Weather tracker: Indonesia floods cause landslides and disruption to transport

Heavy rainfall linked to low-pressure system hits south of Java with flood depths of up to 80cm in Semarang

Semarang, the provincial capital of Central Java in Indonesia, experienced severe flooding overnight on Wednesday. This rainfall was linked to a low-pressure system to the south of Java, which brought close to 200mm of rainfall to the area by Thursday daytime. Further rainfall is forecast over the coming week.

Flood depths of up to 80cm have been reported in the old town, with many roads and one railway station closed. There have been 10 reported landslides, and the authorities have advised people who live under clifftops and close to riverbanks to evacuate the area.

The mayor of the city issued a statement saying the rainfall, and consequent flooding, was not expected. Similar flooding has been reported in the past, with flood depths of up to 70cm recorded in November 2023, and again earlier that year. It has been suggested that poor drainage in the city is responsible for such severe flooding, with past cases having been linked to rubbish blocking waterways as well as damaged or breached embankments.

Some city planners have suggested that construction alongside intertidal zones, mangrove deforestation and land subsidence through groundwater extraction activities are also to blame.

In the US, baseball-sized hail was reported on Wednesday night across some of the midwestern states. The National Weather Service (NWS) issued a thunderstorm warning for 38 counties from eastern Kansas to central Missouri.

A hailstone of 10cm was found in the town of Wabaunsee, and another of 7.6cm was found in Geary County. Hailstones of this size can cause severe damage to crops and infrastructure, and can be fatal if they hit someone’s head.

Additionally, strong winds of about 60mph accompanied this storm, and a few tornadoes were reported to have developed between the Kansas towns of Dwight and Alta Vista, according to the NWS.

More unusual weather was seen in southern China this week. The combination of high temperatures reaching about 30C, alongside 100% humidity, led to severe condensation both outside and inside people’s homes. As well as providing highly unpleasant conditions for many, this humidity led to slippery surfaces across southern China and dense fog developed in Hong Kong, which severely reduced visibility.

Cover photo: A flooded street after heavy rain in Semarang, Central Java, Indonesia. Photograph: Xinhua/Rex/Shutterstock