A Type IV radio emission was detected at 15:14 UTC. This type of emission occurs in association with major solar eruptions and is typically linked to strong coronal mass ejections and solar radiation storms.
Additionally, a 10cm Radio Burst (TenFlare) lasting 24 minutes and with a peak flux of 380 sfu was associated with this event.
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.
Images acquired by NASA Solar Dynamics Observatory (SDO) show a large CME was produced during the eruption. While the location of the region doesn’t favor Earth-directed CMEs, we’ll have to wait for updated coronagraph imagery for any meaningful analysis.
Solar activity was at low levels over the past 24 hours, with a couple of notable C-class flares. A faint CME was observed in LASCO C2 imagery at 04:23 UTC on March 27. The likely source was linked to a C3.9 solar flare from Region 4043 at 03:01 UTC the same day. Preliminary analysis and model output indicate this CME may deliver a glancing blow to Earth by March 31.
Later, at approximately 14:55 UTC on March 27, a 19-degree-long filament centered near S28E26 began to erupt. However, modeling of this second event suggests that the majority of the associated plasma is expected to pass south of Earth’s orbit.
Solar wind parameters in 24 hours to 12:30 UTC today reflected waning positive polarity coronal hole high speed stream (CH HSS) effects. The total field was primarily between 5 to 7 nT, and the Bz component was +/- 5 nT. Solar wind speeds gradually decreased from peaks near 840 km/s to near 620 km/s by the end of the period. Phi was predominantly positive, with brief excursions into a negative solar sector.
Quiet to unsettled geomagnetic field conditions, with isolated active periods, are expected to persist through March 29. Quiet to unsettled conditions are expected to prevail on March 30 as CH HSS effects come to an end.
References:
1 Forecast Discussion – SWPC – Issued at 12:30 UTC on March 28, 2025