Subj : The ARRL Solar Report To : QST From : ARRL de WD1CKS Date : Fri Mar 07 2025 19:10:48 03/07/2025 Spaceweather.com[1] is reporting "A Hole In The Sun's Atmosphere" that should reach Earth on March 9 and 10. Solar activity has been at moderate levels for the past 24 hours. The largest solar event of the period was a M1 event observed on March 5 at 1150z from Region 4016. There are currently 10 numbered sunspot regions on the disk. Solar activity is expected to be low with a chance for M-class flares and a slight chance for an X-class flare on March 7 and 8. There is a chance for isolated minor solar radiation storm levels throughout the period if any of the returning/developing magnetically complex regions are active and produce an event. Geomagnetic field activity is expected to be at quiet to unsettled levels on March 7 to 9, 19 to 24, and on March 29.ÿ Active levels are expected on March 10 to 18, and then on March 25 to 28, with possible G1 (Minor geomagnetic storm) conditions on March 12 to 15 associated with recurrent negative polarity Coronal Hole influences. Quiet to unsettled conditions are expected on as weak, glancing CME effects continue to wane with quiet conditions prevailing on March 7.ÿ Unsettled to active levels are expected on March 8 as CIR - a CIR is a Corotating Interaction Region, its primary effect creates disturbances in the solar wind by interacting between fast and slow streams of solar plasma - effects ahead of a recurrent, negative polarity Coronal Hole become geoeffective. The NOAA Space Weather Prediction Center with its Geomagnetic Activity forecast for March 7 to 9 has a 40% chance of Active activity on March 8, a 40% chance of a Minor storm on March 9, a 15% chance of a Moderate storm on March 9, and a 1% chance of a Strong/Extreme storm during this same reporting period. Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere - March 6, 2025, by F. K. Janda, OK1HH: "The combination of relatively low total solar activity and a larger number of geomagnetic disturbances caused a worsening of shortwave propagation conditions in February. However, the outlook for March is better, not least because of the approaching equinox (which occurs on 20 March). "Solar activity will begin to increase more rapidly after the larger sunspot groups return to the Sun's disk (which is the half of the Sun's surface visible from Earth). At its eastern limb we should see their activity as early as mid-March. They will approach the centre of the disk just around the Vernal Equinox on March 20. "But even before that, the scenario may be somewhat different. In the north-west of the solar disk, we see a large coronal hole, which is likely to be the source of a strong solar wind that will probably affect the Earth's ionosphere sooner than we expect. But this too could be a harbinger of a further upsurge in solar activity. So - within reason - all good news." For more information concerning shortwave radio propagation, see http://www.arrl.org/propagation[2] and the ARRL Technical Information Service web page at, http://arrl.org/propagation-of-rf-signals[3]. For an explanation of numbers used in this bulletin, see http://arrl.org/the-sun-the-earth-the-ionosphere[4] . Information and tutorials on propagation can be found at, http://k9la.us/[5] . Also, check this: https://bit.ly/3Rc8Njt[6] "Understanding Solar Indices" from September 2002 QST. The forecast 10.7 centimeter flux for March 7 to 13 is 150, 150, 150, 155, 160, 170, and 180, with a mean of 59.3.ÿ The forecasted Planetary A Index for March 7 to 13 is 5, 5, 8, 15, 15, 25, and 30, with a mean of 14.7.ÿ The forecast Planetary K Index for March 7 to 13 is 2, 2, 3, 4, 4, 5, and 5, with a mean of 3.6. ÿ [1] http://Spaceweather.com [2] http://www.arrl.org/propagation [3] http://arrl.org/propagation-of-rf-signals [4] http://arrl.org/the-sun-the-earth-the-ionosphere [5] http://k9la.us/ [6] https://bit.ly/3Rc8Njt --- þ Synchronet þ Whiskey Lover's Amateur Radio BBS .