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The K7RA Solar Update

04/27/2018

Solar activity increased over the past week, with average daily sunspot numbers up from 5.4 to 20 and average daily solar flux rallying from 69.9 to 73.4. The previous week saw four days with no sunspots, and the recent week had sunspots on every day. New sunspot groups emerged on April 19 and 21.

Predicted solar flux is 69 on April 27-29, 68 on April 30 through May 3, 70 on May 4-16, 75 on May 17-29, 70 on May 30 through June 10.

Predicted planetary A index is 12 on April 27, 5 on April 28 through May 5, then 10, 15, 12, 10 and 8 on May 6-10, 5 on May 11-16, then 42, 12 and 8 on May 17-19, 5 on May 20-22, then 8 and 12 on May 23-24, 5 on May 25 through June 1, then 10, 15, 12, 10 and 8 on June 2-6, then 5 on June 7-10.

 

Geomagnetic activity forecast for the period April 27 to May 22, 2018 from F.K. Janda, OK1HH of the Czech Propagation Interest Group.

“Geomagnetic field will be:

Quiet on April 30

Mostly quiet on April 28, May 3, 14, 16, 21-22

Quiet to unsettled on April 27, 29, May 1, 4, 8, 11-13, 19-20

Quiet to active on May 2, 5, 9-10, 15, (18)

Active to disturbed on May 6-7, 17

Solar wind will intensify on April (27-29), May (2,) 5-7, (8-11,) 17-18, (19-20).

Remarks: 

- Parenthesis means lower probability of activity enhancement. 

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

 

Interesting videos with general information on sunspots and solar flares: http://www.thesuntoday.org/the-sun/solar-activity/

 

From the same source, multiple detailed images per day of the sun viewed at different wavelengths: http://www.thesuntoday.org/the-sun-now/

 

Dr. Skov will probably release a new space weather video after this bulletin is sent to ARRL HQ for distribution. This is a good place to check for her latest report: https://www.youtube.com/user/SpWxfx

 

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 19 through 25, 2018 were 14, 14, 34, 20, 22, 19, and 17, with a mean of 20. 10.7 cm flux was 70.8, 73, 76.8, 75.7, 73.9, 72.9, and 70.8, with a mean of 73.4. Estimated planetary A indices were 3, 47, 12, 5, 6, 5, and 5, with a mean of 11.9. Estimated mid-latitude A indices were 2, 29, 10, 5, 6, 4, and 4, with a mean of 8.6.

 

 



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