Register Account

Login Help


The K7RA Solar Update


We saw zero sunspots from April 21 through May 2, but on May 3 sunspots returned. Average daily sunspot number rose from zero last week to 16.1 this week, and average daily solar flux increased as well, from 67.5 to 73.5.

Both the average middle latitude and planetary A index this week were 6.6, and last week those numbers were 4.7 and 5.9 respectively.

Predicted solar flux is 75 on May 10-11, 73 on May 12-15, 74 and 76 on May 16-17, 72 on May 18-20, 68 on May 21-22, 67 on May 23-26, then 69, 68, 69, 70 and 72 on May 27-31, 75 on June 1, 76 on June 2-13, 72 on June 14-16, 68 on June 17-18, 67 on June 19-22 and 69 on June 23.

Predicted planetary A index is 5 on May 10, 14 and 12 on May 11-12, 5 on May 13-19, 8 on May 20, 5 on May 21-27, then 10, 12, 8 and 10 on May 28-31, then 5, 12 and 14 on June 1-3, 8 on June 4-6, 5 on June 7-15, 8 on June 16, and 5 on June 17-23.

Geomagnetic activity forecast for the period May 10 until June 5, 2019 from F.K. Janda OK1HH.

Geomagnetic field will be:

Quiet on May 10, 18-19, 22-23, 26-27

Quiet to unsettled on May 13-17, 21, 24-25, June 1-5

Quiet to active on May 11-12, 30

Unsettled to active on May 20, 28-29, 31

Active to disturbed-none

Solar wind will intensify on May (10,) 11-12, 14, (20,) 21-23, 29-31, June 1.

Parenthesis means lower probability of activity enhancement.


Jeff Hartley, N8II, in West Virginia wrote on May 4: “We are in a bit of a funk waiting for sporadic E to improve. Starting around 1900Z last Saturday and Sunday April 27-28, 20 meters began closing to north Florida in the Florida QSO Party and was completely closed by 2200Z. Then some sporadic E appeared and 20 was open to most of Florida from around 2345Z-0145Z. On 40 meters, there was no skip zone, so the callers from everywhere drowned out the Florida mobiles they were calling.

“Due to the higher MUF, the mobiles were also weaker than normal on 40 meters Saturday evening, but fixed stations were still pretty loud.

“Today, May 4, is the 7th call area QSO Party. Twenty meters did not open well until about 1415Z and signals were good until around 1700Z, after which they were much weaker and absolutely nothing was heard on 15 meters. They were the worst 7 area QSO Party conditions that I can remember.

“Most evenings around 2100-2300Z, 20 meters is wide open to southern Europe (many S9+ signals) despite the low SFI, but all DX signals are pretty weak by 1300Z almost every morning.”


The latest from Dr. Tamitha Skov, the Space Weather Woman, WX6SWW:

And another:


Steve Justus, W4SAJ, lives in Central Florida and was on 10 meters last Saturday (May 4) running FT8 mode at 100 W and beaming toward Australia with a 4-element mono-band Yagi. He was called by a station in Beijing, and is curious about the possible propagation mode, since Steve was not beaming in that direction. But FT8 is so efficient with decoding weak signals that this contact does not surprise me, although the signal strength may have surprised Steve.


Mike Schaeffer, KA3JAW, in Easton, Pennsylvania wrote Thursday, May 9: “This evening, while monitoring CB channel 29 (27.285 MHz) AM mode between 0020-0203 UTC, May 10)  while the MUF reached 74 MHz over Maidenhead grid square EM53 (Starkville, MS), with the solar flux being 76, the following state stations were heard: Alabama, Florida, Georgia, Illinois, Indiana, Kentucky, Minnesota, North Carolina, Ohio, Tennessee, and West Virginia. 0020 UTC is 14 minutes after local sunset, 8:06 pm EDT.

“According to NOAA solar wind prediction models, the Earth is going to get slammed with a solar storm on May 11 at 1000 UTC. Expect noisy propagation conditions on the high frequency bands.”


This just in, via WW1ME, VE7DXW and AF7TI: It shows you recent foF2 readings from Point Arguello in Southern California. foF2 is the highest frequency reflected vertically from the ionosphere using an ionosonde.

Here is a list of ionosondes:

You can check data from other locations by plugging the station code (such as BC840 for Boulder, Colorado) into the Point Arguello URL (replacing PA836), like this:

I only know definitions of a few of the parameters listed, such as foF2 and TEC (Total Electron Content). I hope to have more info on these tools next week.


If you would like to make a comment or have a tip for our readers, email the author at,


For more information concerning radio propagation, see the ARRL Technical Information Service at For an explanation of numbers used in this bulletin, see

An archive of past propagation bulletins is at More good information and tutorials on propagation are at

Monthly propagation charts between four USA regions and twelve overseas locations are at

Instructions for starting or ending email distribution of ARRL bulletins are at

Sunspot numbers for May 2 through 8, 2019 were 0, 11, 12, 14, 25, 27, and 24, with a mean of 16.1. 10.7 cm flux was 69.2, 69.8, 72.3, 73.5, 76, 78.7, and 75.3, with a mean of 73.5. Estimated planetary A indices were 12, 7, 10, 4, 5, 5, and 3, with a mean of 6.6. Middle latitude A index was 13, 8, 9, 4, 5, 5, and 2, with a mean of 6.6.





Instragram     Facebook     Twitter     YouTube     LinkedIn