Texas was hit by catastrophic flash floods on Friday after powerful thunderstorms unleashed torrential rainfall across the region. Kerr County, in the south-central Hill Country, received more than 300mm of rain in just a few hours.
As of Sunday evening, at least 68 people had been confirmed dead, and 28 girls were missing after flood waters tore through a summer camp.
In just two hours, the Guadalupe River surged by more than 6 metres (20ft), sweeping away vehicles and inundating homes.
The storms were supercharged by moisture from the remnants of Tropical Storm Barry, which had struck Mexico earlier in the week and drawn saturated air from the Gulf, and instability in the atmosphere facilitated by a low-level jet stream. Climate change is expected to increase the likelihood of these events, as warmer air can hold more moisture.
The Hill Country’s rugged topography, marked by steep hills, canyons, and valleys, amplifies the risk and impact of flash flooding, and it is often referred to as “Flash Flood Alley”. On top of that, the area’s limestone and granite terrain exacerbates runoff, because water struggles to soak into the ground.
Meanwhile, what began as a tropical depression near the north-west of the Philippines rapidly intensified into Typhoon Danas over the weekend and struck Taiwan on Sunday morning with winds reaching 85mph and torrential rain. Almost 3,000 people had to evacuate their homes.
Originally expected to head towards Thailand, the storm altered its course over the weekend, veering northwards across the Taiwan strait. On Sunday, more than 150mm of rainfall was recorded in parts of Taiwan, causing landslides and flash flooding. Further heavy rainfall hit the region on Monday morning.
Typhoon Danas is projected to continue its path north-east across the South China Sea, hitting south-east China by midweek. Yellow weather warnings have been issued in Fujian and southern Zhejiang provinces, where wind speeds may reach up to 90mph and more than 130mm of rainfall is expected by Wednesday. However, the exact trajectory of the storm remains uncertain and may shift in the coming days.
Although Thailand was spared a direct hit, the typhoon has amplified the region’s monsoon, intensifying the south-westerly winds and drawing in more saturated air from the surrounding ocean. Consequently, northern Thailand has seen an increased humidity and widespread heavy rainfall, which is expected to reach over 90mm in 24 hours in places, bringing the risk of flash flooding and landslides to 33 provinces, particularly near the Mekong River.
