Solar storm (CME) with Earth-directed components following an M1.8 flare and filament eruption

Update 2026-06-09, 2200 UTC

Eruption of a filament in the south-east↙︎ accompanied by a gradual, long-duration solar flare (class M1.8), radio emissions, and a CME with a partial halo and a complex core on 6 June at around 13:45 UTC. Its shock wave is almost certain to reach us; the core of the CME could graze or flank us – the ‘bulk’ is moving towards the south-east. Models predict arrival during the course of 8 June; a geomagnetic storm of intensity G2 MODERATE to G3 STRONG is possible, possibly even G4 SEVERE – under favourable conditions, mid-latitude auroras may also occur.

CME = Coronal Mass Ejection = solar eruption = solar storm

Overview (Synopsis)

2026-06-07, 0500 UTC – There are eight sunspot groups on the visible solar disc, of which 4458 has produced minor CMEs. 4456 and 4462 are growing (flux emergence) and are more likely to produce flares and CMEs. Region 4455, which recently sent three CMEs more or less in the direction of Earth, is decaying. Region 4463 was previously 4436 and had produced large CMEs and strong flares. It now consists of just a single sunspot. Perhaps it will revive again, or perhaps this is the end of it. New is 4464 – an anemone-shaped active region in the midst of a coronal hole.

A large filament snaked its way through Region 4461, having attempted to erupt several times – finally doing so successfully on 6 June at 1345 UTC. An energetic eruption accompanied by a CME, a Type II radio burst and the release of energetic particles was observed.

The CH62+ coronal hole on the western limb is still sending us fast solar wind. This is likely to decrease gradually. The connection with CH64+ is likely to be weak. The fast solar wind from CH63– is expected to reach us after the CME arrives (uncertain).

A comparison with the map of the last rotation shows a significant increase in the number of active regions and, at the same time, a dramatic decrease in the size of coronal holes – a clear indication that we are in the midst of a cyclical surge in activity (‘Rossby surge’), which occurs with a period of 6–12 months. Activity will slowly decrease again until there are very few or no sunspots left, and then it will rise again. As the sunspot minimum approaches, the surges become increasingly weaker.

2026-06-06, 13:45 UTC – Eruption

A filament is a tube of relatively cool, very dense plasma that is generated and held together by surrounding magnetic fields. If these fields change, the filament becomes unstable; sometimes it lifts off and erupts, and often it simply disperses into the corona.

Flare

We can see the entire corona wobbling around the flare – an explosive event

CME

Partial halo (= shock) towards the south-east + plasma clutter forming the CME core. The shock has a speed of around 1400–1700 km/s, the core (‘leading edge’) of 1000–1500 km/s – a fast CME.

Parts of the CME cross both the ecliptic plane and the Sun’s central meridian – it can therefore be assumed that the core contains components directed towards Earth.

Radio emissions

Type III, Type II and microwave radio burts were measured. Typical of a CME with a shock wave.

Energetic particles

A characteristic feature of gradual, long-duration flares is the release of energetic particles. Particles of up to 50 MeV have been detected; therefore, there are no dangerous high-energy protons, and the warning threshold for an S1-class radiation storm has not yet been exceeded.

The poor magnetic coupling with the region in the south-east is preventing a rapid, steep rise – however, as the shock front approaches and arrives, a further rise may occur.

The presence of energetic protons increases the conductivity of the ionosphere and may therefore intensify the potential geomagnetic storm.

Model predictions

SWPC (USA) and BoM (Australia) have agreed on a G3 watch for 8 June and a G2 watch for 9 June; MOSWOC (UK) issues a G3 watch for 8 June (0200 UTC – 2350 UTC) – MOSWOC does not issue G2 watches, so there is no warning for 9 June.

Most models predict arrival sometime on 8 June, with varying intensities and plasma velocities (600–1000 km/s). We are likely to see a strong shock, followed by a turbulent sheath phase. It remains to be seen whether the core of the CME will reach us or whether we will remain only within its outer envelope. The core does not appear to be well-structured, and it is not certain whether it contains a well-defined flux-rope structure at all.

If the CME does indeed arrive early, around 0600 UTC, the timing would be rather unfavourable for Europe and the aurora. If the CME arrives late and has a magnetic field with a sufficiently southern orientation, mid-latitude auroras in Europe are possible. The probability of a stronger event is higher than for the previous CMEs – in my opinion.

Updates

… take place here.

2026-06-08, 1400 UTC – The CME is on its way

The CME is still some distance from Earth (0.2–0.3 AU). An arrival late on 8 June or even as late as early on 9 June seems plausible. Whether it will then be a rather weak glancing blow or still a powerful flank hit is impossible to say. There are model runs that have calculated a strong but late impact (HUXt, alternative Enlil run from SWPC, some members of the MOSWOC ensemble).

Should the impact prove weak, the probability of auroras is nevertheless increased: the ring current is still active from the previous CME glancing blows and the high-speed stream from the coronal hole CH62+ (possibly also CH64+): the DST index is still around -50 nT – the magnetosphere is charged and active

2026-06-09, 0200 UTC – No sign of the CME so far

The latest image from the Heliospheric Imager is over 10 hours old. There is no new information here. No increase in suprathermal protons at L1 (EPAM) can be observed, so there is no sign of an approaching shock front. The measured neutron density in Oulu has not yet decreased significantly. The CME is therefore not in the immediate vicinity of Earth. There is still a possibility of a late arrival, but the possibility that the CME has missed us is also slowly coming into focus. In this case, a detailed investigation into the cause would be useful, as this would raise a number of questions.

2026-06-09, 22:00 UTC – Arrival, Analysis, Speculation

At around 09:55 UTC on 9 June 2026, parts of the CME reached us, significantly later than most models had predicted. We saw nothing of the fast shock, and what did reach us was no longer travelling very fast, with only slightly elevated magnetic field values – technically speaking, the CME did not miss us, but it certainly felt that way.

A more detailed analysis of SOHO LASCO C3, STEREO A COR 2 Science, GOES CCOR-1 Running Difference, STEREO Heliospheric Imager 1 Science Running Difference and Stars Removed shows that the fast shock did not propagate towards Earth, but towards the south-east. Its shape did not allow its expansion to reach us (probably). It is also possible that something hindered the shock or that it dissipated.

As operational model calculations do not take the inclination of CMEs into account, they assume a spherical object – however, the inclination often results in a complex propagation, and results for spherical propagation are then sometimes far away from reality. It is fairly certain that the CME continued to expand rapidly, but not in our direction.

It is not possible to say with certainty what exactly happened on an ad hoc basis. Perhaps this complex ejection also disintegrated on its own. To determine this, the eruption would need to be examined in detail once again, using data of scientific quality and possibly recreated using more computationally intensive models. This is a topic for a scientific paper. Unfortunately, not many people engage in such re-analyses, particularly when CMEs have missed us contrary to predictions, even though this is precisely what would yield the greatest insights.