Subj : The ARRL Solar Report To : QST From : ARRL de WD1CKS Date : Fri Jun 20 2025 17:54:46 06/20/2025 On Friday, June 20, Spaceweather.com[1] reports that, in addition to it being the first day of Summer in the Northern Hemisphere, on June 19 the Sun produced another X-class flare causing a shortwave radio blackout over the Pacific Ocean. Solar activity reached high levels when Region AR4114 produced the strongest event of the period, an X1.9 flare at 2350 UTC. The region remained the most complex on the disk despite being in a decay phase. The other numbered spotted regions on the visible disk were either mostly stable or in gradual decay. No Earth-directed CMEs were observed in available coronagraph imagery. R1 to R2 (Minor-Moderate) radio blackouts are likely with a chance for X-class flares (R3-Strong) through June 21, mostly driven by the potential from Regions AR4114, AR4115, and AR4117. Coronal Hole High Speed Stream conditions are expected to persist with waning influences into June 21.ÿ Unsettled conditions are expected to continue. Solar wind parameters continued to reflect a positive polarity CH HSS (Coronal Hole High Speed Stream) regime. The geomagnetic field is expected to be at quiet to unsettled levels on June 21, and at quiet levels on June 22.ÿ Geomagnetic field activity is likely to reach G1 (Minor) storm levels on June 25 and 26 due to negative polarity CH HSS influences. Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere, June 19, 2025, by F. K. Janda, OK1HH: "Solar activity is still at the peak of its eleven-year cycle, even though it reached its maximum last summer (with a monthly average of R = 216 in August last year and a smoothed average of R12 = 160.8 for October last year). The change from last year is the shift of sunspot activity from the southern to the northern half of the solar disc. The appearance of new sunspot activity in the southeast in recent days, close to the solar equator, came as a slight surprise. "This Spring, especially in May and early June, we could not fail to notice frequent periods of solar wind intensification and, consequently, a number of geomagnetic disturbances, which caused the critical frequencies of the ionospheric F layer to drop to values corresponding to significantly lower solar activity. In recent days, there has been only a slight improvement. "Most forecasts for future solar activity predict a continuing decline, but if we assume higher activity in the currently setting sunspot groups, we can expect an increase after their appearance on the north-eastern limb of the solar disc in July. Overall, calmer conditions can be expected during the coming Summer, although shortwave propagation conditions will continue to be slightly worse than would correspond to the level of solar activity." The latest solar report from Dr. Tamitha Skov, WX6SWW, can be found on YouTube at, https://www.youtube.com/watch?v=3RXJT7qLT0A[2] . For customizable propagation charts, visit the VOACAP Online for Ham Radio website at, https://www.voacap.com/hf/[3] . For more information concerning shortwave radio propagation, see http://www.arrl.org/propagation[4] and the ARRL Technical Information Service web page at, http://arrl.org/propagation-of-rf-signals[5]. For an explanation of numbers used in this bulletin, see http://arrl.org/the-sun-the-earth-the-ionosphere[6] . Information and tutorials on propagation can be found at, http://k9la.us/[7] . Also, check this: https://bit.ly/3Rc8Njt[8] "Understanding Solar Indices" from September 2002 QST. The Predicted Planetary A Index for June 21 to 27 is 5, 5, 8, 12, 25, 20, and 15, with a mean of 12.9.ÿ Predicted Planetary K Index is 2, 2,3, 4, 5, 5, and 4, with a mean of 3.6.ÿ 10.7 centimeter flux is 138, 135, 125, 125, 130, 125, and 125, with a mean of 129. ÿ [1] http://Spaceweather.com [2] https://www.youtube.com/watch?v=3RXJT7qLT0A [3] https://www.voacap.com/hf/ [4] http://www.arrl.org/propagation [5] http://arrl.org/propagation-of-rf-signals [6] http://arrl.org/the-sun-the-earth-the-ionosphere [7] http://k9la.us/ [8] https://bit.ly/3Rc8Njt --- þ Synchronet þ Whiskey Lover's Amateur Radio BBS .