Conditions were favorable over Field Day weekend, with the exception of a brief period where planetary K index was at 5 on Saturday night.

There were five new sunspot groups on June 23, two more on June 24, another on June 26, and another on June 27.

Average daily sunspot numbers were up, and solar flux was down.

The average daily sunspot number rose from 143 to 170, and the average daily solar flux declined slightly from 165.4 to 160.3.

This was unexpected because we normally see these values track together.

Predicted solar flux is 155 on June 29; 150 on June 30 through July 4; 145 on July 5; 135 on July 6 – 8; 145, 155, 160, 165, and 170 on July 9 – 13; 175 on July 14 – 18; 170 on July 19 – 21; 160, 150, 145, 145, 140, and 135 on July 22 – 27, and 130 on July 28 – 31.

Predicted planetary A index is 5 on June 29 – 30; 15 and 10 on July 1 – 2; 5 on July 3 – 7; 12 and 8 on July 8 – 9; 5 on July 10 – 11; a stormy 20 and 30 on July 12 – 13; 8 on July 14 – 23; 12 on July 24 – 25, and 8 on July 26 – 27.

Read about the cycle peak and see images at https://bit.ly/3ps6iOI.

Check out a useful glossary for space weather terms at https://bit.ly/3XuimeQ.

Sunspot numbers for June 22 – 28, 2023, were 176, 194, 200, 180, 158, 141, and 141, with a mean of 170. 10.7-centimeter flux was 173.2, 169.7, 160.8, 154.8, 157.7, 151.2, and 154.9, with a mean of 160.3. Estimated planetary A indices were 8, 9, 16, 15, 11, 8, and 8, with a mean of 10.7. Middle latitude A index was 8, 9, 16, 10, 11, 7, and 8, with a mean of 9.9.

Sunspot numbers and solar flux rose this week. There were two new sunspot groups on June 15, another on June 17, one more on June 18, three more on June 19, two more on June 20, and another on June 21.

The average daily sunspot number increased from 122 to 143, and the average daily solar flux rose from 154.8 to 165.4.

The average daily planetary A index jumped from 5.7 to 15.4, while the middle latitude numbers increased from 6.7 to 13.1.

Predicted solar flux is 175, 180, and 180 on June 22 – 24; 185 on June 25 – 27; 180 on June 28; 175 on June 29 through July 1; 180 on July 2 – 3; 175 on July 4 – 5; 170 on July 6 – 10; 165, 160, and 160 on July 11 – 13; 165, 160, and 160 on July 14 – 16; 155, 160, and 160 on July 17 – 19, and 165 on July 20 – 24.

Predicted planetary A index is 12, 15, 10, and 8 on June 22 – 25; 5, 5, and 12 on June 26 – 28; 5, 5, and 12 again on June 29 through July 1; 8 on July 2; 5 on July 3 – 7; 12 on July 8; 5 on July 9 – 11; 20 and 30 on July 12 – 13; 8 on July 14 – 15, and 12 on July 16 – 17.

These predictions are from forecasters Reilly and Kiser of the US Air Force 557th Weather Wing at Offutt Air Force Base, Nebraska. See https://bit.ly/3qRNJnr for more details.

So, what does this forecast show for ARRL Field Day this weekend?

Geomagnetic numbers are a bit more unsettled than what was shown in last week’s bulletin, which had an A index of 5 for Friday through Sunday. The latest shows 15, 10, and 8. Predicted solar flux looks excellent at 180, 180, and 185.

Of course, Field Day does not begin until Saturday morning, but here is data for the day prior.

Watch a video on the X1.1 solar flare at https://bit.ly/3CI0OCA.

There was another report from South Asia regarding solar flares as some sort of existential threat.

Don’t worry, there was nothing terrifying about what they reported, but there is a nice description of what the NASA-ESA Solar and Heliospheric Observatory (SOHO) does to monitor it at https://bit.ly/444VhSk. Visit SOHO’s website at https://soho.nascom.nasa.gov.

