Mexico: Adverse weather conditions forecast across much of the country through at least July 20

Adverse weather is forecast across much of Mexico through at least July 20. A combination of meteorological factors, including low-pressure channels, a monsoon trough, and successive tropical waves, are expected to generate heavy rainfall and thunderstorms across many parts of the country over the coming days. Strong wind gusts, lightning, and possible hail are possible during storms. A tropical wave off the south coast of western Mexico will bring heavy rainfall to western regions July 17 and another tropical wave will move across southern regions July 17-19, bringing adverse weather to southern Mexico. A new tropical wave is forecast to approach the Yucatan Peninsula from July 20 and will likely bring further downpours to southeastern regions. The North American Monsoon will bring rainfall and thunderstorms to northwestern regions and low-pressure channels over northern, northeastern, eastern, and southeastern Mexico are expected to generate showers and storms in these regions.

Rainfall totals of 7.5-15 cm (3-6 inches) are forecast across parts of Guerrero and Oaxaca July 17-18, Chiapas July 17, Durango, Jalisco, Michoacan, Nayarit, and Sinaloa July 18, and Chiapas, Oaxaca, and Veracruz July 20. Rainfall totals of 2.5-7.5 (1-3 inches) are forecast across many other parts of the country over the coming days. Strong winds may generate whirlwinds and dust storms in parts of northern Mexico over the coming days. High temperatures are expected to persist over northern regions, with highs of 40-45 C (104-113 F) possible in parts of Baja California, Sinaloa, and Sonora July 17-20.

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.