NASA Flags Ice Moving Out Of Aniak.

Florida; May 2026: After an extremely chilling winter, thawing happens to be a welcome sight for every inhabitants living in such region; the Alaskans need no special mention. But with melting comes the threat of rapid flooding in low-lying areas as river ice breaks up and periodically jams.

The landscape along the Kuskokwim River appeared frozen in a Landsat 9 image acquired on April 21, 2026 (left). According to observations published by the Alaska-Pacific River Forecast Center, river ice near the town of Aniak was thick and still covered in deep snow as of April 16. The Kuskokwim ice road connecting numerous villages traces a dark line down the river. The thick river ice supported a route that extended about 350 miles (560 kilometres) in winter 2025-2026 and shut down for the season on April 10, according to news reports.

Conditions were changing quickly around May 07th, when the right image was acquired. The previous day, the front of the ice breakup had nearly reached Aniak, and a sheet of grounded ice caused a jam that stretched 21 miles (34 kilometres) upstream. News reports showed ice chunks several feet thick piled up on riverbanks around the town. Ice became unstuck by May 7, and the backup, visible above (right), had started to flow downstream.

2026 Spring Breakup Outlook for Alaska dated 21st April 2026 –

This Breakup Outlook continues to be refined to include more detailed flood potential and

breakup timing information, including graphics and tables with community-specific flood risk and

forecast breakup dates. Snowpack and ice conditions remain largely unchanged from the

previous outlook.

The most notable change is in the spring temperature outlook, which now favors above-average

temperatures through early May. Despite this shift toward warmer conditions, the spring transition has been relatively delayed so far, with cooler than normal conditions persisting longer than typical across much of the region. This delay is helping maintain ice cover for now, but it also sets the stage for a potentially more rapid transition once sustained warming occurs. Overall, this combination continues to increase the likelihood of a more dynamic breakup.

Statewide Flood Potential Overview: The breakup flooding potential is above average across parts of mainland Alaska. In the Interior, the primary areas of concern are the upper Yukon and lower Tanana Rivers, along with the middle Kuskokwim River near Crooked Creek and Aniak/Kalskag. Portions of the middle and lower Yukon, lower Kuskokwim, and the North Slope also face an elevated risk. This increased threat is driven by a combination of above-average snowpack, average to above-average ice thickness, high freeze-up levels, rough ice or freeze-up ice jams reported in several Interior locations, and the potential for delayed snowmelt from below-average April temperatures. In contrast, the Koyukuk, Kobuk, and upper Kuskokwim rivers, as well as rivers across Southcentral Alaska, have a lower breakup flood threat due to below-average snowpack.

Communities are encouraged to review their flood response plans and preparedness actions in

advance of breakup. Beyond main river ice effects during breakup, snowmelt flooding in small channels and ponding on frozen ground during warm days is possible. Ice may block these channels, causing rapid rises, strong currents, and localized flooding. Use caution when traveling off main rivers and

stay aware of recent weather and river conditions.

Ice on the Kuskokwim River remains largely solid, but signs of change are beginning to emerge. Near Nikolai on the upper Kuskokwim, river ice has been reported to be lifting, indicating an increase in surface discharge. Farther downstream, a freeze-up ice jam occurred just below Crooked Creek this past winter, similar to conditions that preceded the record flooding in 2011. In addition, stretches of very rough, broken ice have been observed between Aniak and Bethel. Based on these observations the likelihood of ice jam formation is increased and the risk of flooding is elevated during spring break up.

Thawing degree days (TDD) are used to measure the accumulation of warmth over time. As TDDs increase in spring, they reflect the progressive melting of snowpack and weakening of river ice. The current TDD map points to a notably delayed spring warm-up over much of Alaska. Across most of the Southwest and Interior Alaska, values generally range from about 0%–40% of normal, suggesting below-normal thaw progression and a slower weakening of ice cover. These conditions continue to favour a later breakup timing, though conditions could still shift quickly with sustained warming.

Aniak remained at risk, however, as ice clogged the river later that night, this time several miles downstream from the community. Waters began to rise, and a flood watch was issued for the town on May 8. Water inundated low-lying areas and encroached on homes and businesses near the east side of the runway, according to reports, before receding two days later.

Flooding caused by spring breakup can be most hazardous when heavy snowpack and thick ice remain in place from the winter and there’s a sudden transition from freezing to warmer temperatures. In what is known as a dynamic breakup, snowmelt encounters intact ice and causes water to back up quickly. On the other hand, if ice weakens before significant snowmelt or ice from upstream arrives, jams are less likely to form.

Forecasters noted that spring 2026 showed warning signs of a dynamic breakup. Snowpack was above average in some major river drainages, and historically low temperatures marked the winter and spring months in many places. For example, the March average temperature in Bethel, downstream of Aniak, was 14 degrees Fahrenheit (8 degrees Celsius) below normal. However, floods had been relatively minor along the large rivers through early May, experts noted, while cautioning that more severe flooding still has the potential to develop quickly.

Team Maverick.