Look for an updated forecast for ARRL Field Day in Friday’s bulletin.

Sunspot numbers for June 15 – 21 were 112, 120, 110, 133, 181, 155, and 190, with a mean of 143. The 10.7-centimeter flux was 153.1, 157.2, 158.1, 164.1, 168.8, 180.1, and 176.4, with a mean of 165.4. Estimated planetary A indices were 24, 38, 8, 10, 10, 10, and 8, with a mean of 15.4. Middle latitude A index was 17, 24, 8, 12, 9, 13, and 9, with a mean of 13.1.

Solar activity declined this week, with average daily sunspot numbers dropping from 139 to 122, and the average daily solar flux decreasing from 166.8 to 154.8. This contrasts the current reporting week of June 8 – 14with the previous 7 days.

The average daily planetary A index decreased from 7.3 to 5.7, and average daily middle latitude A index from 8.6 to 6.7.

On June 14, spaceweather.com reported two new sunspot groups emerging across the sun’s southeastern horizon.

Forecasters Gervase and Kiser of the U.S. Air Force predict that the solar flux will be 150 on June 15 – 16; 155 on June 17 – 18; 150, 155, 155, and 165 on June 19 – 22; 170 on June 23 – 25; 168, 165, and 162 on June 26 – 28; 160 on June 29 through July 4; 165 on July 5; 170 on July 6 – 8; 155, 157, 153, and 160 on July 9 – 12; 150 on July 13 – 14, and 155 on July 15 – 17.

Predicted planetary A index is 8, 14, 10, and 8 on June 15 – 18; 5, 5, and 8 on June 19 – 21; 5 on June 22 – 26; 12 on June 27 – 28; 5 on June 29 – 30; 12 and 8 on July 1 – 2; 5 on July 3 – 7; 12 on July 8 – 10; 5, 5, and 12 on July 11 – 13, and 10 on July 14 – 15.

These predictions look great for ARRL Field Day (June 24 – 25) because solar flux peaks at 170 on June 23 – 25, and the predicted planetary A index is a nice, quiet 5 on June 22 – 26. Next week, we will present an updated forecast just prior to Field Day weekend.

Follow the link below for an image of the ISS over a sunspot:

https://bit.ly/3NgsByW

This link shows the same, but in video format:

https://bit.ly/43Em3B1

Check out this link for a study of the sun’s coldest region:

https://bit.ly/3X6ErQu

More sunspots can be seen at the following link:

https://bit.ly/3Nt5Ys6

Sunspot numbers for June 8 – 14, 2023, were 149, 152, 116, 116, 116, 98, and 107, with a mean of 122. The 10.7-centimeter flux was 168.5, 164.3, 161.2, 153.8, 146.1, 146.3, and 143.5, with a mean of 154.8. Estimated planetary A indices were 5, 4, 5, 9, 6, 6, and 5, with a mean of 5.7. Middle latitude A index was 6, 6, 4, 10, 8, 8, and 5, with a mean of 6.7.

Solar activity was up this week, with the average daily sunspot number increasing from 133.7 to 139, and the average daily solar flux increasing from 155.3 to 166.8.

Average daily planetary A index stayed the same at 7.3, and average middle latitude A index went from 7.9 to 8.6.

Predicted solar flux doesn’t show any improvement, with peaks at 170 on June 8 and again on June 23 – 25.

The forecast shows 170 on June 8; 165 on June 9 – 11; 160, 155, and 155 on June 12 – 14, then 145 and 150 on June 15 – 16; 155 on June 17 – 20, then 160 and 165 on June 21 – 22; 170 on June 23 – 25, then 168, 165, and 162 on June 26 – 28; 160 on June 29 through July 4, then 155, 150, and 145 on July 5 – 7.

Predicted planetary A index is 12, 8, 5, 10, and 8 on June 8 – 12; 5 on June 13 – 17, then 22, 15, 12, and 10 on June 18 – 21; 5 on June 22 – 26, then 10, 12, 5, and 5 on June 27 – 30, then 8, 12, and 8 on July 1 – 3, and 5 on July 4 – 7.

