\n<\/p>\n
Solar activity has remained at low levels this past week. The largest event of the period was a C3.4 flare originating from Region 4446.\u00a0<\/p>\n
Solar activity has remained at low levels this past week. The largest
\nevent of the period was a C3.4 flare originating from Region 4446.\u00a0
\n\u00a0
\nThere are nine numbered regions on the visible disk. Region 4452
\nshowed notable growth and new flux emergence. Region 4450 decayed to
\nplage, though unassociated transitory pores were observed to its east
\nand west. Region 4443 decayed into a unipolar spot as it approached
\nthe west limb following the loss of its leading components. Regions
\n4453, 4454 and 4455 were numbered during the period. Far-side
\nsatellite imagery from Solar Orbiter indicates that Region 4455 is
\nlikely a large bipolar group with its trailing opposite-polarity
\nspots still located behind the east limb and was numbered proactively
\ndue to its flaring potential. All other regions either continued in
\nslow decay or remained stable.
\n\u00a0
\nA faint, potentially partial-halo, coronal mass ejection (CME) first
\nseen in LASCO C2 imagery on May 26 and subsequently in GOES\/CCOR1 was
\nanalyzed. No obvious on-disk source exists. Modeling suggests a
\npossible glancing blow at Earth on May 31. Additionally, narrow
\neruptions associated with flaring from newly numbered Region 4444
\nwere seen in SUVI imagery but these features are well northward of
\nthe ecliptic plane with no Earth-directed components. No other
\nEarth-directed coronal mass ejections (CMEs) were observed in
\navailable coronagraph imagery.
\n\u00a0
\nSolar activity is expected to be at low to moderate levels through
\nMay 30. There remains a chance for isolated M-class flares
\n(R1-R2\/minor-moderate) driven by the eruptive potential of the
\nsoutheast sunspot groups and newly numbered Region 4454.
\n\u00a0
\nSolar wind parameters remained slightly elevated and possibly
\nindicative of weak negative polarity coronal hole high-speed stream
\n(-CH HSS)influences.\u00a0
\n\u00a0
\nSolar wind speeds varied modestly between 350 and 425 km\/s. The phi
\nangle was predominantly in the negative sector (towards the Sun),
\nthough minor deviations were observed later in the period.
\n\u00a0
\nSolar wind parameters are expected to remain mildly enhanced due to
\nweak coronal high speed stream (-CH HSS) influences through May 29. A
\nreturn toward near-background, nominal conditions is anticipated by
\nMay 30.
\n\u00a0
\nWeekly Commentary on the Sun, the Magnetosphere, and the Earth’s
\nIonosphere, May 28, 2026
\n\u00a0
\nObservations of the far side of the Sun by the Solar Orbiter probe
\nshowed us how a new and relatively large active region was
\napproaching the northeastern limb of the solar disk. But it wasn\u2019t
\nuntil it began to emerge on May 28 (designated as AR 4455) that it
\nbecame clear the recent rise in solar activity would continue.
\nFurthermore, the only significant coronal hole in the higher northern
\nheliographic latitudes is sufficiently far from other active regions,
\nso we need not expect a significant intensification of the solar
\nwind.
\n\u00a0
\nTherefore, we could expect calmer conditions in the Earth\u2019s
\nmagnetosphere and, at the same time, higher usable frequencies in the
\nionosphere for long-distance communications before their seasonal
\ndecline. However, summer in the ionosphere of the Earth\u2019s northern
\nhemisphere, with higher attenuation in the lower ionosphere during
\nthe long days, will often be enlivened by sporadic E layers in the
\nmid-latitudes until August.
\n\u00a0
\nFor more information concerning shortwave radio propagation, see<\/span>
<\/span>and the ARRL Technical Information<\/span>
Service web page at, <\/span><\/span>http:\/\/arrl.org\/propagation-of-rf-signals. For<\/span>
an explanation of numbers used in this bulletin, see<\/span>
<\/span>. Information and<\/span>
tutorials on propagation can be found at, <\/span><\/span> <\/span>.<\/span><\/p>\n