Madagascar: Adverse weather forecast across much of the country through at least March 7

Severe weather is forecast across much of Madagascar through at least March 7. A tropical disturbance moved over far northern Madagascar early March 4 and is expected to bring heavy rainfall and thunderstorms to northern and eastern regions March 4 and across the northern half of Madagascar March 5 as it moves generally southwestward over the Mozambique Channel. The system is expected to strengthen into a tropical depression and then a tropical storm March 5-6, before curving southward and then southeastward off the southwest coast of Madagascar March 6-7 and likely bringing further adverse weather to southern regions. Storms may be accompanied by strong wind gusts and lightning. Rough seas are also expected in coastal areas. The heaviest rainfall March 4 is expected in north-central and eastern parts of the island; rainfall totals of 4-10 cm (1.6-3.9 inches) are expected across the affected areas. Heavy downpours may trigger flooding in low-lying areas and landslides on unstable slopes.

As of March 4, the Madagascar General Directorate of Meteorology has issued the following warnings:

• Red strong wind warnings (the middle level on a three-tier scale): Along the northeastern and northern parts of the eastern coastlines.

• Red heavy swell warnings: Along the northeastern coastline.

• Yellow heavy rain warnings: Across Alaotra-Mangoro, Analanjirofo, Atsinanana, Betsiboka, Boeny, Fitovinany, Melaky, Sofia, and Vatovavy regions.

• Yellow strong wind warnings: Parts of the northwestern coastline.

• Yellow heavy swell warnings: Northern parts of the eastern coastline.

• Green heavy swell warnings: Parts of the northwestern coastline.

Authorities will likely issue new alerts or update/rescind existing advisories as weather conditions change over the coming days.

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. Disruptions to electricity and telecommunications services are possible where significant flooding, strong winds, or landslides impact utility networks.

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 could also trigger flight delays and cancellations at airports in the affected regions. Flooding could block regional rail lines; freight and passenger train delays and cancellations are possible in areas with heavy rainfall and potential track inundation.

Localized business disruptions may occur in low-lying areas; some businesses might not operate at full capacity because of flood damage to facilities and some employees' inability to reach work sites.

Flooding could heighten the threat of disease outbreaks. Backflow from drains mixed with floodwaters can become trapped in open areas when inundations recede. These stagnant pools often become breeding grounds for mosquitoes and bacteria, increasing the incidence of insect- and water-borne diseases. Exposure to contaminated water from inundated industrial sites, sewer systems, and septic tanks also poses a significant health threat.