In some previous bulletins, I observed 10-meter propagation with FT8 into Florida from my QTH in Seattle, and into Mexico at a similar distance.

Recently on 10 meters, propagation has been into VK/ZL and North America, and mostly into southern California, Nevada, Utah, and Arizona. There is some seasonal variation.

Sunspot numbers for June 1 through 7, 2023, were 143, 147, 112, 110, 151, 133, and 177, with a mean of 139. 10.7-centimeter flux was 163.9, 162.3, 164.6, 168.3, 169.2, 171.8, and 167.2, with a mean of 166.8. Estimated planetary A indices were 13, 5, 5, 11, 5, 7, and 5, with a mean of 7.3. Middle latitude A index was 14, 8, 5, 11, 6, 10, and 6, with a mean of 8.6.

Both the average daily sunspot numbers and solar flux increased this week. Average daily sunspot numbers rose from 118.6 to 133.4, while average solar flux went from 143.2 to 161.2.

Geomagnetic indicators were more active. Average daily planetary A index went from 9.6 to 17.1, while average middle latitude A index rose from 9.6 to 14.4.

Predicted solar flux is 160 on May 25 – 26; 165 on May 27; 160 on May 28; 155 on May 29 – 30; 160 and 150 on May 31 and June 1; 155 on June 2 – 4; 160, 165, 160, 155, and 150 on June 5 – 9; 145 on June 10 – 11; 150 on June 12; 155 on June 13 – 14; 160 on June 15; 165 on June 16 – 17; 160, 155, and 150 on June 18 – 20; 155 on June 21 – 22, then 160, 165, and 160 on June 23 – 25.

Predicted planetary A index is 12, 15, 8, 5, and 8 on May 25 – 29; 5 on May 30 through June 1; 16, 8, 10, and 8 on June 2 – 5; 5 on June 6 – 15, then 12, 10, 5, 18, 22, 15, and 10 on June 16 – 22.

Check out a video of the beautiful auroras explained here:

https://tinyurl.com/2zxdmpu6

Check out sunspot images at these links:

https://tinyurl.com/muaakxn9

https://www.popsci.com/science/sun-images-powerful-solar-telescope/ Sunspot numbers for May 18 through 24, 2023, were 121, 155, 138, 140, 97, 130, and 153, with a mean of 133.4. 10.7-centimeter flux was 150.6, 164.6, 169.6, 163.4, 161.5, 154.9, and 164.1, with a mean of 161.2. Estimated planetary A indices were 3, 9, 35, 28, 21, 12, and 12, with a mean of 17.1. Middle latitude A index was 8, 10, 26, 19, 17, 11, and 10, with a mean of 14.4.

Many thanks to all that have checked into the Sunday night nets over this past season. The net will be on vacation until October 1, 2023. Meanwhile keep checking the web page for any updates to the repeater and enjoy your summer and early fall. See you all next October!

This reporting week, May 11 – 17, the average daily sunspot number was marginally lower at 118.6 compared to 119.3 last week.

The average daily solar flux dropped from 167.8 to 143.2.

Geomagnetic indicators were quieter, with both planetary and middle latitude A index at 9.6. Last week the two numbers were 15.1 and 11.9.

10.7-centimeter solar flux is forecast to peak at 165 on June 8.

The predicted solar flux numbers are 140 and 138 on May 18 – 19; 135 on May 20 – 21; 130 on May 22 – 24, then 154, 140, and 145 on May 25 – 27; 155 on May 28 – 30; 160 on May 31 and June 1; 155 on June 2 – 3; 160 on June 4 – 7, then 165, 160, 150, 145, and 150 on June 8 – 12, then 155 on June 13 – 17.

