The K7RA Solar Update

No sunspots have appeared since June 26. If we use predicted solar flux as a proxy, flux is expected to be less than 70 until July 8, this Sunday, so I would not expect sunspot activity to resume perhaps until July 13-23 when solar flux is expected to rise above 70.

Predicted solar flux is 68 on July 6-7, 70 on July 8-12, 72 on July 13, 75 on July 14-15, 77 on July 16, 80 on July 17-19, 77 on July 20-21, 73 and 71 on July 22-23, 70 on July 24-25, 69 on July 26-27, 68 on July 28 through August 5, 69 on August 6, 72 on August 7-9, 75 on August 10-11, 77 on August 12, 80 on August 13-15, 77 on August 16-17, then 73 and 71 on August 18-19.

Predicted planetary A index is 10 on July 6, 5 on July 7-14, then 15 on July 15, 5 on July 16-19, then 15, 8, 10, 18 and 7 on July 20-24, 5 on July 25-28, 8 on July 29, 5 on July 30 through August 10, 15 on August 11, 5 on August 12-15, then 15, 8, 10 and 18 on August 16-19.

Chip Margelli, K7JA, had a comment on the coverage of Field Day conditions last week: “I saw your propagation report re Field Day. I’m still trying to figure out which planet that represented.

“Conditions on Field Day were generally awful. The K index rising to 4 Saturday morning really tore up the bands and blew out the E layer here in the western US. Neither 6 nor 10 meters opened at all on Saturday, and there were only a few pop-up paths that emerged on Sunday on meters. On six, while much of the eastern part of the country had a big band, but in southern California we worked five whole stations in South Dakota. That was it.

“Twenty meters was fair at best, but it closed early Saturday night. Fifteen was a huge bust, and 40 was very disturbed, with heavy fading and East Coast signals generally huddling right at the edge of being audible. Forty meters never really took off to the east, causing our station to be at least 30% down from our anticipated numbers.

“It wasn’t a good weekend for propagation at all. It was especially disappointing because 6 meters had been wide open all week before Field Day, and a week after the event it was open across the country again.”

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 June 28 to July 4, 2018 were 0, 0, 0, 0, 0, 0, and 0, with a mean of 0. 10.7 cm flux was 69.5, 68.6, 68.8, 68.1, 66.6, 68.2, and 67.9, with a mean of 68.2. Estimated planetary A indices were 5, 4, 4, 3, 3, 4, and 5, with a mean of 4. Estimated mid-latitude A indices were 5, 3, 3, 4, 4, 5, and 4, with a mean of 4.

Source:ARRL