A major solar flare measuring X1.5 erupted from Active Region (AR) 3936 at 04:14 UTC on December 30, 2024. The event started at 04:01 and ended at 04:28 UTC. The flare was associated with a 10cm Radio Burst (tenflare) from 04:08 to 04:15 UTC, with a peak flux of 1 000 sfu.
This event was followed by an impulsive X1.1 flare, which started at 04:29 and peaked at 04:31 UTC. This major event ended at 04:34 UTC and was produced by AR 3932. A tenflare lasting 2 minutes with a peak flux of 430 sfu was registered from 04:29 to 04:31 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 indicate significant radio noise associated 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 Indian Ocean, SE Asia, and Australia at the time of flare events.
X1.1 solar flare on December 29
The two X-class flares today follow a major X1.1 flare from AR 3936 at 07:18 UTC on December 29 and a flurry of M-class flares that began with an M1.0 at 02:35 UTC on December 29.
Eight M-class flares were produced before the X1.1 and another 13 before the end of the UTC day, making a total of 21 M-class and 1 X-class solar flares during the day.
Two coronal mass ejections (CMEs) were observed after yesterday’s X1.1 solar flare event.
The first was seen in NASA coronagraph imagery around 08:48 UTC and appeared to be a sympathetic event that originated in the vicinity of AR 3933.
The second was seen in NASA coronagraph imagery around 09:12 UTC as a northwesterly front possibly driven by the aforementioned X1.1 event.
Modeling of both of these CMEs suggests that they will miss south and ahead of Earth, respectively, according to the NOAA Space Weather Prediction Center (SWPC).
Other notable flares from AR 3936 included an M4.2 flare at 07:59 UTC and an M7.2 at 15:09 UTC. Region 3939 produced numerous M-class flares as well.
Earth-directed CME
A filament eruption that was associated with an M2.0 flare at 04:30 UTC on December 29 from AR 3939 resulted in an asymmetric, partial-halo CME first seen in NASA coronagraph imagery at approximately 06:24 UTC.
“Analysis and modeling of this CME indicated an Earth-directed event with arrival at Earth by mid-UTC day on December 31,” SWPC forecasters said.
Additionally, AR 3939 produced an M3.3 flare at 17:08 UTC that appeared to have resulted in yet another partial-halo CME, although a more faint, first seen in NASA coronagraph imagery around 18:00 UTC. Analysis and modeling of this event is ongoing.
Geomagnetic storm forecast
As a result of increased activity and Earth-directed CMEs, a G3 – Strong Geomagnetic Storm Watch is in effect for December 31.
SWPC said confidence is moderate to high in geomagnetic storming outcome, but exact storm strength and timing are lower due to the nature of the filament eruption.
This disturbance is expected to continue throughout December 31 before beginning to subside by January 1.
Keep in mind that the geomagnetic storm forecast at this time still doesn’t account for double X-class flares produced early December 30 and their possible impacts.
During G3 – Strong geomagnetic storms, voltage corrections may be necessary to maintain stability in power systems, and some protection devices may trigger false alarms. For spacecraft operations, the storm can cause surface charging on satellite components, increased drag on low-Earth-orbit satellites, and potential orientation issues requiring corrective measures.
Other systems can also experience disruptions, such as intermittent satellite navigation and low-frequency radio navigation problems, as well as irregularities in high-frequency (HF) radio communication.
Additionally, auroras associated with G3 storms have been observed at latitudes as low as Illinois and Oregon (around 50° geomagnetic latitude).
G3 storms occur approximately 200 times per solar cycle (11 years), or about 130 days per cycle.
Solar activity forecast
3929 – Beta
3932 – Beta-Gamma
3933 – Beta-Gamma
3935 – Alpha
3936 – Beta-Gamma-Delta
3937 – Alpha
3938 – Beta-Gamma
3939 – Beta
3941 – Beta-Gamma
3942 – Alpha
Solar Synoptic Map for December 30, 2024. Image credit: SWPC
There are currently 11 active sunspot regions on the Earth side of the Sun. Four of them have ‘Beta-Gamma’ magnetic configuration and one has ‘Beta-Gamma-Delta’ — all are capable of producing strong to major eruptions on the Sun.
Solar activity is expected to continue at moderate to high levels over the next three days, with a 75 – 80% chance for M-class solar flares and 25 – 30% for X-class as the conglomeration of regions approaches the Sun’s western limb.
References:
1 Forecast Discussion – NOAA/SWPC – Issued at 00:30 UTC on December 30, 2024
2 Major X1.1 solar flare erupts from Region 3936, CME impact possible on December 31 – The Watchers – December 29, 2024