Australia’s Space Weather Services issued a geomagnetic disturbance warning at 2224 UTC on December 17. It read in part, “Two coronal mass ejections observed Dec 16 are expected to impact the Earth in sequence late Dec 18 to early Dec 19. Brief minor to major geomagnetic storm conditions may result.”

For December 18 they predicted quiet to active conditions, and on December 19 active to minor storm.

Solar activity increased over the past week, compared to the previous seven days. Average daily sunspot number on December 10-16 was 74.3, up from 48 over the previous seven days, December 3-9.

Average daily solar flux increased from 102.2 to 118.6.

Geomagnetic indices were also higher, with planetary A index going from 9.9 to 15.6, and mid-latitude A index from 6.6 to 11.3.

The latest prediction from USAF/NOAA forecasters shows predicted daily solar flux at 120 on December 18, 125 on December 19-21, 120 on December 22-23, then 115, 110, 105 and 98 on December 24-27, 95 on December 28-29, 98 on December 30-31, 100 on January 1-2, 105 on January 3, 110 on January 4-6, 115 on January 7-9, and then peaking at 130 on January 11-13 before dropping back below 100 after January 22.

Predicted planetary A index is 16, 42, 18, 10 and 8 on December 18-22, 5 on December 23-26, then 18, 15 and 10 on December 27-29, 5 on December 30-31, then 15, 20, 18 and 10 on January 1-4, 8, 20, 18 and 12 on January 5-8, and 10, 8, 18 and 25 on January 9-12. Planetary A index then quiets down to 5 on January 16-22.

The OK1HH Geomagnetic Activity Forecast says to watch for quiet to active conditions December 18, active to disturbed conditions December 19, quiet to unsettled December 20, quiet December 21-22, mostly quiet December 23, quiet December 24, quiet to active December 25-27, active to disturbed December 28, quiet to unsettled December 29, mostly quiet December 30, quiet to active December 31, active to disturbed January 1-2, quiet to unsettled January 3, mostly quiet January 4, quiet to active January 5-6, quiet to unsettled January 7, mostly quiet January 8, quiet January 9, active to disturbed January 10, and quiet to unsettled January 11.

OK1HH expects an increase in solar wind on December 16-19, 26-29, January 2-4 and 7-8. The prediction is less certain on December 16-17, 19, and 28-29.

The Geminid meteor shower always has the possibility each year of enhancing conditions for the ARRL Ten Meter Contest (due to ionized meteor trails), but this year the peak occurred after the contest, on December 14. But still, the shower was predicted to last from December 7-16.

Mark Schreiner, NK8Q, of State College, Pennsylvania sent in this report on the 160 meter contest from two weeks ago.

“I was also operating in the 160-meter contest last weekend. While I had some distractions that prevented me from putting in the full amount of time I would have liked, I did have a blast running QRP, especially on Friday night from 0100Z to 0200Z when I was camped out on 1800.35 kHz calling CQ. I had run rates like I've never seen while running QRP before (on any band!). The peak was 153 QSOs per hour in a 10 minute window, but that wasn't just a quick flurry of activity and then it was done, it kept going for about 1-1/2 hours.

“I had a 60 minute run rate of 53 Qs/Hr which is about double my normal rate. Unfortunately, I was at a birthday party on Saturday evening so wasn't able to operate during that obviously prime timeframe, but did get back on around 0400Z and stayed on through until about an hour after sunrise at 1300Z on Sunday morning when I shut down.

“I finished with over 400 QSOs and 60 multipliers with 17 hours of my QRP efforts (and thanks to all who spent time working to pull my signal out!). I was especially pleased when a station from the Virgin Islands answered my CQ! Best DX from central PA to the east was GW (Wales), to the south was SFL (South Florida) and C6 (Bahamas), to the west was AZ and OR and to the north was VY2. I've heard better conditions, but it wasn't too bad.”

