Auroras could be visible in more states with forecast 'strong' geomagnetic storm

Northern lights could be seen farther south than usual with the expected arrival of three coronal mass ejections, according to the National Oceanic and Atmospheric Administration's Space Weather Prediction Center.

A Coronal Mass Ejection (CME) is a massive burst of solar material and magnetic field from the sun's corona. Auroras occur when the solar material interacts with the atoms and molecules in Earth's atmosphere.

The Space Weather Prediction Center is forecasting the arrival of three coronal mass ejections around mid-afternoon ET on Thursday.

The CMEs left the sun on June 2, and a combination event -- in which they arrive to Earth's atmosphere at the same time -- is likely because the last of the three CMEs, the fastest, is expected to catch up and combine with the first two.

Forecasters are confident about the CMEs arriving to Earth, but intensity is still uncertain due to the complex nature of the CMEs, NOAA said.

Geomagnetic storms at level G3, or "strong," are expected into the evening and possibly overnight into Friday, according to NOAA. This level of geomagnetic storms could have minor effects to some technological infrastructure.

A G3 storm could require voltage corrections on power systems and cause intermittent satellite navigation and low-frequency radio navigation problems, according to NOAA.

Auroras could be visible over many northern states and from Illinois to Oregon, the forecast shows.

There is a chance that G4, or "severe," levels are possible, especially if the CMEs are more Earth-directed than the modeling suggests. G4 storms can cause possible widespread voltage problems and could disrupt satellite navigation and low-frequency radio navigation. Spacecraft could also experience surface charging and tracking problems.

Northern lights have been seen as far south as Alabama and Northern California under G4 geomagnetic storm conditions.

The best time to see the northern lights in the U.S. is generally between 10 p.m. and 4 a.m. local time, and traveling to the darkest location possible is recommended for the best viewing, according to NOAA.