\n<\/p>\n
Solar activity has been low with only C-class solar flare activity.<\/p>\n
\nRegion 4465 underwent some decay and only produced a low-level\nC-class flare. Region 4469 decayed further and was inactive. Region\n4470 underwent some growth, but did not increase in magnetic\ncomplexity and was primarily inactive. The largest solar flare of the\nperiod, a C2.5 on June 17, came from just beyond the west limb with\nthe likely source being recently rotated out-of-view Region 4464. \n\nA coronal mass ejection (CME) became visible in STEREO coronagraph\nimagery on June 17 and Compact Coronagraph (CCOR) imagery\napproximately 30 minutes later. This eruption was first determined to\nbe far-sided due to SUVI 304 and 193 imagery; however, the\nbackfilling of a SOHO LASCO data gap prompted a re-analysis and it\nhas since concluded that there may be an Earth-directed component.\nModeling is currently ongoing.\n \nThere was an additional, faster, eruption off the east limb close to\nthe equator, with the resulting CME first appearing in LASCO C2\nimagery on June 17. Due to its faintness, this CME is not visible in\nother coronagraphs. Modeling of this event is also ongoing, but a\nsignificant Earth-directed component is not anticipated.\n \nSolar activity is likely to continue at low levels through June 20,\nwith a slight chance for M-class (R1-minor) solar flares due\nprimarily to the combined flare probabilities of Regions 4465 and\n4470.\n \nSolar wind parameters were indicative of a weak disturbance in the\ninterplanetary magnetic field (IMF), which was probably related to\nanticipated early-stage coronal hole high speed stream (CH HSS)\ninfluences. The phi angle was quite variable between sectors. Solar\nwind speed increased from 400 km\/s to nearly 500 km\/s before\ndeclining to about 450 km\/s. Mild solar wind disturbances and\nenhancements are anticipated through June 20 due to weak positive\npolarity CH HSS effects. \n\nWeekly Commentary on the Sun, the Magnetosphere, and the Earth's\nIonosphere June 19 by F. K. Janda OK1HH:\n\nThe low solar activity observed during the second decade of June will\nbe replaced by significantly higher activity in the third decade, as\nthe active regions observed by the Solar Orbiter on the far side of\nthe Sun will gradually emerge.\n\nGeomagnetic activity will generally be relatively low, and shortwave\npropagation conditions will be relatively favorable\u00e2\u20ac\u201dwithin the limits\nof the summer ionosphere in the Earth\u00e2\u20ac\u2122s northern hemisphere, that is.\n\nAnd, as was the case in the second third of June, we can expect a\nsignificant influence from the sporadic E layer.\n\nThe Predicted Planetary A Index for June 20 to June 26 is 10, 5, 8,\n12, 5, 5, and 5 with a mean of 7.1. The Predicted Planetary K Index\nis 3, 2, 3, 4, 2, 2, and 2 with a mean of 2.6. 10.7 centimeter flux\nis 132, 130, 112, 135, 136, 138, and 140 with a mean of 131.9.\n\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>