Predicted planetary A index is 5 on May 18 – 19; 8 on May 20 – 21; 5 on May 22 – 23, then 12, 15, and 15 on May 24 – 26; 10, 10, and 8 on May 27 – 29; 5 on May 30 through June 1, then 16, 12, 16, and 12 on June 2 – 5; 8 on June 6 – 8, and 5 on June 9 – 18.

Check out NASA’s sunspot picture from May 17 at https://bit.ly/458DrPw.

Check out a video of the recent solar eruption at https://www.youtube.com/watch?v=Rm7M5pqjCgY.

Read about how the solar flare caused a radio blackout at https://bit.ly/434c5bw.

Read about a solar storm threat at https://bit.ly/3pSK4p2.

Sunspot numbers for May 11 through 17, 2023, were 152, 134, 120, 109, 103, 106, and 106, with a mean of 118.6. 10.7-centimeter flux was 163.4, 149.1, 143.8, 139.7, 134.5, 134.3, and 137.9, with a mean of 143.2. Estimated planetary A indices were 9, 19, 13, 8, 6, 8, and 4, with a mean of 9.6. Middle latitude A index was 10, 15, 12, 9, 6, 10, and 5, with a mean of 9.6.

There was a modest increase in solar activity this reporting week, May 4 – 10.

Average daily sunspot numbers nudged up from 114 to 119.3, and average daily solar flux went up from 151.5 to 167.1.

Average daily planetary A index changed from 13.6 to 15.1, and average middle latitude A index remained the same at 11.9.

Predicted solar flux is 170, 168, 166, 162, and 160 on May 11 – 15; 162 on May 16 – 17; 155 on May 18 – 21; 150 on May 22; 145 on May 23 – 25, then 140 and 145 on May 26 – 27; 155 on May 29 – 30; 160 on May 31 through June 1; 155 on June 2 – 3; 160 on June 4 – 7, then 165, 160, and 150 on June 8 – 10.

Predicted planetary A index is 46, 30, 12, and 8 on May 11 – 14; 5 on May 15 – 22, then 12 and 20 on May 23 – 24; 15 on May 25 – 26; 10 on May 27 – 28; 8 on May 29; 5 on May 30 through June 1, then 16, 12, 16, and 12 on June 2 – 5; 8 on June 6 – 8, and 5 on June 9 – 13.

Read about possible geomagnetic stormy space weather at:

https://www.space.com/sun-reverse-sunspot-auroras-supercharge.

Sunspot numbers for May 4 through 10, 2023, were 139, 90, 99, 99, 103, 151, and 154, with a mean of 119.3. 10.7-centimeter flux was 162, 161.9, 151.8, 157.2, 171.9, 194.7, and 170.1, with a mean of 167.1. Estimated planetary A indices were 6, 5, 30, 9, 16, 14, and 26, with a mean of 15.1. Middle latitude A index was 7, 4, 21, 8, 13, 11, and 19, with a mean of 11.9

At 0134 UTC on April 27, The Australian Space Weather Forecasting Centre of the Australian Bureau of Meteorology issued a geomagnetic disturbance warning, stating, “An equatorial coronal hole is currently elevating solar wind speeds. Combined with the anticipated impact from a recent CME on April 27, geomagnetic activity is expected to be at G0-G1 levels over April 27 – 28, with a slight chance of an isolated period of G2.”

Solar and geomagnetic indicators moved in opposite directions this week. Average daily sunspot numbers over April 20 – 26 made a dramatic drop from 146.9 to 91.4, and average daily solar flux dropped from 164.5 to 139.4.

Average daily planetary A index more than tripled from 8.1 to 26.9, while average middle latitude A index more than doubled from 7.3 to 15.6.

Solar wind and explosions caused all of this grief.

Spaceweather.com reported that on April 21, a large magnetic filament on the sun exploded and hurled debris toward Earth.

Later, they reported that on April 23, at 1737 UTC a CME hit Earth, which sparked a severe G4-class geomagnetic storm. Aurora was visible as far south as southern New Mexico and Texas.

