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The K7RA Solar Update



"A weak halo CME may impact Earth either on late UTC day 15-Jun or
else early UTC day 16-Jun.


Solar activity was lower over the past reporting week, June 6-12.

Ten new sunspot groups emerged, two on June 6, one on June 7, two on
June 9, and five on June 12.

Average daily sunspot number dropped from 44 points from 183.4 to
139.4, and average daily solar flux from 184.8 to 179.2.

Average daily planetary A index went from 8 to 11.6, and middle
latitude numbers from 9.4 to 11.1.

The most active day geomagnetically was June 7, when the planetary A
index was 28. Alaska's College A index was 38. This was an
unexpected G2 geomagnetic storm that commenced at 1130 UTC. reports a polar cap absorption event on June 12-13.
Protons from the Sun are raining down on Earth, and it is causing
shortwave blackouts. You can monitor it here:

Predicted solar flux shows a peak at 205 on June 26-29 and again on
July 23-26.

The forecast shows flux at 170 on June 14, 175 on June 15-17, then
180 on June 18-20, then 185, 190 and 195 on June 21-23, 200 on June
24-25, 205 on June 26-29, then 200, 190, 180, 175, 170, 165, 160 and
175 on June 30 through July 7, then 170 on July 8-9, 165 on July
10-11, 155 on July 12-13, then 165 and 175 on July 14-15, 185 on
July 16-18, then 190, 195 and 200 on July 19-21.

Predicted planetary A index is 5, 12 and 15 on June 14-16, then 8 on
June 17-18, then 5 on June 19-21, then 8 on Jun 22-23, then 5 on
June 24-29, 8 on June 30 and July 1, and 5 on July 2-6, then 8 on
July 7, 5 on July 8-15, then 8, 8, 5, 8 and 8 on July on July 16-20.

"Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
Ionosphere - June 13, 2024, from OK1HH:

"Despite the fact that the large sunspot group responsible for the
geomagnetic disturbances and the beautiful auroras of May 10-11 is
now on the far side of the Sun, its flares are showering the Earth's
surroundings with a rain of protons. On the whole, however, there is
no doubt that after its reappearance at the eastern edge of the
solar disk, solar activity will again increase significantly, with
solar flux values exceeding 200 in late June and early July.

"For now, we will be content with the consequences of a slight
decrease in overall solar activity, although moderate solar flares
are no exception. Upswells in geomagnetic activity occur only
occasionally and most days are quiet to unsettled. Summer prevails
in the Earth's northern hemisphere, and sporadic-E layer events
contribute even more than solar events to the erratic shortwave
propagation conditions here.

"With the exception of the two largest active regions, however,
there is little going on at present on the far side of the Sun, and
so July already seems to be considerably quieter than May and June

Radiation risks for Mars astronauts:

Viewing sunspots from Mars:

May solar images from various online sources:

Next weekend is ARRL Field Day, June 22-23. Solar flux and sunspot
numbers should be rising at that time, and predicted planetary A
index is a moderate 8.

There will be an updated forecast in next week's bulletin.

Send your tips, reports, observations, questions and comments to When reporting observations, don't forget to tell us
which mode you were operating.

For more information concerning shortwave radio propagation, see and the ARRL Technical Information
Service web page 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 .

Also, check this QST article about Solar Indices:

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

Sunspot numbers for June 6 through 12 2024 were 149, 150, 143, 148,
146, 95, and 145, with a mean of 139.4. 10.7 cm flux was 190.9,
184.4, 190.4, 180.9, 177.8, 164.9, and 164.9, with a mean of 179.2.
Estimated planetary A indices were 6, 28, 14, 5, 11, 12, and 5, with
a mean of 11.6. Middle latitude A index was 7, 20, 15, 6, 11, 13,
and 6, with a mean of 11.1.



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