Key facts
- Bangkok was declared a disaster zone due to flooding from heavy rainfall.
- Streets in Thailand's capital were submerged in up to waist-high water.
- A low-pressure system caused continuous heavy rainfall and thunderstorms in central Thailand.
- One station near Prachin Buri recorded 213.5mm of rain in 24 hours.
- Hurricane Nolo threatened Hawaii's Big Island with heavy rainfall and potential flooding.
- Hurricane Polo was forecast to make landfall on Mexico's Baja California peninsula as a category 2 storm.
Bangkok was declared a disaster zone towards the end of last week as streets in Thailand's capital were submerged in up to waist-high flood water. The flooding was caused by an active cell of low pressure over central Thailand that brought continuous heavy rainfall and thunderstorms to Bangkok and surrounding regions. The heavy rain began early on Thursday when the weak area of low pressure travelled north-westwards up the Gulf of Thailand before settling over central Thailand by Friday morning. For most of the following two days, this low pressure remained in place, leading to unrelenting downpours over Bangkok and nearby areas. One weather station near Prachin Buri, northeast of the capital, recorded 213.5mm of rainfall within a 24-hour period between Friday and Saturday evening local time. Fortunately, the centre of the low-pressure cell shifted north-westwards on Sunday, bringing an end to the torrential rainfall in Thailand. Meanwhile, in the central Pacific, citizens of Hawaii’s Big Island were threatened by Hurricane Nolo over the weekend. The system initially approached the archipelago early last week, bringing heavy rainfall from around Tuesday evening. By the early hours of Saturday, Nolo was a category 2 hurricane with sustained windspeeds of 85-90 knots (98-104mph), situated approximately 145 miles (233km) south of the Big Island. The vast quantity of rainfall raised concerns over flooding and mudslides. Since the impacts of Nolo started late on Tuesday, September 22, weather stations in the north-east of the island had received over 530mm of rainfall. Nolo has since propagated westwards away from Hawaii and is forecast to peak in intensity on Monday, September 28, potentially achieving category 4 status. Farther east in the Pacific Ocean, Hurricane Polo is now forecast to make landfall with the Baja California peninsula late on Monday, September 28. The once category 5 hurricane is expected to downgrade to category 2 by landfall, with sustained winds of 96-110mph. A hurricane warning has been issued in coastal regions due to the risk of a storm surge. Polo is also expected to bring intense downpours of 100-200mm to the peninsula, potentially reaching up to 250mm locally, with the bulk of this rain falling within a 12-hour period, bringing the risk of life-threatening flooding and mudslides. The storm will continue to weaken while propagating north-eastwards across the Sonora region in Mexico.