The K7RA Solar Update

New sunspot group 2739 appeared on April 17, and the daily sunspot number rose to 24. The new sunspot has a polarity indicating it is still part of old cycle 24, the current sunspot cycle. This reporting week (April 11-17) the average daily sunspot number rose from 6.9 to 14, while average daily solar flux increased from 75.4 to 76.4.

Sunspots have been visible on every day since April 7, so as of April 18 that is 12 continuous days.

Geomagnetic indicators were quieter, with average planetary A index declining from 10.6 to 6.4.

Predicted solar flux for the next 45 days is 75 on April 19, 70 on April 20-21, 68 on April 22-25, 69, 70 and 69 on April 26-28, 71 on April 29-30, 70 on May 1, 72 on May 2-3, 77 on May 4, 79 on May 5-6, 78, 79 and 77 on May 7-9, 78 on May 10-17, 71 on May 18-19, 69 and 68 on May 20-21, 69 on May 22-23, 70 and 69 on May 24-25, 71 on May 26-27, 70 on May 28, 72 on May 29-30, then 77 on May 31 and 79 on June 1-2.

Predicted planetary A index is 5 on April 19-26, then 10, 8 and 5 on April 27-29, 10 on April 30 through May 2, then 7, 5 and 13 on May 3-5, then 10, 14 and 7 on May 6-8, 8 on May 9-10, 5 on May 11-20, then 10, 8 and 5 on May 21-23, 10, 8 and 5 on May 24-26, 10 on May 27-29, then 7, 5, 13 and 10 on May 30 through June 2.

Jon, N0JK reports that summer sporadic-e season began on April 14 when he copied K2PL (Virginia) and KE3QZ (Maryland) from Jon’s home in Kansas on six meters.

Geomagnetic activity forecast for the period April 19 until May 15, 2019 from F.K. Janda, OK1HH.

Geomagnetic field will be:

Quiet on April 19, May (12 - ) 13

Quiet to unsettled on April 20-22, 25, 27, May 3, 8, 10-11

Quiet to active on April 27, May 2, 4

Unsettled to active on April 23, 26, 28-30, May 1, 5-7, 9

Active to disturbed April 24

Solar wind will intensify on April 22-24, (25,) May 1-3, 9-13

Parenthesis means lower probability of activity enhancement.

Jeff, N8II, sent this report last Friday, April 12, too late for ARLP015: "There was not much action on 17 or 15 meters today. However, I did catch C5DL on 15 and 17-meter CW around 2000Z and worked them on both bands easily. The signal on 15 meters was peaking S4-5 at a beam heading of 130 degrees (true heading about 70). Then, after 2100Z, I managed to work AM70URE/9 in Ceuta, Africa on 15-meter SSB beaming to the south Atlantic on scatter. He was working South America, so his antenna was in the best position to work the scatter. Signals from south Europe were good at 2030Z on 20 meters; one Italian was S9 +20 dB and 2 others very loud. EA3GWK in Spain was S9+15db."

Here is what I believe is an older video from Tamitha Skov, WX6SWW, about the solar magnetic field when it reverses: http://www.spaceweatherwoman.com/can-the-suns-magnetic-field-flip/

You’ll find interesting images of sunspots here: https://earthsky.org/todays-image/photos-sunspot-ar-2738-apr-2019

If you would like to make a comment or have a tip for our readers, email the author at k7ra@arrl.net.

For more information concerning radio propagation, see 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/.

Monthly propagation charts between four USA regions and twelve overseas locations are at http://arrl.org/propagation.

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Sunspot numbers for April 11 through 17, 2019 were 13, 14, 14, 11, 11, 11, and 24, with a mean of 14. 10.7 cm flux was 78.5, 77.3, 77.9, 75.4, 75.4, 74.2, and 76.1, with a mean of 76.4. Estimated planetary A indices were 7, 9, 8, 4, 8, 6, and 3, with a mean of 6.4. Middle latitude A index was 6, 7, 7, 3, 8, 6, and 3, with a mean of 5.7.