Solar activity revived over the past week, with a big increase in sunspot numbers. On Friday, April 20, the daily sunspot number reached 162; four days later on April 24, the number reached 169. This level of activity has not been seen since last fall, when the daily sunspot number reached 173 on September 16, 184 on October 21 and 208 on November 9.

The average daily sunspot numbers more than doubled over the previous week’s average, rising 73 points to 144.7, while the average daily solar flux was 133.9, an increase of nearly 29 points. Sunspot numbers for April 19-25 were 122, 162, 147, 118, 158, 169 and 137, with a mean of 144.7. The 10.7 cm flux was 137.8, 141.7, 149.1, 147.9, 141.8, 133.6 and 127.2, with a mean of 133.9. The estimated planetary A indices were 5, 7, 6, 7, 23, 35 and 21, with a mean of 14.9. The estimated mid-latitude A indices were 5, 7, 6, 7, 21, 30 and 18, with a mean of 13.4.

Associated with all this was a rise in geomagnetic activity, peaking with a planetary A index of 35 on Tuesday, April 24. The geomagnetic activity increase was due to several solar flares launched from new sunspots. The latest forecast shows solar flux of 115 on April 27, 110 on April 28, 105 on April 29-30, 100 on May 1-2, 95 on May 3, 105 on May 4, 110 on May 5-6, 115 on May 7-8, 120 on May 9, 130 on May 10-12, 135 on May 13, 140 on May 14-17, 135 on May 18-21, followed by 130, 125, 120, 115 and 110 on May 22-26, and then back down to 105 on May 27-31. Predictions for planetary A index are 10 on April 27, 5 on April 28-May 1, 8 on May 2, 5 on May 3-7, 8, 12, 15 and 10 on May 8-11, 5 on May 12-19, 12 and 10 on May 20-21, and 5 on May 27-31.

Jim White, WD0E, worked FK8CP (New Caledonia) on April 26. He wrote: “I just worked FK8CP on 6 meters SSB from DM79, about 35 miles southeast of Denver at 0027 on April 26 – an amazing 7131 mile path. For an hour before I worked him, there were spots of him from Southern California on DX Sherlock (see http://www.vhfdx.info/spots/), but not much in the way of sporadic E between here and Southern California. This must have been an Es cloud just off the coast of Southern California linked to trans-equatorial propagation. He was in and out of the noise, but we heard him for about 20 minutes off and on. Looking at it again, I think the E cloud was right over Southern California, not off the coast. For the geometry to work it had to have been there, I think. I’m hearing a bunch of Hawaiian stations into the West Coast right now with E clouds over Mexico and Kansas. We are listening and hoping we get that double link into Hawaii tonight!”

Jeff Hartley, N8II, of Shepherdstown, West Virginia, sent in an interesting report: “It is interesting to note that 10 meters is far from dead and propagation seems to pick up out west around sunset on 10 and 12 meters. The SFI today (Sunday, April 22) has spiked up to 142. Yesterday (April 21), 10 meters sounded very similar to several days before in the 2300 hour when the flux was lower. There have been some very loud signals from South America up until about 0020 most days, with sunset around 2350. I have also heard loud W6s in Southern California and a few Australian and New Zealand stations, too. I worked YJ0VK on 12 meters with a weak signal.

“On Saturday evening (April 21), 12 meters opened to NL7G and FO5WBB, along with the 10 meter propagation mentioned above. Conditions to Japan were excellent on 15 meters around sunset (2400) with many loud Japanese stations as loud as S9 (above-normal for us near DC). TO3X was loud running a 15 meter phone pile-up from St Barts at 0015. There were also Japanese stations on 17 meters, as well as Zone 19 Asiatic Russians. Twenty meters was not open well to Japan at the same time, but RK9LWA/9 had a S7 signal from a rare RDA (refers to the Russian Districts Award). Thirty meters has been in excellent shape to Europe around our sunset, with HA9RT S9 +20 dB on my dipole just after 2400 on April 21 and MI0GRG S9 +10 dB running a big pile up at 0004.

“Monday (April 23) was very unusual, with disturbed conditions in the morning; most of the DX action was on 15 meters. I started off at 1357 getting YB4GU in response to my CQ, S8 on Sumatra, who was running 100 W and a dipole and very fluttery. My next QSO was the opposite end of Indonesia -- YC9BEC on Bali with very little flutter. Signals from all over Europe were fluttery and peaking north to about 20 degrees; even A61ZX and 5B8AD on Cyprus were peaking around 20 degrees. I cannot recall such an extreme skew to the north on signals so far south, normal headings are 45-50 degrees. Conditions continued about the same for an hour working on CW, RU9HM, RU4SO, UA3EDP/6, RU1QD and RT3I, all peaking north. At 1543, 5Q4B in Denmark on 15 SSB was best due north, fading over 10 dB down to about S2 during our QSO.”

