Tad Cook, K7RA, of Seattle, Washington, reports for this week’s ARRL Propagation Bulletin:

I am writing this, my penultimate bulletin of 2022, about seven hours after the start of Winter Solstice in the Northern Hemisphere on Wednesday December 21, 2022, at 2147 UTC. It is very cold in Seattle, about 17 degrees Fahrenheit on the longest night of the year.

Solar activity was down a bit from the previous week, although it was one of those odd occasions when average daily sunspot numbers and solar flux changed in opposite directions.

Average daily sunspot number declined from 136.9 to 124.1, while solar flux rose from 150 to 153.8.

Geomagnetic indicators were a bit lower, with average planetary A index changing from 7.7 to 6.7, and middle latitude numbers from 6 to 5.1.

Due to missing data, I had to fudge one of the numbers (the December 16 middle latitude A index), which I pegged at 7 by eyeballing trends.

Predicted solar flux appears to reach a short-term peak of 160 on January 4 – 7, 2023. Starting December 22, 2022, the forecast shows 140 and 135 through December 23; 130 on December 24 – 25; 135 on December 26 – 28; 130, 135, and 138 on December 29 – 31; 140, 150, and 155 on January 1 – 3, 2023; 160 on January 4 – 7; 158, 156, 154, 154, and 152 on January 8 – 12; 150 on January 13 – 15; 145, 130, and 120 on January 16 – 18; 118 on January 19 – 20; and 120, 125, and 127 on January 21 – 23.

Predicted planetary A index is 12, 8, 5, 14, and 10 on December 22 – 26; 8, 5, 12, 10, and 12 on December 27 – 31; 8, 5, and 18 on January 1 – 3, 2023; 10 on January 4 – 5; 8, 10, and 6 on January 6 – 8; 5 on January 9 – 14; 12, 10, and 20 on January 15 – 17; 12, 8, 5, and 18 on January 18 – 21; and 20 on January 22 – 24.

In Friday’s bulletin look for a 6-meter report from Jon Jones, N0JK, the columnist of “The World Above 50 MHz” in QST magazine, and any other interesting observations you and others may send my way.

Sunspot numbers for December 15 through 21, 2022 were 140, 108, 139, 128, 132, 119, and 103, with a mean of 124.1. The 10.7-centimeter flux was 165.9, 163.1, 154.6, 155, 6, 152.4, 146.4, and 138.7, with a mean of 153.8. Estimated planetary A indexes were 5, 9, 3, 4, 11, 6, and 9, with a mean of 6.7. Middle latitude A index was 4, 7, 2, 2, 9, 5, and 7, with a mean of 5.1.

Send your tips, questions, or comments to k7ra@arrl.net.

A comprehensive K7RA Solar Update is posted Fridays on the ARRL website. For more information concerning radio propagation, visit the ARRL Technical Information Service, read “What the Numbers Mean…” and check out the Propagation Page of Carl Luetzelschwab, K9LA.

A propagation bulletin archive is available. For customizable propagation charts, visit the VOACAP Online for Ham Radio website.

Share your reports and observations.

Tad Cook, K7RA, of Seattle, Washington, reports for this week’s ARRL Propagation Bulletin, ARLP050:

Heightened sunspot activity over the past week no doubt produced the great conditions during last weekend’s ARRL 10-Meter Contest.

Compared to the previous 7 days, average daily sunspot numbers jumped from 85 to 136.9, while solar flux averages increased from 137.5 to 150.

Geomagnetic indicators were lower, with planetary A index decreasing from 14.4 to 7.7, and middle latitude A index decreasing from 9.1 to 6.

Higher sunspot numbers and lower geomagnetic indicators are an ideal combination for favorable HF propagation.

New sunspots appeared every day except December 12, with one new sunspot on December 8, another on December 9, three more on December 10, another on December 13, and one more on December 14.

The latest prediction from the United States Air Force (USAF) via National Oceanic and Atmospheric Administration (NOAA) shows solar flux at 164, 160, 158, and 156 on December 15 – 18; 154 on December 19 – 20; 150 and 125 on December 21 – 22; 120 on December 23 – 28; 125, 130, and 135 on December 29 – 31; 145 on January 1 – 8; 140, 130, 125, and 120 on January 9 – 12, and 115 on January 13 – 18.

