Sunspots disappeared again this week, with a blank sun on April 28, and continuing every day since.

Average daily sunspot numbers dropped from 20 to 3.6, while average daily solar flux decreased from 73.4 to 69.3.

Average daily planetary A index declined from 11.9 to 4.4 and average mid-latitude A index went from 8.6 to 5.

Predicted solar flux is 67 on May 4-5, 68 on May 6, 69 on May 7-10, 68 on May 11-13, 70 on May 14-28, 68 on May 29 through June 9, and 70 on June 10-17.

Predicted planetary A index is 5 on May 4-5, then 18, 22, 16, 12 and 8 on May 6-10, 5 on May 11-16, then 42, 12 and 8 on May 17-19, 5 on May 20 through June 1, then 8, 15, 12, 10 and 8 on June 2-6, 5 on June 7-12, then 42, 12, and 8 on June 13-15 and 5 on June 16-17.

F.K. Janda, OK1HH of the Czech Propagation Interested Group has been compiling this weekly forecast since 1978. 

“Geomagnetic activity forecast for the period May 4-29, 2018

Geomagnetic field will be: 

Quiet on May 23-26, 28-29 

Mostly quiet on May 14, 16, 21-22, 27

Quiet to unsettled on May 4, 11-13, 19-20 

Quiet to active on May 5, 8-10, 15, (18) 

Active to disturbed on May (6-7,) 17 

Solar wind will intensify on May 5-7, (8-11,) 17-18, (19-20, 26-27) 

Remark: 

- Parenthesis means lower probability of activity enhancement. 

- With regard to ongoing changes, current forecasts are continuing to be less reliable.”

Thanks to British ham Max White, M0VNG, and others for alerting us to the recent buzz about the current solar cycle perhaps reaching a minimum sooner than predicted: https://bit.ly/2HN8fdn

Consensus seemed to place the approaching solar minimum around two years from now in 2020, but recent trends suggest the minimum may appear sooner. Does this mean the turnaround and following increase may also come sooner than previously anticipated?

K9LA has info on this: http://k9la.us/May18_Solar_Minimum_and_Spotless_Days.pdf

Also: http://k9la.us/html/monthly_feature.html

New from Dr. Skov: https://youtu.be/ylecUN5LgYA  “On the Ledge About Stealthy Solar Storms”

Dear Tad,

“Sometimes I wish I had started this Space Weather Woman thing a decade ago. That way I would be able to do a direct comparison with how things were during our last solar minimum in 2008. But then I realize, I wouldn't have had the benefit of you giving me timely reports from your local areas on social media. I wouldn't have heard you talking about the impacts you were experiencing during these solar events. This reminds me how grateful I am to all of you today. If it weren't for you, I would never know the extent to which Space Weather affects our everyday lives.

“This brings me to this week's forecast video. I am still shaking my head that we managed to miss a stealthy solar storm that brought aurora clear down to Illinois, USA. Guaranteed, national grids were on high alert as we crossed through the G2-level storm threshold. The irony that this stealthy solar storm occurred while we convened a workshop on how to predict them is not lost on me. In fact, it’s kind of a cosmic cattle prod. If we can experience such a strong solar storm that surprised us all-- so near solar minimum-- what does that say about our forecasting ability?

“I hope events like these serve as a wakeup call to us scientists, forecasters, and meteorologists alike. Although this week the Earth-facing side of the Sun is reasonably quiet, I will take this moment to reflect on all the work we have yet to do. In fact, that's exactly what I was doing while sitting on my window ledge during my last night in Switzerland (see the picture above). I was reflecting. Thanks so much for reminding me how important all of this is.

Cheers,

Tamitha"

Ever seen this? https://ham.stackexchange.com/

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 April 26 through May 2, 2018 were 14, 11, 0, 0, 0, 0, and 0, with a mean of 3.6. 10.7 cm flux was 69.4, 68.7, 70.2, 71.1, 70.2, 68.4, and 67.1, with a mean of 69.3. Estimated planetary A indices were 4, 6, 4, 4, 6, 3, and 4, with a mean of 4.4. Estimated mid-latitude A indices were 4, 5, 5, 3, 10, 3, and 5, with a mean of 5.