Weekly forecast

Solar activity forecast for the period December 20 - December 26, 2024

Activity level: low to moderate
X-ray background flux (1.0-8.0 A): in the range C1.0 - C3.0
Radio flux (10.7 cm): a fluctuation in the range 110-170
Events: class C (3-13/day), class M (3-10/period), class X (0-1/period), proton (0-1/period)
Relative sunspot number (Ri): in the range 70-180

Michael Vavra
RWC Prague, Astronomical Institute, Solar Dept., Ondrejov, Czech Republic

Geomagnetic activity forecast for the period December 20 - December 26, 2024

Quiet: Dec 20, 25
Unsettled: Dec 20 - 22, 23, 25
Active: Dec 21 - 24, 26
Minor storm: possible Dec 21 - 22, 24
Major storm:  0
Severe storm: 0

We expect geomagnetic activity enhance within coming days and also during the nearest weekend. In that time, we expect an active event due to the last coronal mass eject from December 17.
Other active event but less probably, is possible about the end of currently forecasted period.
Between two events, we expect, generally the activity at quiet to unsettled level.

Tomas Bayer
RWC Prague
Institute of Geophysics of the ASCR, Prague
Department of Geomagnetism
Budkov observatory (BDV)

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere December 20 - December 26, 2024

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere – December 19, 2024

Although the sunspot clusters are not as large as they were this autumn (the area of the largest ones is about half as large), they continue to produce moderate-sized flares (M-class, or at least C-class in the X-ray field) almost daily. However, the Earth is being affected by coronal mass ejections (CMEs), whose passes, while usually unable to produce a major geomagnetic storm, always affect the ionosphere.

The Sun will be at its lowest point in the northern hemisphere on 21 December 2024 at 09:19:54 UT. Astronomical autumn will end and astronomical winter will begin. In the lower layers of the Northern Hemisphere ionosphere, the attenuation is at its lowest of the year and so conditions are ideal for the propagation of signals from distant stations in the longer part of the shortwave. We have witnessed this repeatedly, especially during the last week, i.e. since mid-December.

Although the ionosphere of the northern hemisphere of the Earth is now the least ionized by solar radiation, it is on the far side of the Sun and clearly high activity, judging by the few CMEs that have hit the Earth from there. The Earth's ionosphere and magnetosphere felt the strongest hit on 17 December (at 0519 UT).

An increase in solar activity is expected in the next week, after active sunspot regions appear on the solar disk.

F. K. Janda, A.R.S. OK1HH
http://ok1hh.nagano.cz/
Emails: ok1hh(at)crk.cz, ok1hh(at)rsys.cz
Pmail: OK1HH(at)OK0NAG.#BOH.CZE.EU

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