airports across the affected region. Authorities may temporarily suspend port operations if strong winds trigger hazardous sea conditions, impacting freight and passenger maritime traffic. Flooding could block regional rail lines; freight and passenger train delays and cancellations are likely in areas with heavy rainfall and potential track inundation.