This story has been updated.

Three tropical cyclones — Linfa, Chan-hom and Ningka — are churning across the Pacific Ocean toward Asia this week in a recent spike of typhoon activity in the region. The massive Typhoon Chan-hom will prove to be the most destructive of the three as it nears China’s most populous city of Shanghai over the next 48 hours.

Typhoon Chan-hom

Typhoon Chan-hom is the middle of the three cyclones and by far the largest, currently tracking through the islands of Japan’s far southern Okinawa prefecture. Peak wind gusts in Okinawa have topped 100 mph, and Japan’s NHK reports that 16 people have been injured in Miyako-jima.

Over the past two days, Chan-hom’s wind field has nearly doubled, and now covers over 136,000 square miles in the western Pacific Ocean. On Thursday morning, the typhoon was the equivalent of a category 2 hurricane, with sustained wind speeds of 105 mph, and wind gusts to 125 mph.

But Typhoon Chan-hom is forecast to intensify even more as it moves through very warm ocean water and edges closer to China, potentially reaching category 4 status with sustained winds of 135 mph a mere 100 miles offshore on Friday night, local time.

Upper-level steering winds will take the center of the typhoon precariously close to northern Taiwan. Given the storm’s massive size, rainfall will undoubtedly be heavy and prolonged in Taiwan with strong wind gusts as the typhoon sweeps to the north. Taiwan is already seeing Chan-hom’s outer cloud field on Thursday, and conditions there — particularly in the capital Taipei on the north coast — will continue to deteriorate over the next 24 hours. Chan-hom is expected to be at its strongest when it’s closest to Taipei on Friday, though at this time it’s not expected to strike Taiwan directly.

There’s still a lot of uncertainty in Chan-hom’s track beyond Friday, says the Joint Typhoon Warning Center. But as of Thursday morning, the typhoon is forecast to make landfall on the China coast near the city of Taizhou on Saturday morning (local time) as a Category 3 with winds of 120 mph.

As Chan-hom makes landfall, the storm surge in areas north of the eye could prove severe for coastal areas north of the eye, including China’s low-lying, most populous city Shanghai, home to roughly 24 million people. Shanghai is only around six feet above sea level, but as Weather Underground’s Jeff Masters pointed out on Tuesday, China has been taken precaution to protect the economically critical hub.

“According to 2011 New York Times article, engineers have stretched hundreds of miles of levees along the Yangtze River where it meets the sea in the city,” Masters wrote. “The lowest of those levees were built to withstand a one-in-1,000-year storm surge, and defended Shanghai against the highest tidal surge in modern times, which came during Typhoon Winnie of 1997.”

Whether or not the typhoon makes direct landfall the rain will be torrential, especially in the mountainous areas near the coast. The HWRF model, specialized for hurricane forecasts, is suggesting rainfall totals will exceed 15 inches in some locations near the coast, just south of Shanghai.

Tropical Storm Linfa

Tropical Storm Linfa is farthest west of the three cyclones, having made landfall in China northeast of Hong Kong on Thursday evening, local time. Over the past 24 hours, Linfa defied forecasts and strengthened into a Category 1 typhoon in the warm waters of the South China Sea.

The China Meteorological Administraton issued a tropical cyclone warning for the combined impacts of Linfa and Typhoon Chan-hom on Thursday morning, local time.

This is the second landfall for Linfa — it already came ashore once in the mountainous terrain of Luzon in the Philippines on Sunday morning, Philippines time. Linfa’s heavy rains caused flooding in Luzon as far south as Manila — over 200 miles away from where the storm center made landfall — and it’s broad circulation continues to draw rain bands over Luzon on Tuesday. Linfa seems likely to be a rainmaker for the region around Hong Kong. Linfa’s rain bands have already reached southeast China on Tuesday.

Typhoon Nangka

Typhoon Nangka is not the largest in size or the closest to land, but it remains the strongest cyclone in the Pacific on Thursday, with sustained winds of 155 mph — a Category 4 on the Saffir-Simpson scale.

Fortunately, Nangka is not tracking toward land this week, though the storm is going to move into very warm ocean waters as it churns northwest. Forecast models suggest that Nangka is something to watch for southern Japan late next week, though it’s too soon to say exactly how the powerful storm might interact with land at that point.