NOAA forecasts moderate geomagnetic storm that could bring auroras to northern U.S.

A solar flare classified as M6.9 erupted on Tuesday, Aug. 25, from sunspot 4513 and was accompanied by a coronal mass ejection (CME). NOAA's Space Weather Prediction Center now projects that the CME, combined with a high-speed solar-wind stream, could produce isolated G1 (minor) to G2 (moderate) geomagnetic storm conditions on Aug. 27 and Aug. 28. The agency estimates the Kp index could reach 5.67, which falls within the G2 range.

"If the Northern Lights are visible, it will be during nighttime hours," NOAA warned.

Under a G2 storm, auroras have previously been observed as far south as New York and Idaho, roughly 55 degrees geomagnetic latitude. The most likely viewing areas include Alaska, Canada, and the northern tier of the contiguous United States—states such as Washington, Idaho, Montana, North Dakota, Minnesota, Michigan, and possibly northern New England. Clear, dark skies away from light pollution will be needed, and at lower latitudes any display may appear as a faint glow near the northern horizon.

Space.com notes that the CME is expected to make only a glancing encounter with Earth, but the simultaneous arrival of the high-speed solar-wind stream could amplify geomagnetic activity, improving aurora visibility prospects.