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Solar activity ranged from low to high.\u00a0 <\/span>Region 4087 produced the strongest event of the period, an impulsive R3 flare on May 14 at 0825 UTC near the NE limb.\u00a0 <\/span>The region also produced R2 flares at 0325 and 1119 UTC.\u00a0 <\/span>Finally, three R1 events were produced by the region on May 14 and 15.\u00a0 <\/span>Region 4086 also produced an R3 event, with a flare observed on May 13 at 1538 UTC. <\/span><\/p>\n No proton events were observed at geosynchronous orbit.\u00a0 <\/span>However, a weak enhancement, which peaked below the S1 threshold, was observed on May 13 following the R3 event from Region 4086. <\/span><\/p>\n Geomagnetic field activity was at quiet levels on May 12 and 13. Late on May 16, enhancements in solar wind parameters, associated with the onset of a positive polarity CH HSS and possible influence from the southern periphery of the CME that left the Sun on May 12, increased activity to active levels. <\/span><\/p>\n Forecast of Solar and Geomagnetic Activity May 19 – June 14 2025: <\/span><\/p>\n Solar activity is expected to be at low levels, with a chance for R1-R2 (minor-moderate) events, over the outlook period. <\/span><\/p>\n No proton events are expected at geosynchronous orbit. <\/span><\/p>\n The remainder of the outlook period is expected to be at normal to moderate levels. <\/span><\/p>\n Geomagnetic field activity is likely to be elevated above quiet levels for most of the next 27 days due to multiple, recurrent, coronal hole features.\u00a0 <\/span>G2 (moderate) conditions are likely on May 29 and June 13; G1 (minor) conditions likely on May 19, May 28, and June 14; active conditions are likely on May 30 – June 01, and June 10; unsettled levels are likely on May 20-23, May 27, June 02-07, and June 11-12.\u00a0 <\/span>Quiet conditions are expected for the few remaining days of the outlook period. <\/span><\/p>\n Weekly Commentary on the Sun, the Magnetosphere, and the Earth’s Ionosphere – May 22, 2025, from F. K. Janda, OK1HH. <\/span><\/p>\n Compared to previous months, there was a significant decrease in solar activity in May.\u00a0 <\/span>For example, on May 2, there were only two groups of spots on the entire solar disk observed.\u00a0 <\/span>After that, spot activity in the northern half of the solar disk increased slightly, but solar flux dropped significantly during the second third of the month.\u00a0 <\/span>Additionally, a large coronal hole appeared in the southern hemisphere of the sun.\u00a0 <\/span>Although this coronal hole was observed during previous rotations in March and April, it is much larger this time. <\/span><\/p>\n Consistent with this observation, after geomagnetic activity quieted down at the end of April, we experienced several days of strong geomagnetic disturbances in the first third of May.\u00a0 <\/span>Starting in the second third of May, the solar flux dropped significantly, reaching values not seen since October 2024. <\/span><\/p>\n The combination of low solar activity and high geomagnetic activity resulted in a significant deterioration of ionospheric shortwave propagation conditions, manifested by a drop in the critical frequencies of the F2 layer and an increase in attenuation and scattering.\u00a0 <\/span>This occurred especially on May 7-12 and May 14-18, and is likely to continue in the coming days. <\/span><\/p>\n The latest attempts to forecast further developments suggest that conditions should improve by the end of May.\u00a0 <\/span>The summer ionosphere of the northern hemisphere of Earth is characterized by lower maximal frequencies and higher lows, not counting the sporadic layer E surprises. <\/span><\/p>\n The Predicted Planetary A Index for May 24 to 30 is 6, 5, 5, 8, 25, 30, and 20, with a mean of 14.1.\u00a0 <\/span>The Predicted Planetary K Index is 2, 2, 2, 3, 5, 6, and 4, with a mean of 3.4.\u00a0 <\/span>10.7 centimeter flux is 120, 120, 120, 130, 135, 135, and 140, with a mean of 128.5. \u00a0<\/span><\/span><\/p>\n For more information concerning shortwave radio propagation, see and the ARRL Technical Information Service web page at, . For an explanation of numbers used in this bulletin, see \u00a0<\/span>. Information and tutorials on propagation can be found at, . <\/span><\/p>\n