The winter of 2026 came to a dramatic end in southern Alaska. Coastal areas experienced cooler than average temperatures and periods of moderate to heavy snow. From above, a noticeable cloud formation spread over the nearby ocean, revealing just how unstable the atmospheric conditions were.
On March 19, 2026, the last day of astronomical winter, a NASA satellite captured a remarkable image of the spectacle. NOAA’s weather briefing described a combination of low pressure over the Gulf of Alaska and high pressure across eastern Russia and northern Alaska. This pattern pushed frigid Arctic air southeast over the Alaska Peninsula.
How cloud towns are formed on the sea
As this cold, dry air flowed over the relatively warm waters of the bay, the bay began to change. The result was the formation of “cloud streets,” long, parallel bands of clouds aligned with the wind. These features develop when the air receives heat and moisture from the ocean surface. Rising pockets of warm, moist air form clouds, and cold air sinks between them, leaving distinct gaps.
As we approached the coast, the sky remained mostly clear as the air had not yet absorbed enough heat and moisture to form clouds. (Note that hazy areas near the coast could be geological formations or sea fog.) Further offshore, the cloud paths became more defined and gradually evolved into open-cell clouds. These formations look like a thin wall of clouds surrounding a circular space in the sky.
swirl and island effect
Another eye-catching pattern appeared near Unimak Island, the easternmost tip of the Aleutian Islands. On the leeward side of the island, the satellite detected a Von Karman vortex street that appears to repeat spirals rotating in opposite directions. These patterns form when strong winds blow around high ground, such as an island that rises out of the ocean.
Achieve powerful polar low spin offshore
One of the most dramatic features in the image was a large swirling cloud system about 180 miles (300 kilometers) southwest of Anchorage. Meteorologist Matthew Capucci identified it as a polar cyclone, a compact storm that develops when cold polar air moves over warm water. In this case, the system reached tropical storm-force winds and produced snow and even thunderstorms near its center.
The cold and stormy months continue
The remarkable situation seen on March 19th was part of a broader pattern. Alaska experienced continued cold weather and repeated storms throughout the month. Although temperatures began to warm by late April, the report said conditions will remain unstable and wet in southcentral and southeastern Alaska as the atmospheric river approaches.
NASA Earth Observatory image by Michala Garrison using NASA EOSDIS LANCE and MODIS data from GIBS/Worldview.
