QST de W1AW  
Propagation Forecast Bulletin 49  ARLP049
>From Tad Cook, K7RA
Seattle, WA  December 8, 2023
To all radio amateurs 

SB PROP ARL ARLP049
ARLP049 Propagation de K7RA

Six new sunspot groups emerged over this reporting week (November 30
to December 6).

Last week, using the previous week's Propagation Forecast bulletin
as a template, the averages were not updated, although all the
correct data was there.

So instead of average daily sunspot number of 83.3, it was actually
165.9, which this week dropped to 121.1.

Instead of average daily solar flux of 146, it was actually 181.5,
which this week declined to 146.5.

Instead of average daily planetary A index of 10.1, it was actually
11.6, which this week rose to 17.1. Instead of average middle
latitude A index of 7.3 it was 9, rising this week to 11.4.

Predicted solar flux is 135, 130, 130 and 135 on December 8-11, 137
on December 12-15, 140 and 150 on December 16-17, 160 on December
18-26, then 155, 150, 145, and 140 on December 27-30, then 136, 134
and 130 on December 31 through January 2, 2024, and 132 on January
3-5, then 130 and 135 on January 6-7, then 140 on January 8-12.

Predicted planetary A index is 5 on December 8-9, 8 on December
10-11, 5 on December 12-17, then 15, 25, 8, 5, 20 and 10 on December
18-23, 5 on December 24-30, then 25, 10 and 8 on December 31 through
January 2, 2024, and 5 on January 3-6, then 10 and 8 on January 7-8,
and 5 on January 9-13.

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
Ionosphere, December 8-14, 2023 from OK1HH:

'After passing through a twenty-seven day low in mid-November, solar
activity began to increase. Slowly at first, then steeply in recent
days. What was common to the whole period was that the predictions
of further developments were not fulfilled. Shortwave conditions
were, with a few exceptions, worse than expected.

'In the second half of last week, the Earth's magnetic field was
calm despite the eruption of a magnetic filament on the Sun on
November 16, which threw a CME almost directly toward the Earth. We
expected the CME to arrive on November 19. On the contrary, quiet
days followed on November 19-20.

'Then, despite seven new sunspot groups and calm in the Earth's
magnetosphere, propagation did not improve until November 20.

'Improvement occurred on 21 November, when the onset of the
geomagnetic disturbance was accompanied by two positive phases of
development with increases in MUF and an overall improvement in
conditions (at intervals of 1000-1300 UTC and 1600-1900 UTC).

'The following evolution could be expected - there was a
deterioration of conditions in the negative phase of the disturbance
development on 22 November. However, the deterioration was
short-lived, after which, thanks to the increasing solar activity,
an improvement occurred already on 23 November.

'Although solar activity continues to increase, there is a coronal
hole near the five active regions in the northeast quadrant of the
solar disk. This configuration will cause further increases in solar
wind speed and therefore more frequent alternation of better and
worse days.'

>From 'Universe Today' a story about a big, big solar storm in 1872:

https://bit.ly/3RgUWqL

A story about a big coronal hole:

https://bit.ly/487quGd

>From 'Science Alert' another article about a big hole on the Sun:

https://bit.ly/41adYDC

>From 'EarthSky' a new region on the Sun:

https://bit.ly/3RxtCWG

Don't forget, the ARRL 10 meter contest is THIS weekend!

https://www.arrl.org/10-meter

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.

An archive of past propagation bulletins is at
arrl.org/w1aw-bulletins-archive-propagation . More good
information and tutorials on propagation are at k9la.us/ .

Also, check this article from September, 2002 QST:

https://bit.ly/3Rc8Njt

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

Sunspot numbers for November 30 through December 6, 2023 were 138,
140, 92, 107, 113, 133, and 125, with a mean of 121.1. 10.7 cm flux
was 166.5, 162, 148.2, 139.2, 137.8, 141.6, and 129.9, with a mean
of 146.5. Estimated planetary A indices were 5, 56, 14, 11, 9, 15,
and 10, with a mean of 14.1. Middle latitude A index was 4, 30, 11,
10, 9, 9, and 7, with a mean of 7.3.