Note that Jeff made a comment about disturbed conditions on April 23. Checking here, we see that April 23-25 had high A index readings at all latitudes. Interesting comparing April 24-25, where we see mid-latitude and planetary A index decrease and high latitude values increase over the two days.

Ever wonder what is going on in Sunspot, New Mexico? Check out this article from CNET.

Rich Zwerko, K1HTV, of Amissville, Virginia, sent a response to the advice from Carl Luetzelschwab, K9LA, that was in last week’s Solar Update: “Well, today (April 21) --  a day before my 70th birthday -- I followed your advice. After breakfast I went down to the K1HTV shack, got on 20 meters RTTY with 80 W and worked YJ0VK for digital country #275. Later in the morning, around 1530 with my barefoot K3 and with the A3S tri-bander, I started to hunt for some DX on 15 meters. I worked a number of 4X/4Z stations in Israel in the Holyland contest. Swinging the beam north, HS0AC on 15 meters CW was quickly added to the K1HTV log. This was followed by two more stations in Thailand and two in Indonesia, all on SSB. Fifteen meters RTTY produced QSOs with EY7AD, SU9VB and VU2NKS. I also worked Brad, FO8WBB (formerly FO/N6JA), on 12 meters CW at 1719. HF conditions were so good that I worked all six continents in less than 45 minutes!

“On 10 meters, D2QV had a nice CW signal from Angola. Pointing the beam east, I also worked a number of European stations. Around 1755, I heard 9M2IDJ on 28.447 on SSB via this same skewed path over Africa. Last November, I worked Masa on 10 meters CW during an afternoon opening on this same skewed path for #331 on 10 meters CW with 100 W; my last 15 meter SSB over-the-pole QSO today was with YB1ALL at 1830. Gus reported that it was 1:30 AM local Indonesian time. Not bad for 15 meter propagation.

“Last Sunday (April 15) produced 50 MHz QSOs via an Es-to-TEP opening to the Caribbean and South America. I heard 14 stations (3 were beacons) in Uruguay, Argentina, Brazil, Puerto Rico and the Dominican Republic and worked seven of them with 100 W. But I got on the air 15 minutes too late, missing CP6UA in Bolivia, the last country I need on continental South America. Bernie, W3UR, and Dave, N3DB, were on the ball and worked the Bolivian station. As they say, ‘you snooze, you lose.’ I hope that there is a next time and another path to Bolivia before Old Sol goes to sleep and Solar Cycle 24 is history.”

Scott Bidstrup, TI3/W7RI, sent this article on the Sun’s magnetic polarity.

Jon Pollock, K0ZN, of De Soto, Kansas, had this to share: “Wow! This is like the good old days in the cycle peak from the mid1980s! The higher bands open until nearly midnight. I was on 17 meters CW about 10-11:30 PM CST Saturday night (April 21). Operations started with a QSO and ragchew with K7URU in Spokane, Washington. Signals were very good for about 35 or so minutes and we had a nice chat. Then the signals started building up to well over S9, clear indications the Gray Line was approaching, and then bingo! The band crashed and signals faded to nothing. Within about 1-2 minutes the band was dead, no signals. About five minutes later, several very strong signals suddenly showed up and the band had many signals. One was a pile-up of European stations and the other was a station in the Canary Islands running about 10 dB over S-9! The Europeans and the Spanish station lasted about 10 to 15 minutes, and then totally disappeared, but the Western Pacific came in strong. I ended up working stations in New Caledonia, New Zealand and then Argentina. All of them had strong signals, with the ZL running way over S-9.

“This is the crazy, fun stuff at the top of a sunspot cycle, with all kinds of DX on the upper bands at night. The funny thing about 17 meters was that there were no phone stations at all; all the activity on 17 meters was CW in the lower end of the band. Classic conditions. The band had a very low noise floor and was very quiet and very long skip. I could not hear any stateside stations. This is cool when it happens, but the sudden, short, appearance of the European stations at about 11 PM CST was some really ‘kinky’ propagation. I wonder what kind of prop that was and whether it was long or short path. I kind of suspect it may have been long path or ionospheric ducting.”

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 and 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.