A “severe” geomagnetic storm and auroral phenomena could occur far across the southern United States on Thursday after charged solar particles crashed into Earth, the National Oceanic and Atmospheric Administration’s Space Weather Prediction Center warned.

The center warned of the approach of an enormous mass of charged solar particles ejected from the sun, and later reported that the coronal mass ejection hit Earth at 11:15 a.m. ET on Thursday. A G4-class “severe” geomagnetic storm remained likely.

The solar flare was classified as a Class X 1.8 solar flare, which is the most powerful type of flare the Sun can emit.

The agency said “storms of this magnitude could disrupt power grids, knock satellites off course, disrupt GPS navigation” and damage critical infrastructure technology.

The agency initially said it would not know the characteristics of the burst until it was a mile from Earth and its speed and magnetic intensity were measured by satellites.

On Thursday, it was confirmed that “the expected coronal mass ejection (CME) arrived on Earth at 11:15 a.m. EDT at a speed of nearly 1.5 million miles per hour.”

According to Noaa, the Northern Lights on Thursday “could become visible across much of the northern half of the country and perhaps even as far south as Alabama to Northern California.”

Coronal mass ejections (CMEs) – a fast-moving clump of plasma – can cause significant disruptions in Earth’s magnetic field. The Sun has an 11-year activity cycle and scientists believe it is nearing its peak when solar flares, CMEs and auroras become more common.

Last year, the Space Weather Prediction Center released a “revised forecast” for the current solar cycle, saying the upcoming solar maximum would occur earlier than previously predicted and would be more explosive than originally predicted.

The Sun’s current cycle, Solar Cycle 25, officially began in early 2019 and is expected to peak next year. However, in an updated forecast, the agency said that “solar activity will increase faster and peak at higher levels” and that the solar maximum is likely to begin between January and October this year.