Subj : The K7RA Solar Update
To   : QST
From : ARRL de WD1CKS
Date : Fri May 31 2024 07:28 pm

05/31/2024

SB PROP @ ARL $ARLP020
ARLP020 Propagation de K7RA �

ZCZC AP20
QST de W1AW��
Propagation Forecast Bulletin 20� ARLP020
From Tad Cook, K7RA Seattle, WA� May 31, 2024
To all radio amateurs� �

SB PROP ARL ARLP020
ARLP020 Propagation de K7RA �
Solar activity was quiet this week. Average daily sunspot number slipped from
155.1 to 124.6, and average solar flux from 198.9 to 164.8. �

Geomagnetic conditions were quiet, with average planetary A index going from
13.9 to 7.9, and middle latitude A index from 11.7 to 9.

Eight new sunspot groups emerged, one on May 23, two on May 25, four on May 26,
and one on May 28.

The outlook for the next month predicts solar flux at 175 on May 31 through
June 6, then 210, 200, 195, 190, 185 and 180 on June 7-12, 170 on June 13-14,
165 on June 15, 190 on June 16-17, 185 on June 18, then 190 on June 19-20, then
185, 195 and 200 on June 21-23, then 210, 210 and 215 on June 24-26, 225 on
June 27-29, 220 on June 30 through July 1, 210 on July 2-4, then 200, 195 and
190 on July 5-7.

Predicted planetary A index is 25 on May 31 and June 1, 5 on June 2-7, then 10,
12, 8, 12 and 10 on June 8-12, 5 on June 13-19 then 15 and 12 on June 20-21,
then 5, 12, 8 and 5 on June 22-25, and 5, 10, 12, 12 and 8 on June 26-30, then
5 on July 1-4, then 10, 12, 8, 12 and 10 on July 5-9.

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere
from OK1HH.

"Over the past seven days, two active regions have returned to the solar disk
where large solar flares with CMEs were observed during the last solar
revolution. These were regions AR3663 and AR3664, now designated AR3691 and
AR3697. The activity of the latter caused a major geomagnetic storm with
auroras on 10 May, the largest in decades. Until these large groups of spots
reach the center of the solar disk or near the central meridian (i.e.,
approximately June 6-7), solar activity will increase in a roughly 20-day
fluctuation and then decrease again.

"Even the last major solar flare on May 29 afternoon UTC was observed in AR3697
and was accompanied by a CME. Part of the particle cloud will probably hit
Earth sometime between late afternoon on June 1 and the morning of June 2. The
onset of the phenomenon should be accompanied by an improvement in shortwave
propagation conditions and a deterioration can be expected during its
continuation on June 2.

"In the following days, due to increasing solar activity and a calmer state of
the Earth's magnetosphere, shortwave propagation should improve again. However,
if another large solar flare occurs, the development could be much more
dramatic. Another reason for the current instability of shortwave conditions is
the rise in Summer sporadic-E layer activity in the northern hemisphere.

Spaceweather.com reports NOAA forecasters say a G2 class geomagnetic storm is
possible on May 31 when a CME grazes earth. But a NASA forecast suggests a near
miss. This is from a CME at 1433 UTC on May 29 from sunspot group AR3664.

More on sunspot group AR3664: �

https://bit.ly/4bAeJKA[1] �

https://bit.ly/3wY48tT[2] �

https://tinyurl.com/2p9c98tm[3] �

https://tinyurl.com/mskr6ptb[4] �

https://tinyurl.com/ypnjcc6d[5] �

https://tinyurl.com/2pvuk5db[6]

The latest video from Dr. Tamitha Skov, WX6SWW:
https://youtu.be/O2Y9QGLMvsc[7] �

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

For more information concerning shortwave radio propagation, see
http://www.arrl.org/propagation and the ARRL Technical Information Service web
page at, http://arrl.org/propagation-of-rf-signals[8]. For an explanation of
numbers used in this bulletin, see
http://arrl.org/the-sun-the-earth-the-ionosphere.

An archive of past propagation bulletins is at
http://arrl.org/w1aw-bulletins-archive-propagation[9].

More good information and tutorials on propagation are at http://k9la.us/[10] .

Also, check this QST article about Solar Indices: � https://bit.ly/3Rc8Njt[11]

Instructions for starting or ending email distribution of ARRL bulletins are at
http://arrl.org/bulletins[12].

Sunspot numbers for May 23 through 29 2024 were 130, 100, 106, 148, 116, 141,
and 131, with a mean of 124.6. 10.7 cm flux was 176.2, 162.8, 152.4, 155.6,
170, 166.4, and 170.5, with a mean of 164.8. Estimated planetary A indices were
10, 9, 6, 10, 8, 6, and 6, with a mean of 7.9. Middle latitude A index was 10,
11, 6, 10, 9, 7, and 10, with a mean of 8.

NNNN
/EX� ��


[1] https://bit.ly/4bAeJKA
[2] https://bit.ly/3wY48tT
[3] https://tinyurl.com/2p9c98tm
[4] https://tinyurl.com/mskr6ptb
[5] https://tinyurl.com/ypnjcc6d
[6] https://tinyurl.com/2pvuk5db
[7] https://youtu.be/O2Y9QGLMvsc
[8] http://arrl.org/propagation-of-rf-signals
[9] http://arrl.org/w1aw-bulletins-archive-propagation
[10] http://k9la.us/
[11] https://bit.ly/3Rc8Njt
[12] http://arrl.org/bulletins

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