A pedestrian holds an inverted umbrella against strong winds during heavy rain from Typhoon Noul, in Hong Kong, Sunday. Reuters-Yonhap

HONG KONG — Typhoon Noul will bring heavy to torrential rain across much of southern China for the next two days, authorities said, after sweeping through Guangdong province and neighboring Hong Kong with gale-force winds following its landfall on Sunday.

China issued its highest-level alert for flash floods in several provinces after the year's strongest typhoon forced the relocation of more than 700,000 people in Guangdong, authorities said.

The Ministry of Water Resources and the China Meteorological Administration jointly issued a red warning for flash floods. From Sunday evening through Monday evening, flash floods are expected in parts of Jiangxi, Hunan, Guangdong, Sichuan, Shaanxi, Gansu and southeastern Xinjiang.

Authorities warned residents to "pay attention to real-time monitoring, flood warning, and evacuation and risk avoidance prevention."