Rare 'Cannibal CME' Could Spark Powerful Northern Lights Tonight — NOAA Issues G3/G4 Watches

Major northern lights possible after X‑class flares fuel "cannibal CME" alert

Three coronal mass ejections (CMEs) launched from the Sun on Nov. 9, 10 and 11 are en route to Earth and could merge into a rare, fast-moving “cannibal CME” — a combined cloud that can be larger and faster than any of its individual parts. If conditions line up, the result could be a memorable northern lights display late Tuesday night.

Watches and what they mean

• NOAA's Space Weather Prediction Center has issued a G3 geomagnetic storm watch for Nov. 11 and Nov. 13.
• A G4 watch is in effect for Nov. 12; the geomagnetic G-scale runs from 1 (minor) to 5 (extreme), and G4 is classified as severe.

These CMEs were driven by powerful X‑class flares, including an early‑morning X5.1 flare — the strongest recorded so far in 2025 and the largest since an X9.0 flare on Oct. 3, 2024 that produced a global aurora.

"As always with these events, the intensity of the CME will not be [known] with better certainty until it arrives 1 million miles from Earth and is observed by the solar wind observatories at that location," NOAA's Space Weather Prediction Center said. "It is at that point that any needed Warning decisions can be made by SWPC forecasters. For now, SWPC believes there is potential for G4 levels upon CME arrival and/or as the CME passage progresses."

Aurora potential and the Kp index

Forecasters use the Kp index to estimate auroral reach: higher Kp means more geomagnetic energy and visibility farther south. NOAA's 6 a.m. Kp forecast — which may not have fully accounted for the X5.1 flare — predicted a Kp of roughly 7.3 between about 9 p.m. and midnight Tuesday. If G4 levels materialize, NOAA says auroras could be visible as far south as Alabama and northern California.

"Cannibal CMEs" occur when a later CME overtakes and merges with earlier eruptions, producing a larger, faster cloud that can drive stronger geomagnetic effects. The most recent cannibal CME earlier this year (April 15) produced spectacular auroras visible well south of typical viewing latitudes, including southern France.

Viewing tips and local outlook

Even with a strong CME, aurora visibility depends on the CME's magnetic orientation and on local weather. Clear, dark skies away from city lights are best. In much of Minnesota skies are forecast to be mostly clear this evening, improving the chance of seeing lights; however, northeastern Minnesota — often one of the best viewing areas — may see lingering clouds.

Sunset is early (about 4:48 p.m. locally), so look north from an open, dark spot after roughly 5:30 p.m. Peak activity is forecast around 9 p.m. to midnight, though displays could continue into the early morning hours in some locations.

Forecasters will refine intensity and timing as the CME approaches and as data from solar wind observatories 1 million miles out become available.

Originally reported by Bring Me The News on Nov. 11, 2025. For live updates, follow NOAA's Space Weather Prediction Center.