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Solar activity forecast for the period May 10 - May 16, 2024

Activity level: moderate to high ( very high )
X-ray background flux (1.0-8.0 A): in the range C2.0 - C9.2
Radio flux (10.7 cm): a fluctuation in the range 120-282
Events: class C (3-9/day), class M (0-9/period), class X (0-5/period), proton (0-1/period)
Relative sunspot number (Ri): in the range 80-260

Vlastislav Feik
RWC Prague, Astronomical Institute, Solar Dept., Ondrejov, Czech Republic

Geomagnetic activity forecast for the period May 10 - May 16, 2024

Quiet: May 13 - 14, 16
Unsettled: May 12 - 13, 15 - 16
Active: possible May 9 - 11
Minor storm: May 10 - 11
Major storm: possible May 11
Severe storm: 0

We expect minor to major storm during coming two days. This event is expected because of the last multiple CME emited since Wednesday, May 8, and Thursday, May 9.
Another active event is possible at the end of currently forecated period, about Wednesday, May 15. Nevertheless, the probability of significant storming event is lower than in the coming days.
Between these events, we expect at most quiet to unsettled conditions.

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 May 10 - May 16, 2024

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere – May 9, 2024

This week, the number of sunspot groups was smaller than in previous weeks (decreased from nine on Monday to six on Wednesday), but two of them (AR3663 and AR3664) are really big. Moreover, both have a beta-gamma-delta magnetic configuration, indicating the possibility of producing strong solar flares. Moderate flares (M-class) were observed several times a day and large flares (X-class) were not an exception.

Although AR3663 is now approaching the northwestern limb of the solar disk, the overall solar activity is certainly not decreasing, quite the contrary: AR3664 continued to grow rapidly, and has merged with neighbouring AR3668 to rival the large Carrington spot of 1859 in size. If it were to produce a CME eruption similar to 1859, and if the CME were to hit the Earth, the so-called "Carrington event" could be repeated, with potentially devastating consequences for power and communications grids.

So far, on the lower shortwave bands, we have seen rapid and large increases in attenuation during large flares, up to and including disruption of communications for tens of minutes to hours. The phenomenon is abbreviated SWF (Shortwave Fading), belongs to the SID (Sudden Ionospheric Disturbance) group. SWF is named after two physicists, John Howard Dellinger and Hans Mögel, as the Dellinger effect, or sometimes Mögel-Dellinger effect.

Solar flares with CMEs in the western half of the solar disk appear to be followed by an increase in geomagnetic activity and a marked fluctuation in shortwave propagation conditions around the weekend, with a slow return to average conditions in the following days.

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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