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The K7RA Solar Update


Australia’s Space Weather Services released this bulletin at 0700 UTC on August 24:




There is a chance of a glancing blow from a slow moving coronal mass ejection (CME) that may arrive over the next 24 hours resulting in periods of Active to Minor Storm conditions.



FROM 24-25 AUGUST 2018


24 Aug:  Quiet with the chance of Active to Minor Storm periods

25 Aug:  Unsettled


And now, the ARRL Propagation Bulletin:

Average daily sunspot number over the past reporting week was 13, up from 3.4 during the prior week. But average daily solar flux was down slightly, declining from 68.7 to 67.5. Average daily planetary A index rose from 6.9 to 10.1, and average mid-latitude A index changed from 7.3 to 10.4.

Sunspots have been visible every day for ten days in a row as of August 23, since first appearing on August 14, following a lull since June 27, with only three days showing any sunspots at all after that, July 21, and then August 1-2.

For a view of recent quarterly sunspot numbers and solar flux, check:

Predicted solar flux is 70 on August 24-30, 68 on August 31, 66 on September 1-5, 67 on September 6-10, 68 on September 11-15, 67 on September 16-19, 66 on September 20 through October 1, and 67 on October 2-7.

Predicted planetary A index is 8, 12, 8, 8 on August 24-27, 5 on August 28 through September 2, 12 and 8 on September 3-4, 5 on September 5-6, 15 on September 11-12, 12 on September 13-14, then 12, 18, 15, 12 and 10 on September 15-19, 8 on September 20-21, 5 on September 22-29, 15 and 10 on September 30 through October 1, 5 on October 2-3, 8 on October 4, and 5 on October 5-7.

The above numbers are updated daily, usually after 2205 UTC at:


Geomagnetic activity forecast for the period August 24 until September 19, 2018 from F.K. Janda, OK1HH.

Geomagnetic field will be:

Quiet on August 24, 31, September 1-2, 8-10

Quiet to unsettled on August 25, 30, September 5-6, 17-19

Quiet to active on August 26-27, September 4, 8, 16

Unsettled to active on August 28-29, September 3, 7, 11-15,

Active to disturbed -

Solar wind will intensify on August (28), September (10-11,) and 14-17.


- Parenthesis means lower probability of activity enhancement.

- Reliability of predictions remains low.

F. K. Janda, OK1HH


Bil Paul, KD6JUI, who often operates portable from a kayak in Northern California freshwater channels near Sacramento, wrote on August 19: "I heard about the recent burst of solar activity while vacationing at Lake Almanor in northern California. I noticed the solar flux took a temporary bump upward to 79 and I hoped for improved propagation. However, the only result I saw was increased levels of static noise (which temporarily reached S7 on my transceiver). The max usable frequency for me as a QRP operator was still 40 meters (CW).”

Bil published an article in the November 2016 issue of QST about operating on HF from fresh waters and the antenna he built for his boat. I have not confirmed with him when he operated from the lake, and I cannot find a burst in solar activity until I look back at June 20-22. That must be it. The solar flux numbers at the Penticton, BC observatory (measured three times per day, although the local noon measurement at 2000 UTC is official solar flux number for the day) over those three days was 80.5, 82.1, 82.4, 82.1, 81.5, 81.6, 81.1, 80.3, and 79.9.

We must look back at 2017 to find any numbers like that. I replied to Bil, "We won't often see improvement in MUF after a brief rise in solar activity. It helps, but needs to be sustained. Maybe in 2021, if we're lucky."


Steve Sacco, NN4X, of St. Cloud, Florida wrote on August 17, and noted contacts and stations he heard using WSJT-X on six meters at 50.313 MHz Steve was excited about hearing 9K2GS (Abdullah Bin Hamad, in Kuwait) from 1307-1311 UTC, but could not work him. He wrote, “Multiple decodes, but no QSO. Still super cool, especially for this late in the summer Es season."

He also logged K4MIL, W4TAA, VE2DLC, KB8ZR, N3DGE, N4OYT, VE9HF, K0PT, WA2TP, and N2SAB.


Jon Jones, N0JK wrote early on August 24, 2018: “A remarkable Es season, long lasting. Maybe the noctilucent clouds played a role?  Or upper atmosphere circulation.”


Dr. Tamitha Skov wrote on August 23: “I have a new "forecast shorty" ready for viewing on You Tube, but I wish it came without a warning label. A solar storm set to hit Earth on Saturday nearly mirrors Hurricane Lane, which is coming dangerously close to the Hawaiian Islands now and will hit by this weekend. At the time of this writing, the storm is a Category 4. The last time the islands got hit with a Category 4 storm was Hurricane Iniki in 1992. I've been getting messages from people, who remember living through Iniki, asking me if Amateur Radio will be impacted by this coming solar storm. They told me HF radio was a lifeline during Iniki and they wanted the comfort of knowing they would be able to rely on it again. All I could do was wince.

“The Hawaii Emergency Management Authority declared yesterday that Amateur Radio will be the emergency communications of choice between the islands during Hurricane Lane's passage. As such, I will be sure to keep you updated on the impacts of the solar storm when it arrives. I might even do a live public broadcast if it looks like it could help emergency responders know what kinds of disruptions they might be facing and/or communications windows they might have. Again, a huge thank you to the Patreon members, who are making these 'forecast shorties' possible. Frequent forecast updates such as these prove so critical at times like now-- you are helping families and communities stay safe!”

Here is her latest video:


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 August 16 through 22, 2018 were 12, 11, 11, 15, 15, 15, and 12, with a mean of 13. 10.7 cm flux was 68.3, 67.3, 67.2, 66.8, 68, 67.8, and 66.9, with a mean of 67.5. Estimated planetary A indices were 11, 13, 12, 8, 14, 7, and 6, with a mean of 10.1. Estimated mid-latitude A indices were 11, 14, 11, 8, 15, 6, and 8, with a mean of 10.4.