Here’s the latest propagation forecast from Tad Cook (K7RA).
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Content provided by Tad Cook (K7RA), HQ ARRL, and W1AW.
Accessed on 13 March 2021, 0110 UTC, Post 1924.
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SB PROP @ ARL $ARLP011 ARLP011 Propagation de K7RA ZCZC AP11 QST de W1AW Propagation Forecast Bulletin 11 ARLP011 From Tad Cook, K7RA Seattle, WA March 12, 2021 To all radio amateurs SB PROP ARL ARLP011 ARLP011 Propagation de K7RA Although solar activity remains low, lately as a sunspot rotates to the west off the visible solar disc a new one emerges in the east. Sunspot group 2807 recently moved over the Sun's western horizon, but on March 9 new sunspot group 2808 moved across the eastern horizon, and a newer group (2809) has now emerged just south of the center of the solar disc. This brought the daily sunspot number higher from 11 on Wednesday to 23 on Thursday, March 11. Recent sunspot activity and solar flux still seem soft when compared to activity toward the end of 2020. In Propagation Forecast Bulletins ARLP048, 049, and 050 in 2020, (covering November 19 through December 9), average sunspot numbers were 27.9, 57.6 and 28.9 and average daily solar flux was 90.1, 108.1 and 91.9. For the past three weeks overall average daily sunspot numbers were 19 (the two weeks prior to that had no sunspots) and average daily solar flux was 77.1. We can't do anything except to wait and watch, but we can look forward to the Vernal Equinox next week on Saturday, March 20. Like the Autumnal Equinox in the Fall, this is always a positive influence on HF propagation when the northern and southern hemispheres are bathed in approximately equal amounts of solar radiation. You can count on it. Average daily sunspot numbers this week hardly changed, from 18.9 last week to 18.4. Average daily solar flux shifted marginally higher from 76.7 to 78.9. Solar wind has slackened, so average daily planetary A index went from 14.7 to 7.6, and the middle latitude numbers changed from 10.4 to 6.1. Predicted solar flux for the next 30 days is 78 on March 12-19, then 75, 76, 78 and 81 on March 20-23, 80 on March 24-25, then 78 and 76 on March 26-27, then 75 on March 28 through April 1, then 78 on April 2-3, and 70, 74, 76, 72, 71, 72 and 70 on April 4-10. After April 18, solar flux may rise again above 80, then back to 75 by April 24. Predicted planetary A index is 12, 20 and 10 on March 12-14, 5 on March 15-17, 12 on March 18-19, then 20, 18, 12 and 8 on March 20-23, 5 on March 24-27, then 25, 20, 20 and 10 on March 28-31, then 5, 15 and 8 on April 1-3, 5 on April 4-7, then 18, 12, 5 and 15 on April 8-11. A recurring coronal hole may rotate into a geo-effective position on April 15-16 and another around April 24-25, raising the planetary A index again to around 20-25. Geomagnetic activity forecast for the period March 12 to April 6, 2021 from F.K Janda, OK1HH. "Geomagnetic field will be: quiet on: March 17, (26-27,) April 1, 6 quiet to unsettled on: March 12-13, 16, 25, April 3-5 quiet to active on: March 21-24, 31 unsettled to active: March 14-15, 18, 29 April 2 active to disturbed: March 19-20, 28, 30 "Solar wind will intensify on: March (12-14, 18-19,) 20-23, (27,) 28-31, April (1-2). "Parenthesis means lower probability of activity enhancement. Predictability of changes remains very low, as there are ambiguous indications." Dennis, K7BV, reported: "March 7, while checking the bands for DX, I went to 15m FT8 about 1650z. The strongest signal by a huge margin was S79KW (LI75rj Seychelles) at +27 dB! After a quick contact, I moved to a clear frequency to CQ. Almost immediately 4S6RSP at -8 dB strong called. A few minutes later VU2AMW at -1 dB called. I also noticed YC5YZ calling CQ. Nothing else heard from the region but S79KW remained strong well after this brief 15 meters opening to Southern and Southeast Asia." Unfortunately the averages at the end of this bulletin sometimes change from the preview in Thursday's ARRL Letter. This is my fault and happens from time to time. Thanks so much to Don Wright, AA2F, who catches these every time, and makes sure the correct averages appear in Friday's bulletin. Aurora season in Colorado: https://bit.ly/3esaFkV David Moore sent this from Science News: "The aurora's very high altitude booster." https://bit.ly/3rGk2RS If you would like to make a comment or have a tip for our readers, please email the author at, firstname.lastname@example.org . For more information concerning radio propagation, see http://www.arrl.org/propagation and the ARRL Technical Information Service web page at, http://arrl.org/propagation-of-rf-signals. For an explanation of numbers used in this bulletin, see http://arrl.org/the-sun-the-earth-the-ionosphere. An archive of past propagation bulletins is at http://arrl.org/w1aw-bulletins-archive-propagation. More good information and tutorials on propagation are at http://k9la.us/. Instructions for starting or ending email distribution of ARRL bulletins are at http://arrl.org/bulletins . Sunspot numbers for March 4 through 10, 2021 were 32, 14, 23, 14, 12, 23, and 11, with a mean of 18.4. 10.7 cm flux was 81.4, 73.2, 77, 77.5, 79.9, 83.7, and 79.4, with a mean of 78.9. Estimated planetary A indices were 11, 5, 16, 10, 6, 3, and 2, with a mean of 7.6. Middle latitude A index was 11, 5, 11, 7, 5, 2, and 2, with a mean of 6.1. NNNN /EX