G3 – Strong geomagnetic storm following CME impact produced by X1.3 solar flare

The coronal mass ejection (CME) produced by the X1.3 solar flare on August 14, 2024, impacted Earth at approximately 14:30 UTC on August 17, producing a brief period of G3 – Strong geomagnetic storming.

A Geomagnetic K-index of 5 (G1 – Minor geomagnetic storm) threshold was reached at 16:17 UTC, followed by a K-index of 6 (G2 – Moderate) at 17:12 UTC.

The G3 – Strong geomagnetic storm (K-index of 7) threshold was reached at 17:46 UTC.

A strong geomagnetic storm is a large disturbance in Earth’s magnetic field. It often varies in intensity between lower levels and strong storm conditions over the course of hours during the duration of the effect, NOAA SWPC forecasters said, adding that infrastructure operators have been notified to mitigate any possible impacts.

G3 – Strong geomagnetic storm is anticipated to impact areas primarily poleward of 50 degrees geomagnetic latitude. This storm could cause voltage irregularities in power systems, potentially triggering false alarms in some protection devices.

Spacecraft in low Earth orbit might experience surface charging and increased atmospheric drag, which could lead to orientation issues. Satellite navigation systems, including GPS, may encounter intermittent problems such as loss-of-lock and increased range errors, impacting positioning accuracy. High-frequency radio communications may also be disrupted.

Additionally, the aurora borealis could be visible as far south as Pennsylvania, Iowa, and Oregon, offering a rare viewing opportunity in these regions.

The strength of the impact was relatively unexpected as this was a weak-looking CME. However, taking into account the state of Earth’s magnetic field and other factors, it might not be that surprising.

Solar activity was at moderate levels over the past 36 hours, with 3 M-class flares – M1.3 at 13:24 UTC on August 16, M1.6 at 10:33 UTC on August 17, and M1.1 at 11:44 UTC on August 17.

There’s a 70% chance of M-class solar flares through August 19 and 20% of X-class.

Featured image credit: Thomas Jorgenson via SpaceWeather