Long-duration X1.4 solar flare erupts from old region 3664, partial halo CME produced

x1.4 solar flare may 29 2024 sdo aia 304

A major, long-duration solar flare measuring X1.4 erupted from Active Region 3697 (previously numbered 3664) at 14:37 UTC on May 29, 2024. This is the second X-class solar flare since May 27.

A Type II Radio Emission with an estimated velocity of 878 km/s was associated with the event, suggesting a coronal mass ejection (CME) was produced.

A Type IV Radio Emission was registered at 14:48 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.

In addition, a 10 cm Radio Burst (tenflare) with a peak flux of 300 sfu was registered from 14:21 to 14:24 UTC. A 10cm radio burst indicates that the electromagnetic burst associated with a solar flare at the 10cm wavelength was double or greater than the initial 10cm radio background. This can be indicative of significant radio noise in association with a solar flare. This noise is generally short-lived but can cause interference for sensitive receivers including radar, GPS, and satellite communications.

Radio frequencies were forecast to be most degraded over the Americas, Atlantic Ocean, Europe, and west Africa at the time of the flare.

The flare produced a partial halo CME and initial modeling suggests the presence of a fast, at least a partially Earth-directed component. The arrival is expected by late May 31.

x1.4 solar flare may 29 2024 sdo aia 131 bg
X1.4 solar flare on May 29, 2024. Credit: NASA/SDO AIA 131, Helioviewer, The Watchers
x1.4 solar flare may 29 2024 sdo aia 304 bg
X1.4 solar flare on May 29, 2024. Credit: NASA/SDO AIA 304, Helioviewer, The Watchers
drap x1.4 solar flare may 29 2024
goes-x-ray-flux-1-minute x1.4 solar flare may 29 2024
sunspots on may 29 2024
Sunspots on May 29, 2024. Image credit: NASA SDO/HMI

Solar activity was at moderate levels in 24 hours to 12:30 UTC on May 29 due to M1 flares at 01:06 and 06:45 UTC from Region 3697 (beta-gamma-delta).

This region was previously numbered 3664. It produced around 100 M-class and over 10 X-class solar flares during its last rotation through the Earth side of the Sun in the first half of May. Multiple CMEs it produced at the time resulted in a G5 – Extreme geomagnetic storm — the strongest since 2003 — on May 10 and 11. On May 14, this region produced X8.7 solar flare — currently the strongest solar flare of Solar Cycle 25.

Over the past 24 hours, slight growth was observed in the group as it rotated further into view but it has shrunk considerably since its last rotation.

The location of this region currently does not favor Earth-directed CMEs but this will change in the days ahead as it rotates toward the center of the disk.

Region 3691 (beta-gamma-delta) also produced an M1 flare at 11:21 UTC today. This region exhibited slight growth and consolidation in its leading spots. The rest of the spot groups were relatively stable or in decay.

Solar activity will likely reach moderate levels with a few M-class flares while maintaining a chance for isolated X-class flares through May 31.

Isolated active levels, with a chance for G1 – Minor storming, are possible late on May 29 with any shock arrival from the May 27 CME. Quiet to unsettled conditions are expected on May 30 as any lingering shock effects wane. Mostly quiet conditions are anticipated to prevail on May 31.


05:28 UTC, May 30

The solar wind environment is expected to return to ambient-like levels over the course of May 30 and remain there through May 31. While the bulk of the material from the May 29 CME is expected to miss behind Earth’s orbit, influences from the CME’s flanking edge are likely to cause enhancements in the solar wind by late May 31 and continue into June 1, according to the SWPC.

Unsettled geomagnetic periods are expected during the early hours of May 30 due to lingering, weak transient effects from what is likely the shock from the May 27 limb event. G1 – Minor to G2 – Moderate geomagnetic storming is likely to commence by late May 31 and continue into June 1 due to flanking CME effects from the aforementioned X1.4 flare and subsequent CME eruption of May 29.


1 Forecast discussions – NOAA/SWPC – issued at 12:30 UTC on May 29 and 00:30 UTC on May 30, 2024


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