Solar indices barely changed over the past week, with average daily sunspot numbers rising from 25.3 to 33, and average daily solar flux dropping from 97 to 87.4.

Average daily planetary A index rose from 7.1 to 8.9, and average daily mid-latitude A index rose from 7 to 9.

Predicted solar flux for the near term is 80 on June 3-7, 85 on June 8-10, 80 on June 11-17, 85 on June 18-21, 80 on June 22-26, 75 on June 27 through July 4, and 80 on July 5-14.

Predicted planetary A index is 10, 35, 32, 15 and 8 on June 3-7, 5 on June 8-10, 12 on June 11-13, 8 on June 14-15, then 5, 15 and 10 on June 16-18, 5 on June 19-22, then 10, 12, 8, 20 and 12 on June 23-27, 5 on June 28-29, then 8, 15, 20 and 15 on June 30 through July 3, then 5 on July 4-7 and 12 on July 8-10 and 8 on July 11-12.


F.K. Janda, OK1HH sent us his geomagnetic activity forecast for the period June 3-29, 2016:

Geomagnetic field will be:
Quiet on June 9, 20, 22.
Mostly Quiet on June 8, 15-17, 21, 23, 29.
Quiet to Unsettled on June 7, 10, 13-14, 28.
Quiet to Active on Jun 3-4, 5-6, 11-12, 19, 24-25, 26-27.
Active to Disturbed on June 18.

Increases in solar wind from coronal holes are expected on June (6 -)7-8, (14 -)16-17, (26, 30)

Remarks:
- Parenthesis means lower probability of activity enhancement.
- Reliability of predictions is slightly reduced.


Some interesting tools for examining sunspot data:

http://harvard.voxcharta.org/tag/sunspot-databases/

Also, a paper about the same:

http://arxiv.org/pdf/1606.00669.pdf


Joe, K1YOW, of Harvard, Massachusetts wrote: “I was wondering. For the month of May, almost every day, there was a good 6 meter SpE (sporadic-E) opening in Europe, yet here in North America, openings were sparse. When looking at the DX maps every day, there seemed to be a SpE cloud somewhere over Europe – sometimes over France, then Greece, then Germany, then Eastern Russia, etc. Yet, whatever is causing the SpE clouds to appear over Europe does not seem to be happening here in North America.

“Is there any insight why SpE clouds would form over one area so frequently and with such good strength and not over other areas? If it was random, then I would expect to see SpE clouds now and then everywhere over the planet. Europe seems to be the hot spot of 6 meter activity these days for whatever reasons.”

I don’t know, but I will check. It seems that they are sporadic, but not random with any even distribution, but I don’t think that answer is very helpful.


Tracking our 3-month average of daily sunspot numbers, remember that the peak in the current cycle was centered on February and March of 2014, at 146.4 and 148.2.

For the past year that moving average was 77.7, 76.3, 69.1, 67.5, 64.5, 64.6, 58.5, 55.4, 53.5, 49, 45.3 and 43.1. So that last number sums all the sunspot numbers from March 1 to May 31, which is 3,964, and divides by the number of days, which is 92, yielding a smoothed sunspot number of approximately 43.08696.


A few days ago there was a big drop in the predicted solar flux numbers over the next month and a half. The daily forecast comes to us from ftp://ftp.swpc.noaa.gov/pub/forecasts/45DF/ . If you look at the solar flux forecasts issued on May 28 and compare the numbers to those issued on May 29, you will see the predicted average over the 7 days from May 31 to June 6 shift from 91.4 down to 75. Another area to inspect are the forecasts issued on May 29 and May 30 for the period from June 7 through June 14.


For more information concerning radio propagation, see the ARRL Technical Information Service at http://arrl.org/propagation-of-rf-signals. For an explanation of the 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 May 26 through June 1 were 30, 19, 31, 25, 56, 40, and 30, with a mean of 33. 10.7 cm flux was 91.7, 90.4, 87.7, 83, 86.2, 86.6, and 86, with a mean of 87.4. Estimated planetary A indices were 4, 10, 14, 7, 11, 10, and 6, with a mean of 8.9. Estimated mid-latitude A indices were 4, 12, 13, 8, 9, 10, and 7 with a mean of 9.