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ARRL Propagation Bulletin ARLP046 (2021)

ARLP046 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 46  ARLP046
From Tad Cook, K7RA
Seattle, WA  November 12, 2021
To all radio amateurs 

ARLP046 Propagation de K7RA

Sunspot activity and solar flux dropped this reporting week
(November 4-10), with the average daily sunspot number retreating
from 67.6 to 36.4, and solar flux from 102 to 89.1. Geomagnetic
indicators rose, average daily planetary A index from 12 to 18, and
middle latitude values from 9 to 11.7.

When the planetary and middle latitude A index were 69 and 42 on
November 4, Alaska's College A index was a whopping 131. College K
index peaked at 9 on that day. K index is logarithmic, so each point
in the scale represents a big difference in activity. The A index is
linear, and based upon the K index.

The K index is reported every three hours, and the College K index
on November 4 was 5, 5, 8, 9, 8, 5, 3 and 2. This was all caused by
what called a "Cannibal CME," because it was a CME
overtaken by a second larger and faster moving coronal mass

At 1701 UTC on November 9 a CME eruption just over the Sun's western
horizon emitted enough energy to cause a shortwave radio blackout,
which is pictured here:

Predicted solar flux is 86 on November 12, 85 on November 13-16, 84
on November 17, 83 on November 18-19, 90 on November 20, 95 on
November 21-27, 90 on November 28-29, 85 on November 30 through
December 2, 82 on December 3-4, 85 on December 5, 82 again on
December 6-9, 80 on December 10-11, 85 on December 12, and 87 on
December 13-15. Flux values may peak at around 95 on December 18-24.

Predicted planetary A index is 5 on November 12-15, 8 on November
16-17, 5 on November 18-27, then 10, 10 and 8 on November 28-30, 5
on December 1-4, 8 on December 5, 5 on December 6-9, then 7, 7, 10
and 8 on December 10-13, and 5 on December 14-24.

F. K. Janda, OK1HH presents his geomagnetic activity forecast for
the period November 12 to December 1, 2021.

"Geomagnetic field will be:
quiet on: 18-19, 23, 25, 
quiet to unsettled on: November 12-13, 17, 20, 22, 24, 
quiet to active on: November 21, 26-27, 
unsettled to active on: November 14, 16, 28,
Active to disturbed: November (15, 29,) 30, December 1, 

"Solar wind will intensify on November 16-17, (29-30), December
(1-2,) 3-4.

"Parenthesis means lower probability of activity enhancement."

Don't know why I had not noticed this before:

Unfortunately, only one of the two spacecraft remains, but it is
still a very useful tool:

N0JK wrote from Kansas:

"Good conditions on 17 meters Sunday afternoon November 7. I found
the HD8R Galapagos Island DXpedition on 18.147 MHz SSB loud with few
callers. Was able to work them easily with 5 watts and mobile whip
at 2022 UTC. Sometimes a DXpedition is easier to work on the WARC

Early on November 12, reported all is quiet for

"Space weather near Earth is calm, but the Sun is not quiet. This
week, SOHO coronagraphs have observed multiple CMEs billowing over
the western edge of the Sun. The source is a farside sunspot group,
probably the same one that produced a strong M2-class solar flare on
November 9th. Earth is not in the line of fire, for now."

Another great video report from Dr. Tamitha Skov, WX6SWW, the Space
Weather Woman:

If you would like to make a comment or have a tip for our readers,
please email the author at, .

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

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

Sunspot numbers for November 4 through 10, 2021 were 28, 40, 41, 28,
41, 40, and 37, with a mean of 36.4. 10.7 cm flux was 93.8, 92.8,
82.1, 87.5, 88.3, 92, and 87.5, with a mean of 89.1. Estimated
planetary A indices were 69, 13, 18, 6, 5, 7, and 8, with a mean of
18. Middle latitude A index was 42, 9, 13, 4, 3, 6, and 5, with a
mean of 11.7.


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