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The K7RA Solar Update


Solar activity took a dramatic plunge over the recent reporting week (June 23 to 29) but geomagnetic activity stayed exactly the same. Field Day weekend saw rising geomagnetic numbers, with planetary A index at 8, 16 and 23, Friday through Sunday.

On Sunday the geomagnetic activity was a problem, although not severe, with many stations in Field Day reporting increased absorption.  The planetary K index peaked at 5 (a big number) at the end of the UTC Day on Saturday and continued into the early hours of Sunday, which was early Saturday evening here on the West Coast.

This happened because of a crack in Earth's magnetosphere, detailed here:

Compared to the previous seven days, average daily sunspot numbers declined from 124.6 to 49.1, while average daily solar flux dropped from 140.5 to 105.3.

Planetary and middle latitude A-index averages were both the same as the previous week, all numbers around 11.

The prediction from the USAF 557th Weather Wing is not very optimistic, with solar flux peaking at 140 on July 11 to 16.

The prediction shows 10.7 cm solar flux at 90 on July 1, 95 on July 2, 105 on July 3 to 5, then 110, 120, 130 and 135 on July 7 to 10, 140 on July 11 to 16, then 135, 130, 125 and 120 on July 17 to 20, and 115, 110, 105 and 100 on July 21 to 24, 95 on July 25 and 26, 100 on July 27 to 29, then 105, 110, 115, 120 and 125 on July 30 through August 3, then 130 on August 4 and 5, and back to 140 again on August 7 to 12.

Predicted planetary A-index is 5 on July 1 to 7, then 8, 8, 12 and 8 on July 8 to 11, 5 on July 12 and 13, 12 on July 14 to 16, 10 on July 17, 8 on July 18 to 21, then 12, 15, 15 and 10 on July 22 to 25, and 5 on July 26 through August 4, then 8, 12 and 8 on August 5 to 7.

F. K. Janda, OK1HH writes, "Solar activity has declined over the last seven days.  Geomagnetic activity was highest on June 26(G1-class geomagnetic storm broke out around midnight UT on June 25and 26) and was lower on June 28 and 29.  On June 26, a big, bright CME billowed away from the sun's southern hemisphere.  A slow-moving CME that left the sun could pass close to Earth on June 30.  The near miss, if it occurs, could disturb our planet's magnetic field.

A dark filament of magnetism erupted in the sun's northern hemisphere on June 28, but no CME was observed after the explosion. Shortwave propagation conditions were relatively worse on June 26 and 27.  After that, they began to improve, but only very slowly due to the declining solar activity."

A new space weather report and forecast from Dr. Tamitha Skov, WX6SWW, our Space Weather Woman.

Tomas Bayer of the Department of Geomagnetism, RWC Prague, at the Budkov Observatory wrote this geomagnetic activity summary:

"After the last active events on June 24 to 26, which without a storm event did not exceed the active level (local K-index = 4), we expect a geomagnetic activity decrease to quiet to unsettled level during the coming seven days.

More unsettled geomagnetic activity can be expected about July 3 and 4, and also at the end of the currently forecast period on July 7. Then we expect geomagnetic activity at a quiet to unsettled level." Here are pictures of the Budkov Observatory:

How big is our nearest star?

Cycle forecasts, wrong or right?

Storm watch, from the popular press:

Reader David Moore, a frequent contributor, sent this:

It hasn't been updated recently, but here is a blog devoted to propagation:

Send your tips, questions, or comments to

For more information concerning shortwave radio propagation, see and the ARRL Technical Information Service at For an explanation of numbers used in this bulletin, see

An archive of past propagation bulletins is at More good information and tutorials on propagation are at

Instructions for starting or ending email distribution of ARRL bulletins are at

Sunspot numbers for June 23 through 29, 2022 were 69, 60, 31, 33, 32, 71, and 48, with a mean of 49.1.  10.7 cm flux was 121.4, 115.4, 108.1, 102, 98.2, 96.1, and 96.2, with a mean of 105.3.  Estimated planetary A indices were 10, 8, 16, 23, 12, 8, and 6, with a mean of 11.9. Middle latitude A index was 12, 8, 14, 15, 15, 11, and 7, with a mean of 11.7.



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