An impulsive solar flare measuring X1.3 erupted from an unnumbered active region on the SE limb of the Sun at 09:43 UTC on September 12.
Associated with this event were multiple discrete radio bursts and a 10cm Radio Burst (tenflare) lasting 2 minutes with a peak flux of 240 sfu.
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 Africa and parts of Europe and Asia at the time of the flare.
“Flares of this magnitude in and around solar maximum are generally not common, although not necessarily unusual,” SWPC forecasters said.
A coronal mass ejection (CME) was most likely produced by this event, but the region is still not in a location that favors Earth-directed CMEs. This will change in the week ahead.
Solar activity was at high levels over the past 36 hours, with several M-class solar flares, including M5.0, in addition to today’s X1.3.
WSA-ENLIL model shows 2 CMEs produced by AR 3814 over the past two days heading toward Earth, with impacts expected on September 13 and 14.
Solar wind parameters in 24 hours to 12:30 UTC today, indicated the arrival of two possible CMEs — the first produced on September 8 and the second on September 10.
There was a small increase in total field and wind speed at 14:24 UTC on September 11. The total field increased to a maximum of 12 nT by September 11 at 17:30 UTC, while solar wind speed increased modestly from around 350 km/s to near 380 km/s.
Then, at 02:54 UTC on September 12, a CME shock arrival was observed at the ACE spacecraft. The total field initially increased from 7 nT to 12 nT before a further increase to a maximum of 26 nT by September 12 at 09:35 UTC.
The Bz component deflected mostly southward for a prolonged period, reaching -20 nT. Solar wind speed initially increased to approximately 430 km/s with the shock arrival. A further increase to around 520 km/s was observed after 08:18 UTC on September 12.
G1 – Minor geomagnetic storm threshold was reached at 07:55 UTC followed by G2 – Moderate at 11:28 UTC.
G2 – Moderate geomagnetic are primarily affecting areas poleward of 55 degrees geomagnetic latitude.
Potential impacts include power grid fluctuations, particularly in high-latitude regions, where voltage alarms could be triggered.
Satellites in low Earth orbit may experience orientation irregularities and increased drag, while HF radio communications at higher latitudes could be disrupted due to signal fading.
Additionally, the aurora borealis may be visible as far south as New York, Wisconsin, and Washington state, offering a rare opportunity for those regions to witness this phenomenon.
Solar activity is expected to continue at moderate to high levels, with a 60% chance of M-class solar flares on September 12, 13, and 14. Additionally, there is a 15% chance of X-class flares occurring on each of these days.