The K7RA Solar Update

Solar activity was a bit lower this week. Seven new sunspot groups appeared. The only day with no new sunspot groups was Sunday, July 21. The next day two new sunspot groups arose, and all other days each had one new group.

Average daily sunspot number was 208.1, down from 215.9, while average daily solar flux declined from 226 to 193.

Geomagnetic numbers remained quiet, with average planetary A index unchanged at 6, and middle latitude numbers changing from 8 to 7.3. Future geomagnetic indicators look very quiet, for many weeks.  

The outlook for the next few weeks has solar flux reaching a short term maximum of 230 on August 12-14.

Spaceweather.com sent out this alert on July 25.

"MAJOR FARSIDE SOLAR FLARE: Europe's Solar Orbiter (SolO) spacecraft just detected the most intense solar flare of the current solar cycle. The X14-category explosion sprayed energetic particles throughout the solar system, causing high dose rates on Mars and even hitting Earth on the opposite side of the sun. The source of the flare could turn to face our planet late next week."

Predicted solar flux is 170 on July 26-27, 165 on July 28-29, 170 on July 30 through August 1, 165 on August 2, then 170, 180 and 190 on August 3-5, 200 on August 6-11, 230 on August 12-14, 210 on August 15, then 200 on August 16-18, 195 and 185 on August 19-20, 180 on August 21-23, 175 on August 24, 170 on August 25-27, 165 on August 28-29, and 170 on August 30-31. Flux values may climb to 230 again on September 8-9.

Predicted planetary A index is 10, 18 and 8 on July 26-28, 5 on July 29 through August 14, 8 on August 15-16, and 5 on August 17 through possibly mid September, a long stretch of very quiet conditions.

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere for July 25, 2024.

So here we are on Thursday, July 25th. Initially it appeared there would be a continued period of high solar activity, including flares. A logical continuing chain of predictions of increased geomagnetic activity, especially after major flares. Then finally at 1351 UTC a message came from NOAA containing the words: "WARNING: Geomagnetic Sudden Impulse expected. IP Shock Passage Observed: 2024 Jul 25 1315 UTC." The development continued and we could read the  message from Boulder, Co.: "SUMMARY: Geomagnetic Sudden Impulse Observed: 2024 Jul 25 1422 UTC. Deviation: 8 nT. Station: BOU."

After all, after a series of solar flares, this was no longer a major surprise while the week-old forecast by Tom Bayer (RWC Prague, Department of Geomagnetism, Budkov Observatory was fulfilled.

But it was not a big surprise, the previous major disturbance occurred on 28 June, or 26 days ago. If the mentioned geomagnetic disturbance develops and lasts longer, it will adversely affect shortwave conditions in the following days, possibly until Sunday. However, the recovery could be even faster due to the high solar activity.  F. K. Janda, A.R.S. OK1HH"

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

https://youtu.be/BgT8Y2cJjVw

Eruptions: https://bit.ly/4c2BNBb

Havoc: https://bit.ly/4dgMRf3

Reconstructed sunspot series:  

https://www.eurekalert.org/multimedia/1035992

Storm forecast:

https://bit.ly/46mWBSL https://bit.ly/4fjVPd5

Cycle 26: https://bit.ly/3ydtq7Y

Send your tips, reports, observations, questions and comments to k7ra@arrl.net.  When reporting observations, don't forget to tell us which mode you were operating.

For more information concerning shortwave radio propagation, see http://www.arrl.org/propagation and the ARRL Technical Information Service web page 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/

Also, check this: https://bit.ly/3Rc8Njt

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

Sunspot numbers for July 18 through 24 2024 were 276, 269, 212, 200, 173, 167, and 160, with a mean of 208.1. 10.7 cm flux was 208.7, 201.6, 207.4, 197.9, 185, 175.5, and 174.8, with a mean of 193. Estimated planetary A indices were 5, 5, 7, 5, 9, 5, and 6, with a mean of 6. Middle latitude A Index was 4, 5, 8, 9, 9, 8, and 8, with a mean of 7.3.