A growing typhoon is sweeping across the Pacific Ocean toward the Philippines, with forecasters warning it could strengthen into a supertyphoon and press on towards Taiwan, Hong Kong or mainland China later this week.

Typhoon Doksuri began as a tropical storm in the Western Pacific on Sunday morning, according to the United States’ Joint Typhoon Warning Center. By the end of the day, it had been upgraded to a typhoon with maximum winds of 230 kilometers per hour (140 miles per hour), according to Philippines weather agency Pagasa.

That could increase to about 18 inches of rainfall by Wednesday as the typhoon intensifies and heads toward the northern part of the South China Sea – spelling potential trouble for Taiwan, Hong Kong, and parts of southern China.

Doksuri, also known as Egay in the Philippines, could become a supertyphoon by late Tuesday or early Wednesday, Pagasa warned – the equivalent of a Category 5 hurricane, the highest and most destructive level on the scale.

At that level, storms can cause catastrophic damage to residential areas, depending on wind speeds and the extent of coastal storm surges.