K7RA's Solar Report

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Last update: Friday, 14-May-2021 07:46:22 GMT

ARLP020 Propagation DE K7RA
Propagation Bulletin 20 ARLP020 From Tad Cook, K7RA
Seattle, Washington May 14, 2021
To all radio amateurs

Sunspot activity returned last Friday, and has held steady since. Average daily sunspot numbers rose from 11.9 to 21.1, and average daily solar flux was up 2.1 points to 74.3 for the reporting week ending May 12.

Geomagnetic activity was quiet until Wednesday when the planetary A index went to 41, as the result of a CME that blasted out of the sun on May 9. It was not expected to be very strong, but when it struck on May 12 it sparked a G3 class geomagnetic storm, the strongest in the current solar cycle.

The planetary A index rose to 41, far above an average of 3.8 on the previous six days. The average daily planetary A index for the week (May 6-12) was 9.1 and average middle-latitude A index was 7.4.

Predicted solar flux over the next month is 75 on May 14-19, 70 on May 20-21, then 72, 80, and 79 on May 22-24, then 78, 77 and 73 on May 25-27, 72 on May 28-30, 70 on May 31 and June 1, 71 and 75 on June 2-3, 76 on June 4-5, 74 on June 6-7, 75 on June 8-9, 77 on June 10, and 79 on June 11-13.

Note in the 45-day forecast that solar flux of 84 predicted for June 15 seems to be an outlier:


Odd that predicted solar flux would shift from 78 to 84 to 77. But we saw a similar prediction recently for that same value a week into the future, but any trace of it here seems to have disappeared down the memory hole:


There seems to be some problem accessing FTP (File Transfer Protocol) lately on some web browsers. It gradually disappeared from Microsoft Edge, then Firefox, then Chrome. I discovered that although I keep the Windows OS updated, the old Internet Explorer still exists on my PC, and it does not block FTP.

Predicted planetary A index is 5 on May 14-16, then 15, 12, 8, 5 and 8 on May 17-21, 5 on May 22 through June 5, then 8, 5 and 8 on June 6-8, then 8, 5, 12, 18, and 15 and on June 9-13.

Geomagnetic activity forecast for the period May 14 to June 8, 2021 from F.K. Janda, OK1HH of the Czech Propagation Interested Group, compiling this geomagnetic activity weekly forecasts since January 1978.

Geomagnetic field will be quiet on: May 19, 25-26, (27-31) quiet to unsettled on: May 21, 24, 31, June 1-8 quiet to active on: May (14-16, 18, 20-23) unsettled to active: May (17) active to disturbed: none

Solar wind will intensify on: May (16,) 17-18, (21-25,) 28-30

Remarks: - Parenthesis means lower probability of activity enhancement. - Contradictory indications significantly reduce the accuracy of the forecast.'D

Jon Jones, N0JK EM28 Kansas wrote "6m Es to W6 May 14 to Silicon Valley. Worked AH0U and N5KO both CM97. They are in the sporadic E "doughnut" between single & double hop Es.'D

Ken Brown, N4SO checks this graph of the EISN each day and "compares it with propagation on 30 and 17 meters. Of interest are stations in China, Japan, Korea, and Asiatic Russia propagated at 6000 miles plus.'D


The estimated international sunspot number (EISN) is a daily value obtained by a simple average over available sunspot counts from 85 worldwide observers in the SILSO network.

Also see:


Ken also reported:

W1AW Schedule on CW, 18.0975 MHz, 7 PM Code Bulletin, May 11, W1AW signals are 40 db over S9, so I called CQ QRP. Power set to all the way down on the Elecraft K2. Low setting reads .1 and W1 power meter reads the lowest power at 100 mW. 0049 UTC QRPp 18.076 MHz 100 mW

W3UA N4SO/QRP 18076.1 CW CQ 16 dB 22 wpm 0048z 11 May KM3T N4SO/QRP 18076.0 CW CQ 4 dB 22 wpm 0047z 11 May

and at 0126 UTC K7QO 18.077 MHz 3 watts QRP

May 11 FT8 mode 10.136 MHz

Long string of Japanese worked starting with a CQ from JA6VZ at 0745 UTC.

Stations worked/confirmed at 0931 UTC with JE1VTZ and extends to 1114 UTC with JA2KVD, and JM1FHL with over 26 worked.

Strongest stations were JE0ART at -3 db and JA1IOA at +5 db. Both of these are very strong and rare for a roughly 7000 mile path.

Several times (1011 UTC and 1028 UTC) the Band Activity was listing a complete string of Japanese call signs busy with a contact or calling CQ. My activity screen will list about 24 call signs.

Reverse Beacon Network

At the same time period I checked RBN 10 meters and found this for the very early time of 1043 UTC.

KC0VKN K4SE 28038.2 CW CQ 1 dB 7 wpm 1043z 11 May Locations are Tennessee (K4SE) and Oxford, Iowa. (KC0VKN)"

Thanks to the the ARRL Contest Update for the following.

Check this link for a reference on sporadic-e propagation:


See http://www.arrl.org/the-arrl-contest-update

Then check this for an interesting sporadic-e real time online tool:


Two recent reports from the Space Weather Woman, Dr. Tamitha Skov, WX6SWW:



For more information concerning shortwave radio propagation, see http://www.arrl.org/propagation and the ARRL Technical Information Service 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 May 6 through 12, 2021 were 0, 15, 17, 18, 36, 31 and 31, with a mean of 21.1. 10.7 cm flux was 70.8, 74.5, 71.6, 75.9, 76.5, 76.1, and 74.7, with a mean of 74.3. Estimated planetary A indices were 4, 3, 3, 4, 6, 3, and 41, with a mean of 9.1. Middle latitude A index was 2, 3, 4, 6, 8, 4, and 25, with a mean of 7.4. NNNN

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