Tropical cyclone activity in the Northwest Pacific has been elevated since April 2026. By late October, the basin had recorded 25 named storms, including Super Typhoon In-fa and Typhoon Champi, whose remnants moved toward Alaska after becoming an extratropical storm.

Satellite images captured In-fa near the Mariana Islands on October 29 and 30. The storm had a nearly circular shape and an unusually large eye, features associated with annular storms. These systems usually have few prominent outer rainbands, giving them a doughnut-like appearance. An analysis cited in the report found that annular storms make up about 4 percent of tropical cyclones in the western North Pacific. Their eyes average around 45 kilometers across, compared with about 25 kilometers for typical tropical cyclones.

In-fa was the fifth typhoon to affect the Mariana Islands this year. It was still a tropical cyclone when the October 29 image was taken. Champi, meanwhile, had undergone an extratropical transition as its remnants entered the Bering Sea storm track.

Tropical cyclones draw energy from warm ocean water and have warm cores. Extratropical cyclones generally have cold cores and draw energy from temperature differences between air masses. They can also develop fronts and broad, comma-shaped cloud bands. NASA meteorologist Gary Partyka said that during an extratropical transition, a storm’s winds can cover a much larger area, even if they do not necessarily become stronger.

A midlatitude storm likely would have been present over the Bering Sea on October 30 even without Champi’s remnants, Partyka said, but Champi appears to have become intertwined with and helped intensify the system.

Before reaching Alaska, Champi had traveled through the western Pacific with maximum sustained winds of nearly 300 kilometers per hour. It brought damaging winds and heavy rain to Taiwan and Guam, despite narrowly missing both, as well as to parts of China and Japan. Alaska avoided catastrophic damage comparable to that caused by ex-typhoon Halong in October 2025, although some areas experienced high winds and heavy rain and snow, according to news reports.

Champi was the fourth ex-typhoon to enter Alaskan waters in 2026, following Bang-Lang in August, Dujuan in September, and Choi-wan in early October, according to University of Alaska Fairbanks meteorologist and climatologist Rick Thoman. He noted that the autumns of 1997 and 2015, both strong El Niño years, each saw three ex-typhoons enter Alaskan waters. Since 1970, roughly 60 ex-typhoons have affected the state, he said.

Partyka described 2026 as a particularly active year for Pacific tropical cyclones and said the strong El Niño underway was a likely contributor. In the Northwest Pacific, El Niño can make storms more likely to curve northward rather than continue west toward East and Southeast Asia, bringing more storms toward Guam, the Northern Mariana Islands, Japan, and the Korean Peninsula.

Sources: NASA Breaking News.