Both the average daily sunspot numbers and solar flux were both higher for the week: Sunspot numbers up more than 3 points to 93.1 and the solar flux up by 8 points to 117.2. Geomagnetic activity was a bit lower -- with April 20 the most active day -- after a coronal hole on the Sun spewed a solar wind at high speed. The Australian government gave an alert one day prior. You can subscribe to those e-mailed warnings. If you are in Australia, the same service offers an HF radio propagation course. See here for details. The same Australian service has predicted monthly smoothed sunspot numbers and solar flux and it looks like they predict the peak of Solar Cycle 24 exactly two years from now in April 2013.

Currently there are four sunspot groups visible, and today could see a geo-magnetic disturbance from a slow-moving coronal mass ejection. Sunspot numbers for April 14-20 were 131, 124, 97, 67, 67, 76 and 90, with a mean of 93.1. The 10.7 cm flux was 118.7, 129.4, 119.2, 114.4, 111, 110.9 and 117, with a mean of 117.2. The estimated planetary A indices were 7, 6, 4, 5, 10, 6 and 16, with a mean of 7.7. The estimated mid-latitude A indices were 3, 3, 2, 2, 8, 4 and 11, with a mean of 4.7.

The latest forecast from NOAA/USAF should solar flux at 115 for April 21-24, 110 for April 25-29 and 115 again on April 30 through May 3. The predicted planetary A index is 10 and 8 for April 21-22 and 5 on April 23-27. On April 28-29, the predicted planetary A index is 7, 15 and 12.

The May issue of WorldRadio Online is now available. Check out the propagation column by K9LA on page 22, which this month concerns an unusual divergence during the recent solar cycle when correlation between solar flux and sunspot numbers seemed to decrease.

Mark Lunday, WD4ELG, of Greensboro, North Carolina, is excited about all the recent solar activity and associated propagation: “I never thought it would happen, but the sunspots are back!” Mark notes that 10 meters is open worldwide during the day, and 20 meters is open all day and night to somewhere in the world. He sends lists of DX worked from all over, all with simple antennas. Check out his blog.

Richard Kautz, KC2HZW, of Pelham, New York, is looking forward to a good sporadic-E and F-layer propagation season on 6 meters: “I have really been enjoying the renewed sunspot activity the last two months. This week, conditions on 15 meters have been excellent. Friday, April 15, I worked HS0ZIN at 1523 with 59+ signals in both directions. On Saturday, I worked VU2PAI at 1920 again with 59 signals in both directions. I also worked JE1LET at 2330. I listened to KL7LF for a while working a pile up with a great 59 signal. I modeled many of the contacts I made the last few days on W6ELprop,and while the program predicted many of the contacts were possible, in none of the cases did the predictions show signal strengths anywhere near what I experienced. I am not complaining -- it been about eight years since I worked into Southeast Asia on the higher bands and it was a real thrill.”

Oleh Kernytskyy, KD7WPJ, of Saint George, Utah, has been operating QRP CW from mountain peaks out west. He writes: “On April 16 and17, I activated Grandeur Peak (SOTA -W7/NU-065). I was able to make contacts with JE2RMH and 5N7M on 21 MHz with 10 W and a simple dipole. I also heard a lot of stations from Brazil on 28 MHz, but they all worked in the contest.”

Jeff Hartley, N8II, of West Virginia, writes on April 16: “The SFI is 129 and K 1 today and you could tell it. But first back to Monday, April 11, when I was lucky enough to be off from work. On 15 meters CW -- between 0018 and 0031 – I logged BA1KW, HS0ZBS and XV2W, great DX for us on the East Coast. Then as early as 1249, IS0GQX was 599 on 12 meters CW. P29NI running a big IOTA European pile up was easily worked on 17 meters at 1236, and JJ0NCC answered a CQ at 1309.

“Then up on 15 meters, I worked YB0NFL on SSB 59 at 1325 (quite early), along with UA0SR, UA9QM and YB9/DJ7XJ on 15 meters CW. But the biggest surprise of the day was E21EJC at 1418, and HS0ZBS and 9M2TO on 12 meters CW! Then, I was treated to more over-the-pole DX on 15 meters, VU2PAI and V85TL. I logged HS0AC on 17 meters CW at 1525 and then found Kob, E21EJC, there 10 minutes later. It doesn’t get much better than that here, unless 10 meters opens polar, which is rare. Today, the 16th, it all started with 14 Russians from all over Asia answering my CQ from 0033 thru 0115, along with HB9, EA5, BD0AH and UN7PBW on 20 meters CW.

“At 1305, I worked XV2RZ on 17 meters CW. P29VLR was running a large European pile-up and was about S3-4 here. At 1325, 12 meters was open well to Europe at 1325, with OL2011VP 599 on 12 CW, but despite a good European opening with lots of Germans logged, the band never opened to the Far East as on Monday. Ten meters started to open to Europe at 1423, and I worked 4O3A, 599+ and 15dB, but CQs yielded no answers. After a run of Europeans on 12 meters, I returned to 10 meters SSB at 1522 to find HZ1DG 57. Then I worked around the Mediterranean area on 10 meters logging Italians three IT9s, E71A and 9H5BZ. Down on 15, the band was open to most of Asia, including due north to Southeast Asia, where I worked RL9AA on CW and 9M2GET at 1634 on SSB, 59, who was running a big pile up. I also logged YC6NE and his neighbor YB6MIX at 1702. It was quite a morning!”

All times listed are UTC, unless otherwise noted.

Amateur solar observer Tad Cook, K7RA, of Seattle, Washington, provides this weekly report on solar conditions and propagation. This report also is available via W1AW every Friday, and an abbreviated version appears each Thursday in The ARRL Letter. You can find a guide to articles and programs concerning propagation here. Check here for a detailed explanation of the numbers used in this bulletin. An archive of past propagation bulletins can be found here. You can find monthly propagation charts between four USA regions and 12 overseas locations here. Readers may contact the author via e-mail.