Mark operated the club station at the Nittany Amateur Radio Club, with 5 W and a 160 meter half-wave inverted V antenna: http://www.nittany-arc.net/station.html


Jeff, N8II, reported on December 12: "I am in the 10 meter contest right now, conditions surprisingly good especially to the States, but openings shorter than last year although good to 7 land from 1630Z until local sunset (2200Z). I will send a report later. On a usual day there is almost no USA activity at mid-day (making you think the band is not open); there was plenty today!"

On December 17 Jeff wrote: "I just sent a report on the 10 meter contest, it was not a total collapse (in reference to N0JK comments later in today’s Solar Update - Tad), but conditions were noticeably down all day Sunday compared to Saturday and the skip zone was much longer, especially to the south in the afternoon.

“The K index was running mostly at 3 the first day and 1-2 Sunday with SFI up to 123 Sunday, but continuing the pattern I have observed recently, Saturday was actually a significantly better day.

“Friday evening, conditions were worse than I can ever remember. The band was almost totally dead as it was after 24Z Saturday evening as well. I worked only ME and two FL stations on meteor scatter Friday, the rest were all within local working range which extends out to OH (barely), CT, NY, and NJ.

“Saturday, my first QSO at 1224Z when I fired up was on CW with a French station peaking around 120 degrees vs. normal heading of 55 via F2 scatter. Sunrise was about 1220Z. I continued to work the East Coast on backscatter, Canary Islands, Czech Republic, Netherlands, and Germany all on F2 scatter except for African stations.

“At 1250Z, the first loud direct path Caribbean station was in the Virgin Islands. Around 1320 a couple of loud Quebec stations called via Es on CW. Still on scatter beaming 90-120 degrees, numerous stations in Germany, Switzerland, Croatia, and Italy were logged until finally, at 1353Z, a loud direct-path CR7 in Portugal was found on SSB and many EU QSOs followed until 1600Z when the band rapidly closed in that direction.

“The northernmost extent of the opening was Scotland, Germany, and Poland with a good number of Mediterranean area stations including Macedonia and Israel. Dutch stations were loud and numerous as well as England for a shorter time.

“Surprisingly, at 1432Z, a fairly loud US5 in the Ukraine called (never heard one in the CQWW on CW). Last year into EU lasted much longer and farther north into all of northern EU at times. BY 1600Z, stations to the west were loud and numerous which lasted all day until 2100Z when the band started to fade.

“The skip zone was the shortest around 1700-1800Z right around local noon here and just west of here. The skip zone with loud stations was as short as MS, LA, and MN aided by some Es which probably also added some loud Texans. But, the band never opened well to KS, MO, NE (one loud station only), IA, and SD.

“CA was weak at times, but never almost gone like last year and the Rocky Mountain states plus WA, OR, and AZ were easy to work as well as VE4-VE7 (Manitoba thru British Columbia).

“Signals were good to the south as well down to Brazil and Argentina, but the northern Caribbean faded out by around 1900-2000Z. I was called by Hawaii, New Zealand, and a weak QRP station in Australia, but nothing else from the Pacific was heard and I had to QRT at 2120Z before any hope of Asia might appear.

“Sunday was slow for new QSOs and propagation was worse despite better solar indices. The first sweep of SSB band was devoid of any signals. My first QSO was a OQ4 in Belgium at 1222Z on CW aided by Es to the Canadian Maritimes which lasted until past 1345Z, but activity in Canada was low (was called by PEI).

“I found few new stations in EU and had few answers to CQs. Most signals were not strong that were worked all morning. Around 1400Z was the peak of EU with Turkey, Ukraine, Poland, Czech and Slovak Republics calling in on CW.

“Backscatter to the Eastern USA/VE beaming south around 1430-1530Z was strong, but I had few callers on SSB despite some signals near S9. The northern Caribbean was also loud that time, but faded out for good by 1800Z.

