India: Adverse weather forecast to continue across northeastern regions through at least June 22 /update 1

Severe weather is forecast to continue across northeastern India through at least June 22. Heavy rainfall and thunderstorms have been ongoing over the region in recent days, and the Indian Meteorological Department (IMD) has issued a press release warning of further heavy rainfall accompanied by thunderstorms, lightning, and strong winds over the coming days. Disruptions are impacting parts of the region due to flooding and landslides amid the recent heavy rainfall. In Sikkim State, landslides have killed at least six people in Mangan District and affected more than 3,000 people across the state, dozens of whom have been housed in emergency shelters. Floods and landslides have also damaged at least 52 homes and several roads, including sections of the National Highway 10. Authorities have begun evacuating around 1,200 tourists stranded by the severe weather in the Lachung area. More than 100,000 people have also been affected across Assam State due to flooding caused by overflowing rivers, with Karimganj District the worst affected. Further adverse weather over the coming days will likely exacerbate the situation and hamper ongoing response and recovery efforts.

The IMD has issued the following severe weather warnings across the affected area June 18-22:

• Red heavy rainfall, thunderstorm, and lightning warnings (the middle level on a three-tier scale): Arunachal Pradesh, Assam, Meghalaya, Sikkim, and Sub-Himalayan West Bengal June 18-19.

• Yellow heavy rainfall, thunderstorm, and lightning warnings: Manipur, Mizoram, Nagaland, and Tripura June 18-19, Assam, Meghalaya, Sikkim, and Sub-Himalayan West Bengal June 20-22, and Arunachal Pradesh June 20.

• Yellow rainfall, thunderstorm, and lightning warnings: Arunachal Pradesh June 21-22 and Manipur, Mizoram, Nagaland, and Tripura June 22.

Officials could update and extend the coverage of weather alerts 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.

Authorities could issue mandatory evacuation orders for flood-prone communities over the coming days. Disruptions to electricity and telecommunications services are possible where significant flooding 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 regional airports.

Localized business disruptions may occur in low-lying areas; some businesses might not operate at full capacity because of flood damage to facilities, possible evacuations, 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 a breeding ground 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.