Space & Astronomy

The Pacific’s Busy Storm Season

Published 5 min read
By NASA

NASA

Tropical cyclone activity in the Northwest Pacific Basin has been elevated since April 2026, when Sinlaku surged to super typhoon strength and battered Micronesia, Guam, and the Northern Mariana Islands. Twenty-five named storms later, the basin still hummed with activity in late October.

When the EPIC (Earth Polychromatic Imaging Camera) on the DSCOVR (Deep Space Climate Observatory) satellite captured this image (above) on October 29, 2026, Super Typhoon In-fa churned near the Mariana Islands. At the same time, the remnants of Typhoon Champi approached Alaska amid a parade of storms moving across the Bering Sea. In-fa is the fifth typhoon to affect the Mariana Islands this year.

The MODIS (Moderate Resolution Imaging Spectroradiometer) on NASA’s Terra satellite captured the image of In-fa below on October 30, when the storm was just west of the island chain. In-fa was unusually intense at the time of the image, with a nearly circular shape and large eye—a collection of characteristics that meteorologists use to identify a subset of tropical cyclones known as annular storms. These storms typically lack prominent outer spiral-shaped rainbands—a common feature of standard tropical cyclones—which is why meteorologists have a habit of calling annular storms “doughnuts” or “truck tires.”

Annular storms are rare, accounting for just 4 percent of tropical cyclones in the western North Pacific, according to one analysis. Their eyes average about 45 kilometers (30 miles) in diameter, compared to about 25 kilometers for standard tropical cyclones, and the storms typically maintain their strength longer in unfavorable conditions.

In-fa was still a tropical cyclone when EPIC captured the image at the top of the page, but Champi’s leftovers had gone through the process of extratropical transition and become a whole different type of storm as they entered the Bering Sea’s busy storm track. Tropical cyclones are warm-core storms fueled by the heat and moisture of warm ocean water, but extratropical cyclones typically have cold cores and draw energy from temperature contrasts between warm and cold air masses.

Unlike tropical cyclones, extratropical cyclones typically develop fronts and huge, spiraling cloud bands shaped like commas. “One of the calling cards of extratropical transitions is the expansion of a storm’s wind field,” said Gary Partyka, a meteorologist at NASA’s Goddard Space Flight Center. “It’s not that the winds necessarily grow stronger, but they cover a much larger area,” he said.

In this case, there likely would still have been a midlatitude storm over the Bering Sea, possibly with large, comma-shaped clouds on October 30, even without Champi’s remnants, he added. “But it looks like Champi became intertwined with and helped intensify that system,” he said.

Champi’s transformation came after a long and destructive tour through the West Pacific, during which the typhoon achieved maximum sustained winds of nearly 300 kilometers (185 miles) per hour, prompting some observers to call it one of the strongest storms of the season.

Despite narrowly skirting Taiwan and Guam, the powerhouse storm brought damaging winds and intense rains to both places, as well as to parts of China and Japan. When the remnants hit Alaska, the state avoided catastrophic damage on the scale of what happened after ex-typhoon Halong struck in October 2025, but some areas did see high winds and heavy rain and snowfall, according to news reports.

Champi is the fourth ex-typhoon to enter Alaskan waters this year, noted University of Alaska Fairbanks meteorologist and climatologist Rick Thoman, following Bang-Lang in August, Dujuan in September, and Choi-wan in early October. The autumns of 1997 and 2015—both very strong El Niño years—had three each, he added. Roughly 60 ex-typhoons have impacted the state since 1970, according to Thoman.

Partyka described 2026 as a “particularly active year” for Pacific tropical cyclones, increasing the chances that Alaska would be affected by storms that have gone through extratropical transitions. The strong El Niño underway in the Pacific is a “likely contributor” to the increased activity, he added.

El Niño is a climate pattern that emerges roughly every two to seven years, marked by warmer-than-normal water temperatures in parts of the equatorial Pacific. In the Northwest Pacific, the phenomenon tends to cause storms to more readily curve northward rather than continuing westward to East Asia and Southeast Asia, some experts say, bringing more storms toward Guam, the Northern Mariana Islands, Japan, and the Korean Peninsula.

NASA Earth Observatory images by Michala Garrison, using data from DSCOVR EPIC and MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. Story by Adam Voiland.

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