“After 1520Z, EU was nearly gone working last one EI2 in Ireland at 1539Z. BY 1530Z stations in the far western USA were loud, so I turned my attention that direction with excellent signals also from Mexico where several new XE states called in on CW. By 18Z backscatter had gotten weaker and continued to worsen and only mostly deep SA stations were workable to the south. I did have decent conditions to CO/NM and farther west and worked quite a few CA stations, but OR/WA was much weaker than Saturday. The west coast was gone by 2200Z only 10 minutes past sunset and my last SA QSO was with Peru at 2225Z which ended any ionospheric propagation for the day. Of note was a QSO with VE8NSD in the NW Territories at 2049Z on SSB, my only Arctic QSO (no AK). I worked all of the provinces except for Nunavut and Yukon between both modes.

“I ended up with 140 California QSOs, 82 from Arizona, and 73 from Washington, 60 from Maryland (locals) totaling 1317 with 204 multipliers. Both QSOs and multipliers were way down from 2014, but there was plenty of activity except a bit sparse Sunday afternoon.”


David Moore sent this link to a time-lapse video from way back in 2003 of a huge solar flare. Just click on the big black space between the two blue arrows to watch: https://shar.es/1Gg1US

The snow-like artifacts were caused by radiation from the flare overloading the camera in the observatory (SOHO). Check this for more info on SOHO: http://sohowww.nascom.nasa.gov/

David also sent a link about the NRAO Very Large Array studying solar flares: http://www.sciencedaily.com/releases/2015/12/151203150131.htm

More info on the VLA: http://public.nrao.edu/explorer/vla/TheVLAExplorer.php

I like this image: http://public.nrao.edu/explorer/vla/TheVLAExplorer.php?map=ArraySite


We have a couple of reports from Jon Jones, N0JK, first regarding the recent 10 meter contest:

“The 10 meter band "collapsed" Sunday afternoon (December 13) for many stations in Central and northern South America to North America in the ARRL 10 meter contest. Steve, PJ4DX posted in his "3830" contest report that he was frustrated hearing loud PY and LU stations still running mainland USA stations Sunday afternoon and these NA stations were completely inaudible for him.”

PJ4DX is on the island of Bonaire, which lies off the coast of Venezuela in the Southern Caribbean.

Two days later, on December 16, Jon wrote: “A long lasting 6 meter Es morning opening December 16. Here in Eastern Kansas, Michigan and Ohio stations were loud including the NF8M/b 50.076 MHz in EN82 which was 599 at 1710z. It runs just 5 W to a ground plane antenna!

“Later the Es moved west and as I write stations in western Colorado and Utah are working the Pacific Northwest at 1935z.”

The beacon station that Jon mentioned in his report: http://www.nf8m.com/


For the next two weeks, even with the holidays, this bulletin will still come out on Friday, December 25 and Friday, January 1. There will be no ARRL Letter during those weeks.


For more information concerning radio propagation, see the ARRL Technical Information Service at http://arrl.org/propagation-of-rf-signals. For an explanation of the numbers used in this bulletin, see http://arrl.org/the-sun-the-earth-the-ionosphere. An archive of past propagation bulletins is at http://arrl.org/w1aw-bulletins-archive-propagation. More good information and tutorials on propagation are at http://k9la.us/.

My own archives of the NOAA/USAF daily 45 day forecast for solar flux and planetary A index are in downloadable spreadsheet format at http://bit.ly/1VOqf9B and http://bit.ly/1DcpaC5 .

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 http://arrl.org/propagation.

Instructions for starting or ending email distribution of ARRL bulletins are at http://arrl.org/bulletins.

Sunspot numbers for December 10 through 16 were 86, 77, 89, 74, 81, 64, and 49, with a mean of 48. 10.7 cm flux was 108.5, 113.7, 116.7, 122.5, 124, 118.9, and 126.2, with a mean of 102.2. Estimated planetary A indices were 23, 20, 12, 8, 22, 17, and 7, with a mean of 9.9. Estimated mid-latitude A indices were 18, 14, 8, 6, 15, 13, and 5, with a mean of 6.6.