Secure Site Login

ARRL Propagation Bulletin ARLP004 (2020)

ARLP004 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 4  ARLP004
From Tad Cook, K7RA
Seattle, WA  January 24, 2020
To all radio amateurs 

ARLP004 Propagation de K7RA

No sunspots appeared over this reporting week (January 16-22) and on
January 22 reported currently the consecutive
period of spotless days is 11. But all recent sunspots have had
Solar Cycle 25 polarity.

Average daily solar flux reported in last week's bulletin was 72.5,
and this week it was 71.2.

Average daily planetary A index went from 5.6 to 4.1, and the middle
latitude A index changed from 3.7 to 3.

Predicted solar flux is 71 on January 24-31, 72 on February 1-5, 71
on February 6-20, 72 on February 21 to March 3, 71 on March 4, and
70 on March 5-8.

Predicted planetary A index is 5 on January 24-31, 10 on February
1-5, 5 on February 6-27, 10 on February 28 to March 3, and 5 on
March 4-8.

Geomagnetic activity forecast for the period January 24-February 19,
2020 from F.K. Janda, OK1HH.

"Geomagnetic field will be
quiet on: January 29-30, February 6-9, 13-16
quiet to unsettled on: January 24-28, February 1, 4-5, 10-11, 18-19
quiet to active on: (January 31, February 2-3, 12, 17)
unsettled to active on: no days
active to disturbed: no days

"Solar wind will intensify on: January 24, February 2 (-3,) 6-7,
12-13, 18-19

"Parenthesis means lower probability of activity enhancement.  The
predictability of changes is lower again"

David Moore sent this article, "Scientists measure the evolving
energy of a solar flare's explosive first minutes." .

New from Dr. Tamitha Skov, WX6SWW: .

On January 21, G4KSG told me that two days earlier using a dipole at
30 feet he heard both sides of a EA3/JA7 QSO at 0900 UTC on 20
meters, but he did not specify the mode.

From Jeff, N8II:

"WX is very warm here after 4 inches of wet snow and 3 cold days
this week, currently about 52F at 9PM, 66 tomorrow!

"I took down a 40M quad loop today which performed poorly compared
to my 80M dipole fed with ladder line. It took a while to remove all
of the wire wrapped with stiff heavy wire at the insulators to
prevent slippage and untie tight knots. I will put up a 40M dipole
with higher average height.

"In the past month my band slot totals have increased considerably,
about 1950 slots since Jan. 2017 now as I recall counting the same
country on CW and SSB on same band as 2 slots. Very few DXpeditions
were active, but activity and low band condx were good over
Christmas season.  A UK group at ZC4UW in the British bases on
Cyprus was active with over 25K QSOs, but good for only 1 slot as
ZC4A was QRV another year.

"73, Jeff N8II."

When there are no sunspots, 160 meters seems to improve, probably
because of lower associated geomagnetic activity. In fact,
geomagnetic activity is recently nearly non-existent. This weekend
is the CQ World Wide 160 Meter CW contest. See details at,

Note the low geo-activity toward the end of 2019:

Compared to 2015:

Note October 29-30, 2003!

Check this bulletin from back then:

Be sure to check out the SSN/flux values for that week!

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

Monthly propagation charts between four USA regions and twelve
overseas locations are at

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

Sunspot numbers for January 16 through 22, 2020 were 0, 0, 0, 0, 0,
0, and 0, with a mean of 0. 10.7 cm flux was 71.8, 70.1, 71.3, 71.8,
71.2, 70.5, and 71.9, with a mean of 71.2. Estimated planetary A
indices were 5, 3, 4, 3, 2, 6, and 6, with a mean of 4.1. Middle
latitude A index was 4, 2, 3, 2, 2, 4, and 4, with a mean of 3.