Tad Cook, K7RA, Seattle, reports: There were no zero-sunspot days over the December 21-27 reporting week. Then, on Thursday, December 28, no sunspots were visible. So far in 2017, there have been 102 days with no sunspots, or 28%.

The average daily sunspot number was 17.4, up from 2.3 over the previous 7-day reporting period. The previous week had such a low average because only 1 day out of that week had any sunspots at all — December 20, with a sunspot number of 16.

The average daily solar flux was 74.6, up from 71.5 the previous week.

The average daily planetary A index declined from 9.4 to 7.1, while the average mid-latitude A index dipped from 6.1 to 5.7.

We probably will not observe a return of any sunspots at least until January 5, when the predicted solar flux is expected to increase slightly, from 68 to 72.

Predicted solar flux for the next 45 days is 70 on December 29-31; 68 on January 1-4; 72 on January 5-12; 74 on January 13; 75 on January 14-25; 74 on January 26; 72 on January 27-February 8; 74 on February 9, and 75 on February 10-11.

The predicted planetary A index is 5, 5, 10, 25, 15, and 8 on December 29-January 3; 5 on January 4-6; 10, 12, and 6 on January 7-9; 5 on January 10-12; then 22, 16, 20, 16, 10, 8, and 5 on January 13-19; 12 on January 20-21; 8 on January 22; 5 on January 23-26; 10, 25, 15, and 10 on January 27-30; 5 on January 31-February 2; 10, 12, and 6 on February 3-5; 5 on February 6-8, and 22, 16, and 6 on February 9-11.

The geomagnetic activity forecast for December 29-January 24 from F.K. Janda, OK1HH: Geomagnetic field will be:

• Quiet on December 30, January 5, 11, 17-18, 23-24

• Mostly quiet on December 29, January 4, 6, 19,

• Quiet to unsettled on January 7-8, 10, 16,

• Quiet to active on December 31, January 2-3, 12, 14-15, 22

• Active to disturbed on January 1, 9, (13, 20-21)

• Amplifications of the solar wind from coronal holes are expected on December 31, January 1-3, (6-8,) 10-13, 19-20, (21-22).

Figures in parentheses indicate a lower probability of activity enhancement.

Jeff Hartley, N8II of Shepherdstown, West Virginia (FM19ck), reported on December 22:

“We had some excellent low-band conditions on the evenings of December 20-21 allowing QSOs with S01WS Western Sahara, Finland, Sweden, European Russia, Lithuania, Romania, and Ukraine on 160, with best signals mostly around 2400 and 0100. On 80, Russia, Latvia, Lithuania, Greece, Poland, Hungary, Slovenia, and Romania were worked. Many signals on 80 were at least S-9, as were several on 160.

“On December 22, 15 opened late to Europe, allowing a very solid S-9 QSO with EA7ATX at 1603 on 15 phone, followed by S-9 + 15 dB with MI5AFK in Northern Ireland. England and VO1CAL in Newfoundland were also worked on SSB and Hungary on CW. There could have been some sporadic E involved, not sure.”

Dr. Tamitha Skov is featured in the first 2018 issue of Popular Science:

Her report from last weekend. The latest report should be posted soon.

For more information concerning radio propagation, see the ARRL Technical Information Service at. Here is an explanation of the numbers used in this bulletin. An archive of past propagation bulletins is on the ARRL website. More information and tutorials on propagation are on the website of Carl, K9LA. The ARRL website also offers monthly propagation charts between four US regions and 12 overseas locations.

Instructions for starting or ending e-mail distribution of ARRL bulletins.

Sunspot numbers for December 21-27, 2017 were 18, 18, 22, 22, 17, 14, and 11, with a mean of 17.4. The 10.7-centimeter flux was 76, 75.3, 76.2, 76.1, 75.7, 71.8, and 71, with a mean of 74.6. Estimated planetary A indices were 3, 2, 5, 12, 10, 11, and 7, with a mean of 7.1. Estimated mid-latitude A indices were 2, 2, 4, 9, 9, 8, and 6, with a mean of 5.7.