This article is reprinted from NASA Earth Observatory. Original article here. Edits by EarthSky. As mighty Hurricane Helene pounded the U.S. East in late September 2024, a powerful atmospheric river was sweeping through the Gulf of Alaska, bringing abundant rain to parts of the Pacific Northwest including coastal British Columbia, Canada, and southeastern Alaska. Because of its duration and the concentration of moisture moving across the ocean, experts suspect this atmospheric river was among the most intense to transit the northeast Pacific in a satellite-based record going back to 2000.