A 10 cm Radio Burst (TenFlare) lasting 6 minutes and with peak flux of 570 sfu was registered from 01:03 to 01:09 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.
SDO imagery shows a large coronal mass ejection (CME) lifting from the region and heading away from Earth. While the location of this region does not favor Earth-directed CMEs, the position it is in now favors solar radiation storms.
Radio frequencies were forecast to be most degraded over the Pacific Ocean at the time of the flare.
Solar activity intensified to high levels in 24 hours to 00:30 UTC today, with five M-class flares registered, according to NOAA’s Space Weather Prediction Center (SWPC). The largest of them was an M4.9 flare at 17:08 on April 23 from Region 4419 (beta-gamma-delta).
The region underwent significant evolution, including flux emergence in the leading spots, flux consolidation in the intermediary regions, and the development of a delta configuration in the leader alongside a mixed-polarity gamma configuration.
Region 4420 (beta-gamma-delta) also exhibited growth and consolidation, particularly within the trailing and intermediate spots, with increased shearing noted in intermediate areas. The remaining regions on the disk were in decay.
Notable eruptive activity was observed throughout the 24-hour period, with CMEs associated with each of the M-class flares.
A CME was observed to the NW following an M1.6 flare from Region 4419 at 04:35 UTC on April 23 and was first visible in LASCO C2 imagery at 05:00 UTC, while a CME to the NE was associated with an M1.2 flare from Region 4420 at 05:08 UTC on April 23 and first visible at 05:12 UTC.
These events were accompanied by Type II (1 033 km/s) and Type IV radio emissions. Modeling indicates the NW CME will pass ahead of Earth, while the NE CME is expected to result in a glancing impact on April 26.
Subsequent flaring from Region 4419 that are associated with observed eruptions include an M4.3 flare from Region 4419 at 08:53 UTC on April 23 which produced a NW CME (first seen at 09:12 UTC) associated with Type II emissions (722 km/s) and 10cm radio bursts, an M1.7 flare from Region 4419 at 14:00 UTC on April 23 which launched a NE CME (first seen at 14:24 UTC), and an M4.9 event at 17:08 UTC which produced an additional NE CME (first seen in GOES-19 CCOR1 at 18:15 UTC).
While analysis of the eruption associated with the M4.9 flare is ongoing, none of these are anticipated to impact Earth.
Finally, a diffuse eruption was observed in STEREO COR2 imagery at 12:23 UTC and LASCO C2 at 12:24 UTC. The source remains uncertain, with possibilities including a SE filament eruption or NE coronal dimming. Analysis of this event, as well as the potential for interaction between the multiple preceding CMEs, is ongoing.
Solar activity is expected to be at moderate levels through April 26, with a chance for X-class flares primarily driven by the ongoing complexity of Regions 4419 and 4420.
The likelihood for M-class flares is anticipated to increase today as a large sunspot region, currently identified in Solar Orbiter imagery beyond the east limb, rotates onto the visible disk.
The greater than 2 MeV electron flux is expected to be at moderate to high levels through April 26, primarily influenced by a weak positive polarity coronal hole high-speed stream (+CH HSS).
Transient flux suppressions are possible on April 26 from the anticipated glancing influence of the CME associated with the M1.2 flare from Region 4420.
The greater than 10 MeV proton flux is expected to remain at background levels, though there is a slight chance (10%) for levels to exceed S1 – Minor solar radiation storm thresholds due to the flare potential of Region 4419 as it rotates toward the western limb.
Solar wind parameters are expected to experience mild enhancements beginning April 24 due to the onset of a +CH HSS. Further enhancements are anticipated on April 26 associated with the arrival of the glancing influence from the CME originating from the M1.2 flare from Region 4420.
The geomagnetic field is expected to be mostly quiet to unsettled on April 24 and 25, with isolated active periods possible as the +CH HSS influences persist. Isolated G1 – Minor geomagnetic storming conditions are possible on April 26 in response to the arrival of the glancing CME impact.
References:
1 Forecast Discussion – NOAA/SWPC – Issued at 00:30 UTC on April 24, 2026