Space weather alert: A "cannibal" geomagnetic storm—when a fast-moving CME overtakes earlier CMEs—may arrive Wednesday and could amplify the Northern Lights across much of the U.S. Two earlier CMEs already produced a G4-level display Tuesday, and NOAA says a faster, more energetic third wave is expected between Wednesday afternoon and evening. Visibility will depend on the CME’s magnetic alignment with Earth and local cloud cover; with clear skies the aurora could be seen as far south as Florida.
‘Cannibal’ Geomagnetic Storm May Supercharge Northern Lights Across the U.S.
Space weather alert: A "cannibal" geomagnetic storm—when a fast-moving CME overtakes earlier CMEs—may arrive Wednesday and could amplify the Northern Lights across much of the U.S. Two earlier CMEs already produced a G4-level display Tuesday, and NOAA says a faster, more energetic third wave is expected between Wednesday afternoon and evening. Visibility will depend on the CME’s magnetic alignment with Earth and local cloud cover; with clear skies the aurora could be seen as far south as Florida.
07:44 AM, 11/13/2025Science
Space weather experts are warning that a so-called "cannibal" geomagnetic storm may arrive Wednesday and could make the Northern Lights brighter and more widespread across much of the United States. A previous storm produced spectacular auroras Tuesday after reaching G4 intensity, and forecasters say a faster, more energetic third coronal mass ejection (CME) could intensify the show.
What is a geomagnetic storm?
Coronal mass ejections (CMEs) are huge expulsions of magnetized plasma from the Sun’s corona. When charged particles from a CME collide with oxygen and nitrogen in Earth’s upper atmosphere, they excite those atoms and create the shimmering colors known as the aurora borealis (Northern Lights).
What makes a storm "cannibal"?
A "cannibal" storm occurs when a later, faster CME catches up with one or more earlier CMEs. The eruptions pile up and can produce a compounded, more powerful geomagnetic disturbance.
“They all pile up behind each other, so you get this compound effect,” said Dr. Steph Yardley, Vice Chancellor Fellow at Northumbria University.
NOAA’s Space Weather Prediction Center says two CMEs already produced Tuesday’s brilliant display, and a third CME — expected between Wednesday afternoon and evening — appears to be the most energetic and fastest of the three. NOAA issued a warning for geomagnetic activity at G4 or greater through 2:45 p.m. EST Wednesday.
Possible impacts
NOAA uses a five-step G1–G5 scale to rate geomagnetic storms; G5 is the most intense and rare. Strong geomagnetic storms can interfere with precision GPS systems and have the potential to cause disruptions in electrical transmission systems. Space operations can be affected as well: NASA cited unsettled space weather when postponing a scheduled Blue Origin New Glenn launch.
Will Americans see the aurora?
Visibility depends on two key factors beyond storm strength. First, the CME’s magnetic field must align favorably with Earth’s magnetosphere — even powerful CMEs can produce weak auroras if the magnetic orientations don’t match. Second, local weather is decisive: cloud cover will block ground-based viewing regardless of storm intensity.
Observers reported the aurora was visible to the naked eye as far south as Alabama on Tuesday, and camera images from Oklahoma captured vivid displays. With a clear sky and favorable magnetic alignment, experts say the lights could be visible as far south as Florida on Wednesday. Forecasts expect heavy cloud cover across parts of the Pacific Northwest, while the Northeast may have a better chance after storms reduced visibility Tuesday.
Practical tips: Check NOAA Space Weather Prediction Center updates and local sky conditions before heading out. Find a dark location away from city lights and allow your eyes to adjust for the best chance to see the aurora.