The planetary K index went as high as 8 over April 23 – 24.

Predicted solar flux over the next month is 135 on April 27 – 30; 140 on May 1 – 6, then 145, 150, 155, 160, and 165 on May 7 – 11; 170 on May 12 – 13, then 165, 160, 155, 150, 145, and 140 on May 14 – 19; 135 on May 20 – 21; 130 and 125 on May 22 – 23; 120 on May 24 – 25, and 125, 130, and 135 on May 26 – 28.

Predicted planetary A index is 18, 25, and 12 on April 27 – 29; 8 on April 30 through May 3, then 10, 8, 12, and 10 on May 4 – 7; 8 on May 8 – 9, then 5, 5, and 12 on May 10 – 12; 5 on May 13 – 15; 8 on May 16 – 17; 5 on May 18 – 22, then 15 and 18 on May 23 – 34, and 15 on May 25 – 27.

Here is a link to the aurora as observed in China:

https://bit.ly/41KyY3w

Here is a link to explaining the aurora:

https://bit.ly/3n7ROm2

Sunspot numbers for April 20 through 26, 2023, were 97, 114, 87, 86, 88, 87, and 81, with a mean of 91.4. 10.7-centimeter flux was 147, 151.2, 141.2, 135.2, 133.9, 130.7, and 136.5, with a mean of 139.4. Estimated planetary A indices were 5, 9, 7, 66, 76, 10, and 15, with a mean of 26.9. Middle latitude A index was 5, 8, 6, 32, 39, 7, and 12, with a mean of 15.6.

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.

For this week’s ARRL Propagation Bulletin ARLP016:

This week’s sunspot numbers and solar flux were higher than the week before.

Average daily sunspot numbers were more than doubled, from 70.6 to 146.9, and average daily solar flux increased from 141 to 164.5. Both figures represent a substantial increase in solar activity.

Planetary A index averages went from 7.6 to 8.1, while middle latitude A index advanced from 6.4 to 7.3.

Predicted solar flux over the next few weeks is 145, 140, and 135 on April 20 – 22; 130 on April 23 – 24; 125 on April 25 – 26; 160 on April 27 – 29; 165 on April 30; 172 on May 1 – 3; 170 on May 4; 172 on May 5 – 7; 178 on May 8; 182 on May 9 – 12, then 175, 178, and 170 on May 13 – 15; 168 on May 16 – 17; 175 on May 18, and 172 on May 19 – 21.

Predicted planetary A index is 20, 16, 12, and 10 on April 20 – 23, then 8, 5, 15, and 18 on April 24 – 27; 15 on April 28 – 30, then 12 and 10 on May 1 – 2; 8 on May 3 – 4; 5 on May 5 – 6; 12 on May 7; 5 on May 8 – 10, then 8 on May 11 – 12; 5 on May 13 – 18, then 10, 8, 5, and 5 on May 19 – 22.

Dan Handa, W7WA, commented on the news item last week about the current solar cycle reaching a peak earlier than predicted, perhaps by the end of this year.

I told him I hope it will not peak early because I want to see several more years of increasing activity.

Dan sent a detailed graph of Solar Cycle 19, from 1954 to 1966, and wrote, “I have read more than once [that] a slow rise means a low sunspot max. The previous [Solar] Cycle 24 took 5 years to reach a relatively low maximum. A rapid increase can mean a high sunspot maximum. The granddaddy of our lifetime, [Solar] Cycle 19, peaked in three years!” I was unaware of this.

Sunspot numbers for April 13 – 19, 2023, were 154, 153, 151, 155, 162, 140, and 113, with a mean of 146.9. 10.7-centimeter flux was 159.5, 171.3, 175.8, 177.8, 166.6, 153.2, and 147, with a mean of 164.5. Estimated planetary A indices were 6, 7, 9, 4, 6, 13, and 12, with a mean of 8.1. Middle latitude A index was 5, 10, 8, 4, 6, 9, and 9, with a mean of 7.3.