Brazil, Peru: Adverse weather forecast across parts of Brazil and Peru through at least Oct. 2

Event

Thunderstorms and heavy rainfall are forecast across parts of western, southern, and northeastern Brazil and central and eastern Peru through at least Oct. 2. Storms may be accompanied by strong wind gusts, lightning, and possible hail. Heavy downpours could trigger flash and urban flooding, as well as landslides on unstable slopes. Snowfall and sleet are also possible in mountainous areas of Peru.

As of early Sept. 30, Brazil's National Institute of Meteorology (Inmet) has issued the follwing warnings across the affected area:

• Orange storm warnings (the middle level on a three-tier scale): across Acre, southwestern Amazonas, western Mato Grosso, northern Mato Grosso do Sul, and Rondonia states. Between 3-6 cm (1-2 inches) of rain per hour or 5-10 cm (2-4 inches) of rain per day and winds of 60-100 kph (37-62 mph) are forecast in these orange warning areas.

• Yellow storm warnings: across parts of southeastern Amapa, Espirito Santo, southern Goias, coastal Maranhao, central Mato Grosso, much of Mato Grosso do Sul, central Minas Gerais, northern Para, western Parana, Rio de Janeiro, western Rio Grande do Sul, far western Santa Catarina, and northern and southern Sao Paulo states.

The National Meteorology and Hydrology Service of Peru (SENAMHI) has issued orange weather warnings (the middle level on a three-tier scale) for precipitation in the mountain region, which runs down the central spine of the country, through Oct. 2 and for rain in the rainforest region in the east through Oct. 1. Snowfall accumulations of up to 3 cm (1.2 inches) are forecast in areas above 4,000 meters (13,123 feet) in the mountain region and precipitation in both regions may be accompanied by strong wind gusts and thunderstorm activity. The heaviest rainfall in the rainforest region is expected Sept. 30, with rainfall accumulations of 4-5 cm (1.6-2 inches) possible. The heaviest rainfall in the mountain region is forecast Oct. 1. with rainfall accumulations of 1-2 cm (0.4-0.8 inches) possible.

Officials could update and possibly extend the coverage of the relevant weather alerts over the coming days.

Hazardous Conditions
The storms will be capable of producing heavy downpours and damaging winds across the affected area. In areas where heavy rainfall occurs, it could trigger flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed or a lack of stormwater drainage systems. Sites located 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 the soil has become saturated by heavy rainfall. Disruptions to electricity and telecommunications services are possible where significant flooding, landslides, or strong winds impact utility networks.

Transport
Floodwaters and debris flows could render some bridges, rail networks, or roadways impassable, impacting overland travel in 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 could also trigger intermittent flight delays and cancellations at airports in the region, though these are unlikely to be severe or prolonged. Flooding could block regional rail lines; freight and passenger train delays and cancellations are possible in areas that see heavy rainfall and track inundation. Localized business disruptions may occur in low-lying areas.

Advice

Monitor local media for weather updates and related advisories. Confirm all transport reservations and business appointments before travel. Make allowances for localized travel delays and potential supply chain disruptions where flooding has been forecast. Do not drive on flooded roads. Charge battery-powered devices in the case of prolonged electricity outages.

Resources

National Institute of Meteorology (Inmet)
National Meteorology and Hydrology Service of Peru (SENAMHI)