The K7RA Solar Update

The quiet sun continues, with still another week passing with zero sunspots. For 33 days in a row, no sunspot activity, as of Thursday, June 20. So far this year 62% of the days are without sunspots, really the same as all of last year, which was 61%.

Average daily solar flux over the past week was 67.1, down from 69 last week and 69.5 the week before.

Predicted solar flux over the next 45 days is 67 on June 21-28, 69 on June 29 through July 4, 68 on July 5-6, 69 on July 7-9, 68 on July 10-11, 67 and 66 on July 12-13, 67 on July 14-20, 68 on July 21-24, 69 on July 25-31, 68 on August 1-2, and 69 on August 3-4.

Predicted planetary A index is 5 on June 21-23, 10 and 8 on June 24-25, 5 on June 26 through July 5, 8 on July 6, 5 on July 7-9, 8 on July 10-11, 5 and 8 on July 12-13, 12 on July 14-17, 10, 8, 5, 8, 12 and 8 on July 18-23, and 5 on July 24 through August 1, then 8, 5 and 5 on August 2-4.

The summer solstice occurs at 11:54 AM EDT on Friday, June 21. And of course, the next day is ARRL Field Day. The low predicted planetary A index over Field Day weekend is a welcome sign, with little chance of any geomagnetic disturbance.

Geomagnetic activity forecast for the period June 21 to July 17, 2019 from F.K. Janda, OK1HH, who sees slightly more active geomagnetic conditions on Field Day weekend.

Geomagnetic field will be:
Quiet on June 27, 30, July 9
Quiet to unsettled on June 22, 28-29, July 3, 8, 10-11, 13-17
Quiet to active on June 21, 23, 26, July 1-2, 4-5, 12
Unsettled to active on June 24-25, July (6- ) 7
No disturbed days predicted.

Solar wind will intensify on June (23) 24-27, (28), July 5-7, (8-9,) 10-11

Parenthesis means lower probability of activity enhancement.

Martin McCormick, WB5AGZ, commented that he doesn’t think the solar flux has ever been below 66, where it was a few days ago, so we must be at solar minimum. But I pointed out that if you look at page 11 in this Preliminary Report and Forecast, it shows predicted flux values going even lower: ftp://ftp.swpc.noaa.gov/pub/warehouse/2019/WeeklyPDF/prf2283.pdf

But I don’t believe those numbers. I don’t see how it is possible that solar flux will go below 60 in 2021 and 2022. I keep checking at the beginning of every month, waiting for this prediction to be corrected, but so far haven’t seen it.

Rich Zwirko, K1HTV, and Steve, NN4X, reported a transatlantic 2 meter contact by D41CV: https://bit.ly/2RstTcP

An article about Europe’s L5 project, and what it means for space weather forecasting: https://bit.ly/2L4thc7

Dr. Skov’s most recent video: https://youtu.be/F5Wa6bXGy_I

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.

Instructions for starting or ending email distribution of ARRL bulletins are at http://arrl.org/bulletins.

Sunspot numbers for June 13 through 19, 2019 were 0, 0, 0, 0, 0, 0, and 0, with a mean of 0. 10.7 cm flux was 67.5, 68, 66.7, 65.9, 66.3, 67, and 68, with a mean of 67.1. Estimated planetary A indices were 10, 8, 4, 4, 3, 4, and 4, with a mean of 5.3. Middle latitude A index was 12, 13, 6, 6, 5, 3, and 4, with a mean of 7.

Source: ARRL