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The K7RA Solar Update


Over the seven days of our recent reporting week (February 18-24) average daily sunspot numbers declined from 56.7 (over the previous seven days) to 37.9.

Average daily solar flux was down from 107.8 to 93.9. But geomagnetic indicators were also down (generally a good thing) with average planetary A index decreasing from 17.7 to 10.1 and average mid-latitude A index declining from 12.6 to 7.3.

The latest prediction from USAF has solar flux at 95 on February 26-27, 90 on February 28, 85 on February 29, then 95, 100, 105 and 110 on March 1-4, 115 on March 5-7, 110 on March 8-9. 105 on March 10-13, 100 on March 14-15, 95 on March 16-19, then 100 and 105 on March 20-21, and 110 on March 22-23. Solar flux then peaks at 115 on March 29 through April 3.

Predicted planetary A index is 5 on February 26-28, 8 on February 29, 12 on March 1, 10 on March 2, 8 on March 3-4, then 5, 15, 10 and 8 on March 5-8, 5 on March 9-10, then 8, 5 and 12 on March 11-13, 30 on March 14-16, 15 and 8 on March 17-18, then 5 on March 19-21 and 8 on March 22-26. The rest of the 45-day prediction shows planetary A index at 30 on April 10, but that is a long way off. You can get daily updates of both solar flux and planetary A index predictions at usually after 2120 UTC.

OK1HH predicts quiet geomagnetic conditions on February 26, quiet to unsettled February 27, quiet to active February 28-29, mostly quiet March 1-2, quiet to active March 3-5, active to disturbed March 6, quiet to active March 7, quiet to unsettled March 8-9, quiet to active March 10, quiet on March 11-12, mostly quiet March 13, quiet to active March 14, active to disturbed March 15-16, quiet to active March 17, quiet March 18, mostly quiet March 19, quiet March 20, mostly quiet March 21, quiet to unsettled March 22 and mostly quiet March 23.

OK1HH also sees increases in solar wind on February 29 through March 3 and March 14-17, although he sees a lower probability of this on February 29 and March 1.

Jon Jones, N0JK, of Lawrence, Kansas wrote, in a message titled “What a difference a year makes on ten meters, In the 2015 ARRL DX CW contest I worked numerous JA's, UA0, KH8, 3D2, Africa, and even a few Europeans on 10 meters while fixed mobile (from his parked car) with a small CB mag. mount whip from Kansas. The solar flux was 116.

“This year was a different story. Using a much better fixed mobile antenna -- a full size 1/4 wave vertical on the roof top -- no Europeans or JAs. Best DX was V6A and NH2DX -- both were loud -- Sunday afternoon. Solar flux 96. A fellow local K3PA reported good conditions on 80 meters Sunday morning with a nice run of JA's.”

N0JK in last week’s bulletin referred to a DX map which illustrated a February 18 six meter sporadic-e opening. You can download that map via

Jim Smith, K3RTU, in Pennsylvania wrote, “Weather in Southeast Pennsylvania has not been the best for a while so I have not been out with my Backpack QRP as much as I would have liked. However, Monday, February 22 was a nice day so I headed out to my favorite state park.

“I was using my KX3 transceiver with an MFJ 17 ft stainless steel whip mounted about 4 ft off the ground with several counterpoise wires. I found 17 and 15 meters to be in fairly good shape. Lots of South African stations on both bands, but the pile ups were fierce. However, I was able to work ZD7FT on St Helena Island running 10 watts SSB on 15 meters.

“The most amazing thing to me about this contact was that ZD7FT's antenna was an OCFD (off-center fed dipole) and not some monster Yagi with lots of gain. From where I was operating to ZD7FT is just under 6,000 miles. On 17 meters I was able to work VE4DL also using 10 watts SSB.

“By the way, I received a QSL from 3DA0NJ in Swaziland that same day in the mail. I had worked him back in October from the same state park running 10 watts SSB from my IC-703 transceiver and a Buddistick vertical on 17 meters. From the park to Swaziland is 8200 miles.”

This weekend is the CQ World-Wide 160 Meter SSB Contest. It begins today, February 26 at 2200 UTC and runs until Sunday, February 28 at 2200 UTC. See for details. Conditions should be good with low geomagnetic activity, at least for the start of the contest.

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

My own 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 the download.

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 February 18 through 24 were 35, 42, 46, 47, 29, 27, and 39, with a mean of 37.9. 10.7 cm flux was 94.9, 94, 100, 95.6, 93.7, 91, and 87.9, with a mean of 93.9. Estimated planetary A indices were 29, 15, 6, 4, 4, 6, and 7, with a mean of 10.1. Estimated mid-latitude A indices were 20, 10, 5, 3, 3, 5, and 5, with a mean of 12.6.




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