Predicted planetary A index is 5 on December 15 – 17; 8 on December 18 – 20; 12, 20, 15, and 12 on December 21 – 22; 20 on December 25 – 28; 12, 10, 12, 8, 5, and 18 on December 29 through January 3; 10 on January 4 – 5; 8 on January 6; 5 on January 7 – 14, and 10 on January 15 – 16.

In Friday’s bulletin we will have reports from the 10-meter contest and some 6-meter observations.

Sunspot numbers for December 8 through 14, 2022, were 115, 116, 111, 141, 142, 159, and 174, with a mean of 136.9. The 10.7-centimeter flux was 143, 149.1, 141.7, 147,7, 150.8, 153, and 164.7, with a mean of 150. Estimated planetary A indices were 11, 11, 8, 10, 6, 4, and 4, with a mean of 7.7. Middle latitude A index was 9, 9, 6, 7, 5, 3, and 3, with a mean of 6.

Send your tips, questions, or comments to k7ra@arrl.net.

A comprehensive K7RA Solar Update is posted Fridays on the ARRL website. For more information concerning radio propagation, visit the ARRL Technical Information Service, read “What the Numbers Mean…” and check out the Propagation Page of Carl Luetzelschwab, K9LA.

A propagation bulletin archive is available. For customizable propagation charts, visit the VOACAP Online for Ham Radio website.

Share your reports and observations.

A few pictures provided by James KK7CLU.

The K7RA Solar Update

Tad Cook, K7RA, of Seattle, Washington, reports for this week’s ARRL Propagation Bulletin:

No new sunspots appeared over the past reporting week, November 24 – 30. But sunspots were visible every day.

Sunspot numbers and solar flux declined, with the average daily sunspot number dropping from 66 to 46, and average daily solar flux from 116.5 to 108.3.

Solar wind streams from coronal holes kept geomagnetic indicators active, with average daily planetary A index jumping from 5.1 to 18.6, and middle latitude A index from 3.4 to 14.

On Wednesday, November 30, the magnetometer at Fairbanks, Alaska, showed the college A index at 54, which is the highest value over the past month. No doubt this produced aurora.

The current prediction from Wednesday night has solar flux reaching a peak of 130 on December 12, rather than the 135 recently predicted.

Look for flux values of 115, 115, and 120 on December 1 – 3; 125 on December 4 – 10; 130, 115, and 110 on December 11 – 13; 105 on December 14 – 17; 100 on December 18 – 23; 95, 105, and 110 on December 24 – 26; 115 on December 27 – 30, and 120 on December 31.

The planetary A index prediction is 25, 20, 10, 12, and 8 on December 1 – 5; 5 on December 6 – 7; 8 on December 8 – 9; 5 on December 10 – 16; 10 on December 17 – 18; 5 on December 19 – 21; 20, 15, 12, and 10 on December 22 – 25; and 15, 18, 10, 18, and 10 on December 26 – 30.

Solar wind news:

https://bit.ly/3EVkeUW

Sunspot numbers for November 24 through 30 were 61, 55, 60, 56, 52, 25, and 12, with a mean of 46. The 10.7-centimeter flux was 109.7, 108.5, 107.1, 107.2, 107, 107.9, and 111, with a mean of 108.3. Estimated planetary A indices were 6, 20, 16, 15, 24, 25, and 24, with a mean of 18.6. Middle latitude A index was 6, 15, 12, 10, 18, 20, and 17, with a mean of 14.

Send your tips, questions, or comments to k7ra@arrl.net.

A comprehensive K7RA Solar Update is posted Fridays on the ARRL website. For more information concerning radio propagation, visit the ARRL Technical Information Service, read “What the Numbers Mean…” and check out the Propagation Page of Carl Luetzelschwab, K9LA.

A propagation bulletin archive is available. For customizable propagation charts, visit the VOACAP Online for Ham Radio website.

Share your reports and observations.