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Propagation Forecast Bulletin #21 de K7RA:

from W1AW Bulletin via the ARRL on May 24, 2013
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Propagation Forecast Bulletin #21 de K7RA:

Propagation Forecast Bulletin 21 ARLP021
>From Tad Cook, K7RA
Seattle, WA May 24, 2013
To all radio amateurs

ARLP021 Propagation de K7RA

Overall, solar activity is still pretty quiet, but one positive sign was on May 16, when the daily sunspot number was 212. I eyeballed the records, and had to keep searching further and further back to find a higher sunspot number.

One year, six months and one week earlier, on November 9, 2011 the sunspot number was nearly that high, at 208. We look clear back seven years, 10 months and 12 days to July 4, 2005, another near miss at 192. To find activity beating the May 16 number we have to go back nearly a decade, to November 1, 2003 when the daily sunspot number was 277. This was way back on the downward slide of cycle 23, nine years, six months and 15 days earlier than our recent high number. Let's hope for many more days like this. That seems likely, as the peak of this solar cycle is predicted for this fall, which begins about four months from now, on Sunday, September 22.

Compared to the previous period (May 9-15) average daily sunspot numbers this week were down over 12 points to 144. Average daily solar flux sank nearly 6 points to 134.2. Geomagnetic activity was higher, with average daily planetary A index up 3.7 points to 9.7, and average daily mid-latitude A index up 4.4 points to 10.3. It should be noted that five of the eight daily geomagnetic readings which make up the A index were not recorded for May 16 at the mid- latitude observatory, so the mid-latitude A index of 12 for that day is an estimate.

The latest prediction from NOAA/USAF has solar flux at 135 on May 24-25, 130 on May 26-27, 135 on May 28-29, and then 130, 115, 105 and 110 on May 30 through June 2, 120 on June 3-5, and 125 on June 6-8, before rising to a short-term peak of 140 on June 12-13. This prediction is a bit far off, but it also shows a minimum flux value of 100 on June 26-27.

Turning to geomagnetic activity, predicted planetary A index is 15, 20, 12 and 8 on May 24-27, 5 on May 28 through June 10, and then 8, 12 and 8 on June 11-13, 5 on June 14-17, and then 15, 12, 8 and 5 on June 18-21. On June 24, a month and about one solar rotation from now, they show planetary A index rising from 5 to 15, perhaps an echo of current geomagnetic activity.

OK1HH predicts active to disturbed geomagnetic conditions May 24, quiet to active May 25, mostly quiet May 26-27, quiet to active May 28, quiet to unsettled May 29, quiet May 30, quiet to unsettled May 31 through June 1, mostly quiet June 2, quiet to unsettled June 3, quiet June 4-8, mostly quiet June 9-10, quiet to active June 11, active to disturbed June 12-13, quiet to unsettled June 14, and mostly quiet June 15-16.

The CQ World Wide WPX Contest, CW weekend begins tonight/tomorrow at 0000 UTC May 25. The geomagnetic activity predicted for this weekend may add some additional challenge to the test, which has a new set of rules. The multiplier used is the number of unique call sign prefixes of stations worked. See details at

The current geomagnetic activity is due to a May 22 M5 class solar flare, which is expected to deliver a glancing blow to our geomagnetic field today, May 24.

Jon Jones, N0JK reports that during a six meter e-layer opening last Sunday evening observed from coast to coast in North America, a rare Australia to North America opening took place. From 2355 UTC on May 19 until 0032 UTC on May 20 on CW VK4MA worked W9FF, NW0W, K9ZM, WZ8D, W9WZJ and K0GU. It appears the longest distance was to WZ8D, about 9,041 miles. N0JK believes the propagation path was via e-layer linked to trans-equatorial propagation.

Last Friday, May 17 Jim Smith, K3RTU took his backpack rig into Ridley Creek State Park in Southeast Pennsylvania (FM29). He wrote: "After some hiking I set up my Buddistick vertical and new KX3 about 1730. I tried 15 meters first, but had no luck and only heard a few stations, so I readjusted the antenna for 17 meters and after a few minutes worked Duncan, EA5ON/M with SSB and got a 54 report. Not too bad for vertical to vertical, but the QRN on his end was troublesome. Duncan told me it was raining there with lots of atmospheric noise and later contacts with Western Europe confirmed the bad weather was pretty wide spread. Then over the next two hours worked Dave VP5/W5CW (my report 59), Mario DJ2OR (55), Carolyn W5/G6WRW near Santa Fe, NM (53), Al VE7WJ (53), Joe DF9ZP (59), KB5AVE (56), and last, Mike IF9ZWA (55) on Favignana Island off the coast of Sicily. What amazed me the most was that I had good propagation both east and west of my location which I don't always find to be the case."

And finally, I just ran across a previously overlooked email from Wayne Mills, N7NG of Jackson Hole, Wyoming sent on January 4, 2013, reflecting on cycle 19. Wayne said, "I have seen all of the solar peaks since 1956. What I have to say, however, is that I had absolutely no expectation of what cycle 20 might be like. The reason was that when I was a sophomore in high school in 1958, I had NO IDEA what sunspots were.

I started working DX in 1956 with 90 watts and a low 40M dipole. I was on 20M CW ONLY. No worries about other bands, what might be open, what long paths might be open. Just listen and work what I heard.

It was just a few high school friends and me; we had very little contact with local DXers. Eventually, I ran into W6MX (Honor Roll 1955) and W6BAX, a serious DXer and learned a few things.

Soon, I put up a 2 element 20M beam, and then I had to worry about where to point it. Still, it took more than 2 years to work DXCC.

Things will never be the same."

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

Monthly propagation charts between four USA regions and twelve overseas locations are at

Sunspot numbers for May 16 through 22 were 212, 198, 146, 113, 113, 119, and 107, with a mean of 144. 10.7 cm flux was 144.7, 136.4, 132.1, 135.3, 132, 125.3, and 133.4, with a mean of 134.2. Estimated planetary A indices were 14, 9, 21, 12, 7, 7, and 12, with a mean of 9.7. Estimated mid-latitude A indices were 12, 9, 16, 11, 6, 8, and 10, with a mean of 10.3.

Source: W1AW Bulletin via the ARRL.

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