Update 4 Dec. 06:00 CET
Fast solar wind from 3/4 December on, G1-G2 geomagnetic storm possible; large and complex sunspot groups, high flare and CME potential
Synopsis, review, outlook
1.12.2025 05:00 CET – The coronal hole CH04- becomes geoeffective from 3.12. with stream interaction region and subsequent fast solar wind. G1-G2 geomagnetic storm possible.
Region ex 4274 is now 4299, the new region in the centre 4297 and 4294 has been split: the leading spot is now 4298
The very large and complex region 4294 (ex 4281) produced numerous solar flares (C- and M-class) and CMEs (coronal mass ejections, solar storms), but not Earth-directed. It is currently relatively quiet. It is followed by region 4296, not quite as large and complex, but there could be more to come beyond the eastern edge.
4294 shows flux emergence and complexity especially in the rear and centre part – a decreasing tendency (decay) can be observed in the front area. This can change at any time.
Region ex4274 in the northeast continues to cause excitement – flares and CMEs also came from here – most recently an X1.9 flare with CME early on 1 December. It is currently completing its third rotation and was formed as the fast-growing region 4246 at the beginning of October ☞ Quiet sun, fast solar wind, soon to be more active and high solar activity and earth-directed CMEs. It has not yet received a new number from the Space Weather Prediction Centre – it’s about time.
Update 1.12. 13:30 CET: The region is now called 4299
Very atypical and unusual for this solar cycle: large, complex active regions at similar longitudes both north and south of the solar equator producing flares and CMEs. As time progresses, Earth-directed CMEs become increasingly likely, which could have the potential to produce bright auroras but also prominent space weather (radiation storms, radio blackouts, GPS disturbances, geomagnetically induced currents). It is currently not possible to make an exact forecast as to whether this will actually happen and, if so, when.
Region 4294 (left) shows numerous “moray eel eruptions” – filamentous material that shoots out like a tube only to immediately fall back along the same path, which is similar to the behaviour of moray eels in coral reefs.
A view of the corona of the eastern limb: It is very puffy and contains a lot of magnetic field.
The following graphic clearly shows the increase in solar activity in the form of solar flares: numerous M-class flares late on 28 November and on 29 November, a general increase in the background level, a slight decrease in between and only flares in the C-class range, most recently an X-1.9 flare from region ex4274.
☞ raumwetter.de/echtzeitsonnenwind
X1.9 Flare & CME on 1/12/2025 at 02:45 UTC (region 4299)
X1.9 Flare 02:57 UTC 12-01
Coronal mass ejection to the north-east
Just after publishing this post it happened: Region ex 4274 (now 4299) fired an X-flare and probably produced at least one CME to the northeast.
X1.9 Flare & complex eruption
Update 1.12. 14:30 CET – Coronal waves visualised by HaloCME (Nariaki Nitta https://x.com/halocme/status/1995400636494733546)
Radioburst
GPS was presumably disturbed by the flare in the Earth’s daytime range https://x.com/TamithaSkov/status/1995403417720909869:
GOES X-ray flux, GOES XRS derivative, SDO AIA 304 light curve
Radiogram 10 – 80 MHz shows broadband interference (sweeps, bursts) from the shortwave to the FM range
e-Callisto radiograms from the new solar radio telescope in Wairakei, New Zealand, operated by DLR https://astrodoncel.uah.es/dashboard/resultados.php?estacion=NZ-WAIRAKEI-DLR&fecha=2025-12-01
CMEs (“solar storms”) – Glancing blowa possible on 3.12./4.12.
2.12. 01:30 CET – About two to four CMEs were produced in connection with the flare. One of them with earth-directed components, which, however, have to fight their way through the high-speed stream of CH04- and are weakened in the process.
There is a possibility that the stream interaction region of CH04- will be strengthened by grazing CME components (magnetic field, dynamic pressure). SWPC and MOSWOC see good chances for G1-G2 (Kp5-6) geomagnetic storm on 3 Dec/ 4 Dec and slightly increased chances for short episodes with G3 STRONG STORM which would also mean chances for aurora in Central Europe. However, we had a similar situation 27 days ago (one rotation ago) with CMEs from the northeast and a high-speed stream in front of it. What arrived here was weak and barely recognisable as a CME.
The side view of the Sun-Earth axis (STEREO A HI1 instrument) shows CMEs that tend to move away from the Earth, which speaks against significant CME influences on 3/4 December.
☞ Met Office (MOSWOC) Enlil in the esa Space Weather Dashboard swe.ssa.esa.int/metoffice-enlil-e-federated
Sunspot group cluster in the southeast
The middle part of the cluster – region 4294 – is huge but of manageable complexity, with C-class flares and hardly any CMEs.
1.12. 0000z – 1900z
Since the late afternoon of 1 December, flux emergence has been observed north of the central sunspot. In addition, a rotation of the centre spot is clearly visible, which leads to a twisting of the surrounding magnetic field above it. So there is possibly a development towards more complexity and activity.
Synoptic map 2.12.
2.12. 20:00 CET – 4299 in the northeast is quiet, 4296/4294/4298 are quiet, CH04- blows fast solar wind to Earth on 3.12./4.12., SWPC issues G2 MODERATE STORM Watch for 3.12., 4.12.
Combined arrival of Stream Interaction Region, Sector Boundary Crossing and CME components – aurora likely
3.12. 18:30 CET – Persistently negative Bz values (north-south component of the interplanetary magnetic field) lead to high magnetic convection. At the moment, the probability of auroras on the northern horizon in Central Europe is high.
Northern lights 3.12./4.12.
3.12. 21:00 CET – Substorm around 20:50 CET – The aurora is faded from the almost full moon with 98% brightness.
Collm, Saxony, IAP camera, 51°N 12°E, 19:49 UTC, 19:54 UTC (20:49, 20:54 CET)
www.iap-kborn.de/index.php?id=2375
Rax, Alps near Vienna, 47°N, 15°E, 20:50 CET (1950 UTC)
raxalpe.panomax.com/ottohaus?t=2025-12-03+20-50-00&r=355&z=129&tl=46
Amtsberg, Erzgebirge, 50°N 13°E, 20:50 CET (1950 UTC)
amtsberg.panomax.com?t=2025-12-03+20-50-00&r=358&z=113&tl=0
Update 4.12. 01:00 CET – Positive Bz values are currently suppressing auroral activity in Central Europe
M6 flare from region 4300 – CME to the east
4.12. 06:00 CET – Suddenly and unexpectedly, a small filament exploded when it touched the field lines (loops) of the small sunspot region 4300 in the east (left) of the Sun at 0244 UTC, 4.12. Magnetic reconnection, a strong solar flare (M6.0) with broadband radio emissions and a plasma eruption (coronal mass ejection, CME) were the result. The resulting Type-II radio sweep has an estimated velocity of 345 km/s. The associated CME is very unlikely to reach Earth.
Detailed animation of the eruptive M6.0 flare
It is easy to see how the magnetic field lines of different polarity touch each other. The flare is caused by suddenly released electrons that hit the ‘surface’ (photosphere) at an accelerated rate
The dark areas indicate missing plasma/magnetic field that has been ejected from the corona
Meanwhile, the large cluster in the southeast remains quiet, showing little to no change and little complexity (a few smaller delta spots).
More updates always on X or bluesky
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