Indonesia: Adverse weather forecast nationwide through at least Sept. 9

Event

Thunderstorms, heavy rains, strong winds, and possible flooding are forecast across much of Indonesia through at least Sept. 9. As of Sept. 7, the Indonesian Agency for Meteorology, Climatology, and Geophysics (BMKG) has issued orange (middle-level on a three-tier scale) flood warnings for Central Sulawesi Province Sept. 7-9, Central Kalimantan Province Sept. 7-8, and West Kalimantan Province Sept. 8. Yellow thunderstorm, strong winds, and heavy rain warnings have been issued across much of the rest of Indonesia Sept. 7-9. Authorities will likely issue new alerts or update/rescind existing advisories as weather conditions change over the coming days.

Disruptions due to adverse weather conditions are ongoing in several parts of Indonesia as of Sept. 7. Heavy rainfall in Cianjur Regency in West Java Province Sept. 6-7 triggered flooding and landslides in the region. Over 100 homes have been affected by flooding and at least 21 have been damaged by landslides. An unconfirmed number of people have been evacuated due to the threats to their homes and at least two roads in the regency have been blocked by landslides. Around 40 homes in Gorontalo Regency in Gorontalo Province were flooded following heavy rainfall Sept. 5. The floods have affected more than 150 people in the Tibawa district of the regency. Flooding also affected parts of Luwu Regency, South Sulawesi Province, Sept. 5 after a levee burst during heavy rainfall. Around 20 homes across six villages were damaged by the floods. Heavy rainfall in Sidenreng Rappang Regency in South Sulawesi Province Sept. 4 triggered flooding and landslides. Nearly 900 people in Pitu Riawa District were cut off after landslides blocked road access to the area. Heavy rainfall Sept. 3-4 triggered flooding in parts of Central Kalimantan Province. Around 3,000 people in Gunung Mas Regency have been affected by flooding and overflowing rivers submerged around 350 homes and other buildings in Central Katingan District. Severe flooding since Sept. 2 in Sintang Regency, West Kalimantan Province, has affected around 35,000 people as of Sept. 5.

Hazardous Conditions
Sustained heavy rainfall could trigger further flooding in low-lying communities near rivers, streams, and creeks. Coastal flooding is also possible during high tides. Urban flooding is also possible in developed areas with easily overwhelmed 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 heavy rainfall has saturated the soil. Power outages could occur throughout the affected area.

Transport
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 also cause hazardous driving conditions on regional highways. Authorities could temporarily close some low-lying routes that become inundated by floodwaters.

The disruptive weather may cause delays and cancellations at regional airports. 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 possible in areas with heavy rainfall and track blockages.

Disruptions triggered by inclement weather and resultant hazards, such as flooding, could persist well after conditions have improved - it could take days before any floodwaters recede and/or officials clear debris. If there is severe damage to infrastructure, repair or reconstruction efforts may result in residual disruptions.

Advice

Seek updated information on weather and related disruptions, including road conditions before driving or routing shipments through areas where severe weather is forecast. Plan accordingly for potential freight delivery delays if routing shipments by truck through the affected area. Do not attempt to drive through flooded areas. Charge battery-powered devices if prolonged electricity outages occur.

Resources

Indonesian Agency for Meteorology, Climatology, and Geophysics
Indonesian Agency for Meteorology, Climatology, and Geophysics (Twitter)
Indonesian National Board for Disaster Management