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The K7RA Solar Update


Solar activity perked up over the July 2-8 period, with average daily sunspot numbers increasing from 35.9 to 109.1, compared to the previous seven days.

Likewise, average daily solar flux increased from 100.7 to 123.2.

Daily sunspot numbers were below 100 on June 16 through July 3, bottoming out at 25 on June 27.

A moderate geomagnetic storm on July 4-5 was caused by a solar wind stream. The mid-latitude A index from Fredericksburg, Virginia on July 4-6 was 21, 16 and 9. The planetary A index, based on observations from a number of Northern Hemisphere magnetometers was 19, 25 and 10 on those same days, and the college A index from Fairbanks, Alaska was 13, 31 and 18.

The current outlook (on Thursday before the bulletin is published) has predicted solar flux over the following seven days a bit weaker, averaging 118.1, Thursday through Wednesday.

You can check how the daily 45-day forecast of solar flux has done recently by going to and clicking “Download this file.”

The latest prediction from USAF/NOAA has solar flux at 125 on July 9-11, 122 on July 12, 120 on July 13, 115 on July 14-15, 125 on July 16, 130 on July 17-18, then 125, 115, 110 and 105 on July 19-22, then 100 on July 23-26, then 105, 110 and 112 on July 27-29, 115 on July 30-31, 120 on August 1 and 125 on August 2-4. Solar flux then peaks at 130 on August 10-14, then goes to 100 after August 18.

For planetary A index, the prediction 12, 25 and 18 July 10-12, 8 on July 13-14, 5 on July 15-17, 8 on July 18-19, 5 on July 20-25, 8 on July 26, 5 on July 27-30, then 18, 25 and 12 on July 31 through August 2, then 5 on August 3-5, then 20 and 25 on August 6-7, 8 on August 8-9, 5 on August 10-13, and 8 on August 14-15.

For the next few days USAF and NOAA predict the geomagnetic field at quiet to active levels July 10, then unsettled to minor storm levels on July 11, and unsettled to active levels July 12. They see a slight chance of M-class flare activity on July 10-12.

Australia’s Space Weather Services at the Bureau of Meteorology in Haymarket, New South Wales issued a geomagnetic disturbance warming at 2316 UTC on July 9. They said coronal hole effects starting late July 10 are likely to produce active periods and storm levels at higher latitudes on July 11. They repeat that increased geomagnetic activity is expected due to a coronal hole high speed wind stream over July 10-12. They see quiet to active conditions July 10, unsettled to minor storm July 11, and unsettled to active conditions on July 12.

By the way, all times expressed in this bulletin are in coordinated universal time, so 2355Z is the same as 2355 UTC and 2355 GMT. The date relates to the clock also, so 2355Z on July 10 is 6 minutes before 0001Z on July 11.

Petr Kolman, OK1MGW, has his own geomagnetic outlook, and he predicts the geomagnetic field will be quiet to unsettled July 10, active to disturbed July 11, quiet to active July 12, quiet to unsettled July 13-14, quiet on July 15, mostly quiet July 16-17, quiet to unsettled July 18, quiet to active July 19-21, quiet to unsettled July 22-25, mostly quiet July 26-29, quiet to active July 30-31, quiet to unsettled August 1-2, and mostly quiet August 3-5.

Petr expresses some uncertainty about the active to disturbed prediction for July 11, and suspects it may be like the following day, quiet to active. He also predicts an increase in solar wind on July 10-12 and 30-31.

Ed Stratton, W1ZZ, of Groton, Massachusetts in FN42ep, 30 miles NW of Boston, wrote: “I have been on 6 meters for a change of pace from HF DXing. In the past few days, from June 27 to July 5th I have logged many W4s, W9s, and W5s, and several VO1s.

“What is interesting is that there have been several openings to Europe, usually starting around 2000z to about 2300z. I have logged both SSB and CW QSOs with PJs, YVs, 9Y4, CTs, MW, MI, MD, G, EI, EAs, and an EA6.

“My working conditions are 150 watts and a 5 element Yagi only 22 feet up, and just recently it was 'armstrong' rotated. Now using a rebuilt 30 year old TR44.”

Check out photos of Ed’s antennas at

Ken Jones, K1DAT, lives in Millis, Massachusetts (FN42he) but operates from a summer cottage in Sagamore Beach (FN41rt) overlooking Cape Cod Bay.


Ken wrote, “I was at my summer cottage over the July 4 weekend and missed a new grid square. I was tuning around the CW end of six meters listening to an opening to Europe when I heard Ami, 4X4DK, calling CQ NA on 50.103. I only heard one other station calling him, like myself (5-7 times), but he didn’t hear us.

“So, I posted him on a DX cluster and within 20-30 seconds there were several stations calling him. I only heard one station work him, N3XX, and Ami had a hard time with the exchange.

“I e-mailed Ami and he reported back that he did not hear me, seeing my post he listened for me but had an S3-S5 noise level. Maybe that’s why more people couldn’t work him.”

Curious about the N3XX antenna system, I (K7RA) e-mailed him after seeing photos of his antennas on his page. Tim replied, “The three pictures on my page are all of the same array, just different views. The array is 4x7 LFA (Loop Fed Array) antennas, built for 6 meter EME, but works great for terrestrial also. There are two other taller towers here that support HF Yagis, wires, and a 5-element 6-meter Yagi.

“Six meter openings across the Atlantic have been pretty rare this season from this part of the country. Working 4X4DK was one of the few bright spots, even though I had a few QSOs with him in past years. I didn't hear him for very long, but he was 559 when we worked. He had trouble hearing me though, and gave me a 439 report.

“I haven't worked any new ones on 6 meters this season, but still hoping for good things over the next few weeks.”

You can read about Loop Fed Array Yagi antennas at,, and .

The IARU HF Championship is this weekend, and lasts for only 24 hours, 1200 UTC Saturday to 1200 UTC Sunday. See for details.

For more information concerning radio propagation, see the ARRL Technical Information Service at For an explanation of the numbers used in this bulletin, see An archive of past propagation bulletins is at More good information and tutorials on propagation are at

Archives of the NOAA/USAF daily 45 day forecast for solar flux and planetary A index are in downloadable spreadsheet format at and .

Click on “Download this file” to download the archive and ignore the security warning about file format. Pop-up blockers may suppress download. I’ve had better luck with Firefox than IE.

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 July 2 through 8 were 73, 91, 111, 131, 109, 118, and 131, with a mean of 109.1. 10.7 cm flux was 113.8, 112.3, 116.8, 124.8, 133.4, 132.6, and 128.9, with a mean of 123.2. Estimated planetary A indices were 3, 3, 19, 25, 10, 5, and 5, with a mean of 10. Estimated mid-latitude A indices were 4, 2, 21, 16, 9, 5, and 5, with a mean of 8.9.



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