Weekly forecast

Solar activity forecast for the period April 04 - April 10, 2025

Activity level: low to moderate
X-ray background flux (1.0-8.0 A): in the range B9.5-C5.0
Radio flux (10.7 cm): a fluctuation in the range 90-185
Events: class C (2-15/day), class M (1-9/period), class X (0-1/period), proton (0-1/period)
Relative sunspot number (Ri): in the range 50-180

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

Geomagnetic activity forecast for the period April 04 - April 10, 2025

Quiet: Apr 7 - 8
Unsettled: Apr 5 - 6, 8 - 9
Active: Apr 4, 9 - 10
Minor storm: Apr 4, 9 - 10
Major storm:  unlikely about Apr 9
Severe storm: 0

Next days, we expect two active events with potential minor to major storming event.
The first one can be expected tonight or during next day (March 3 - 4); the other one can be expected at the end of currently forecasted period, i.e. April 9 - 10.
Between these events, we expect quiet to unsettled intermezzo, generally.

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 April 04 - April 10, 2025

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere – April 3, 2025

A harbinger of a somewhat more dramatic development in the Sun-Earth system was the helioseismological observation of a larger active region on the far side of the Sun. This region appeared on the northeastern limb of the solar disk as AR4046. It was followed by the larger, more magnetically complex, growing and eruptively active AR4048. Concurrent with the increase in solar activity, the geomagnetic field remained quiet from March 29 to April 1, a favorable combination for ionospheric evolution.

The intensified solar wind from the coronal hole margins in the western half of the solar disk was the cause of the geomagnetic disturbances, which caused a significant decrease in the critical frequencies of the ionospheric F2 layer from 2 April onwards, together with an increase in the attenuation of radio waves, to which the increased concentration of particles in the solar wind - both electrons and especially protons - contributed.

At the time of writing, the prediction of the onset of the recurrent disturbance on the night of 4/5 April is valid. The cause is the passage of the Earth through a region of enhanced solar wind in the corotating interaction region (CIR) structure.

In the next two weeks, the author of these lines will be in hospital. He will send his next post after his return.

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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