Thai downpours shift north-westwards after Bangkok declared a disaster zone

Bangkok was declared a disaster zone by its city officials towards the end of last week, after streets in Thailand’s capital city were submerged in up to waist-high flood water. The flooding stemmed from an active cell of low pressure across 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 then sitting over central Thailand by Friday morning. For most of the following two days this low pressure remained roughly in situ, which allowed unrelenting downpours over Bangkok and nearby areas. One weather station near Prachin Buri, just north-east of the capital, recorded 213.5mm within a 24-hour period between Friday and Saturday evening local time – for comparison, London receives an average 585mm a year). Fortunately, the centre of the low-pressure cell shifted north-westwards on Sunday and brought an end to the torrential rainfall.Out in the central Pacific, meanwhile, 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 85-90knots (98-104mph), situated at its closest to the archipelago at approximately 145 miles (233km) south of the Big Island. Strong winds were not the only threat to the Big Island, as the vast quantity of rainfall raised concerns over flooding and mudslides. Since the impacts of Nolo started late on Tuesday 22 September, weather stations in the north-east of the island have received over 530mm of rainfall. Fortunately, Nolo has propagated westwards away from Hawaii where it is forecast to peak in its intensity on Monday 28 September, with current predictions of achieving category 4 status.skip past newsletter promotionafter newsletter promotionMeanwhile, farther east in the Pacific Ocean, Hurricane Polo is now forecast to make landfall with the Baja California peninsula late in the day on Monday 28 September. The once category 5 hurricane will 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 where winds are onshore. Polo will also bring intense downpours while traversing the peninsula with 100-200mm expected, potentially reaching up to 250mm locally. The bulk of this rain falling within a 12-hour period and 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.