Indonesia: Adverse weather forecast nationwide through at least July 31

Event

Thunderstorms, heavy rains, strong winds, and possible flooding are forecast across much of Indonesia through at least July 31. As of July 29, 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 July 29-31. Yellow thunderstorm, strong winds, flood, and heavy rain warnings have been issued across much of the rest of Indonesia during the same period. Authorities will likely issue new alerts or update/rescind existing advisories as weather conditions change over the coming days.

Disruptions due to flooding are ongoing in Parigi Moutong Regency in Central Sulawesi Province as of July 29. Heavy rainfall late July 28 triggered flooding in Torue District which inundated homes in several villages. Authorities have reported three fatalities and four others are missing. Around 450 homes have been impacted and 11 have been seriously damaged. Approximately 18,000 people were affected by the flooding and 450 fled to several evacuation points. The adverse weather has caused disruptions to road traffic in and around the affected area.

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