A major solar flare measuring X9.0 erupted from Active Region 3842 at 12:18 UTC on October 3, 2024. This is now the strongest solar flare of Solar Cycle 25, following X8.7 on May 14, 2024.
A Type II Radio Emission with an estimated velocity of 573 km/s was associated with this event, suggesting a coronal mass ejection (CME) was produced.
Additionally, a Type IV Radio Emission was detected at 12:17 UTC. Type IV emissions occur in association with major eruptions on the Sun and are typically associated with strong coronal mass ejections and solar radiation storms.
Radio frequencies were forecast to be most degraded over parts of Africa and the South Atlantic at the time of the flare.
Due to the location of the source region now in the center of the solar disk, any CME produced by it should be Earth-directed.
Today’s X9.0 comes after X7.1 produced by the same region at 22:20 UTC on October 1 — at the time the second-strongest solar flare of Solar Cycle 25 and now the third.
According to the SWPC, multiple model analyses of the CME associated with the X7.1 flare have been conducted and the analysis indicates that the most likely arrival time will occur on October 4, 2023, though there is a slight chance the CME could arrive late on October 4 or early on October 5.
There is moderate confidence in the timing of the CME’s arrival, but lower confidence in the magnitude and orientation of the arriving Bz component of the magnetic cloud.
A G1 – Minor geomagnetic storm watch has been issued for October 3, to account for the possibility of an early arrival. A G3 – Strong geomagnetic storm watch has been issued for October 4, when the bulk of the plasma is expected to arrive.
Given the strength of the flare, the region’s position, the speed of the CME at around 850 – 950 km/s, and the magnetic complexity of the producing region, a Kp=7 (G3 – Strong geomagnetic storm) is possible during one, possibly two, synoptic periods on October 4.
A G2 – Moderate geomagnetic storm watch has been issued for October 5, for any residual magnetic disturbance that may persist.
Keep in mind, this geomagnetic storm forecast does not include any possible impact from today’s X9.0 flare.
Note: This report is based on preliminary data and is being updated.