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ARRL Propagation Bulletin ARLP048 (2020)

ARLP048 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 48  ARLP048
From Tad Cook, K7RA
Seattle, WA  December 1, 2020
To all radio amateurs 

ARLP048 Propagation de K7RA

Over the past week our Sun has been quite active, with rising
sunspot numbers and solar flux showing strong evidence that Solar
Cycle 25 is progressing.

Average daily sunspot number rose from 12 last week to 27.9 in the
current week, while solar flux rose to a high of 103.7, bringing
average daily solar flux up from 79.8 to 90.1.

Average daily planetary A index rose from 3.1 to 9.9, and average
daily middle latitude A index went from 2.1 to 7.7.

Predicted solar flux is 106, 108 and 105 on November 27-29, 102 on
November 30 through December 4, then 92, 88 and 85 on December 5-7,
then 82, 80 and 78 on December 8-10, 75 on December 11-17, then 77,
80, 90 and 92 on December 18-21, 94 on December 22-25, 92 on
December 26 through January 1, 2021, then 88, 85, 82, 80 and 78 on
January 2-6, and 75 on January 7-10.

The Planetary A Index forecast shows values of 8 on November 27, 5
on November 28 through December 17, then 12, 24 and 18 on December
18-20, 10, 12 and 10 on December 21-23, 5 on December 24-29, 8 on
December 30-31, and 5 on January 1-10, 2021.

Solar flux is measured thrice daily in Penticton, British Columbia,
and values have risen steadily in the past few days. Starting at
2200 UTC on November 24, they were 99.6, 102.8, 103.7, 104, 105.7,
105.8 and 110.2.

See them here:

The official daily flux value is taken at noon, local time in
Penticton, which is 2000 UTC.

VA7JW article about the observatory:

Geomagnetic activity forecast for the period November 27 until
December 22, 2020 from OK1HH:

"Geomagnetic field will be,
quiet on: December 7, 12-14, (15-16)
quiet to unsettled on: November 29-30, December 1-2, 6, 8, 11
quiet to active on: November 27-28, December 3-5, 9-10, 17, 22
unsettled to active: December 18, 21
active to disturbed: December 19-20
"Solar wind will intensify on: November (30,) December (2,) 3-5,
(9,) 17-19.

"Parenthesis means lower probability of activity enhancement. The
predictability of changes remains lower because there are still few
unambiguous indications. In addition, the situation is relatively
rapidly changing. Which, by the way, is an indicator of further
growth in activity."

Jon Jones, N0JK reported on November 25:

"Sporadic-E is picking up on 6 Meters as Thanksgiving approached.

"Had K0GU (DN70) into northeast KS via Es on 50.313 MHz ~ 2344z with
'-12 dB' signals on FT8 November 24.

"Noted K0GU made a number of contacts into the St. Louis, MO area
and W9. Also saw AC4TO (EM70) in Florida working Brazil ~ 0050z
November 25. May have been a sporadic-E link to TEP or possibly
direct TEP.

"A typical spot: PY1MHZ  20/11/25 0057Z  50313.0 Into EM70 AC4TO"

KA3JAW reported November 25:

"Sporadic-E, both double and triple-hop rolled-up on 10 meters for
six hours starting around 1253 till 1921 UTC.

"Background noise level was 4 dBm on the signal strength meter.

"The following countries, states heard: Trinidad, West Indies, AZ,
Canada, CO, KS, NM, OK, TX, WA

"Texas was the most heard state.

"What was different with this event was the lack of southeastern
AA8WH reported:

"This is Bill Herzberg, AA8WH, of Dearborn Heights, Michigan. Just
wanted to let you and everybody else know, 10 METERS IS ALIVE AND

"Starting after noon on November 25, I decided to check out the 6m
and 10m FT8 frequencies. Wasn't much happening on 6m, only heard a
few calls, so I moved down to 10m. Boy what a difference. 10m FT8
signals were coming in from all over the place.

"I decided to go down to the sideband portion and see what was going
on. Heard lots of ssb stations around 28.4. Heard some more above

"Went down to 28.3, and heard several really strong stations.

"Went down to the beacon subband, heard beacon stations, lots of
'em, some doubling up on frequencies.

"So I went down to 12m. Heard several SSB stations, FT8 was hopping.
15m was wide open, as was 17m. 20m was also going strong.

"I think that it was a combination of better conditions and a lot of
folks home for the holidays.

"Nice to hear the bands open. It's a taste of what's coming, when it
will be possible to work the world with a few watts. Those times are
coming, and it won't be soon enough for me."
Thanks to Paul NO0T for this recording of Dr. Scott McIntosh (see for his CV) and his presentation to the
"Front Range 6 Meter Group" concerning Solar Cycle 25:

Don't miss this! Some of what he reports is quite startling, and

Coming up in two weeks is the ARRL 10 Meter contest, which will
especially benefit from higher solar activity. See for details.
See this article on helioseismology and sunspot prediction:
Dr. Tamitha Skov, WX6SWW, is very excited about the new solar

If you would like to make a comment or have a tip for our readers,
email the author at,
For more information concerning 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 19 through 25, 2020 were 11, 11, 23,
35, 38, 37, and 40, with a mean of 27.9. 10.7 cm flux was 76.7,
81.7, 85, 87.7, 95.5, 100.4, and 103.7, with a mean of 90.1.
Estimated planetary A indices were 3, 8, 12, 27, 8, 4, and 7, with a
mean of 9.9. Middle latitude A index was 2, 9, 9, 19, 7, 4, and 4,
with a mean of 7.7.


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