Register Account

Login Help

ARRL Propagation Bulletin ARLP006 (2018)

ARLP006 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 6  ARLP006
From Tad Cook, K7RA
Seattle, WA  February 9, 2018
To all radio amateurs 

ARLP006 Propagation de K7RA

Compared to the previous seven days, solar activity increased in the
first week of February. There were two days with no sunspots,
February 1 and 3. On February 2 a new sunspot region emerged, but by
the next day it had disappeared. Another sunspot region appeared on
February 4, and the area it covered on February 4-7 was 80, 130, 160
and 200 millionths of the solar hemisphere.

We haven't seen as much coverage since October 7, 2017 when the
total sunspot area was 220 millionths of the solar hemisphere and
the sunspot number was 11, the minimum non-zero sunspot number.

A dozen days prior on September 25 the sunspot number was 36 and the
total sunspot area (as always, expressed in millionths of a solar
hemisphere) was 560.

You can see that already the sunspot numbers and solar flux have
dropped since last year:

As a reference, you can compare these numbers with the peak of the
current cycle in 2014:

Note the year contained in the above two URLs. You can edit that to
look at any year, back to 1994.

You can look here to see graphs of sunspot and solar flux activity,
and see what the daily numbers were for the previous peak and

So last week the average daily sunspot number increased from 3.7 (at
the end of January) to 10.3 and average solar flux from 69.1 to
72.5. Average planetary A index decreased modestly from 6.3 to 4.4,
while average mid-latitude A index (measured at one location, in
Virginia) decreased from 4.9 to 3.6.

The heightened activity should continue over the next week.
Predicted solar flux is 78 on February 9-10, 76 on February 11-12,
74 on February 13-14, 72 on February 15-16, 70 on February 17-22, 69
on February 23-28, 70 and 71 on March 1-2, 72 on March 3-14, 71 on
March 15, 70 on March 16-21, and 69 on March 22-25.

Predicted planetary A index is 8 on February 9, 5 on February 10-16,
then 8, 10, 5, 8, 10, and 8 on February 17-22, 5 on February 23
through March 13, then 8, 12, 8, 10, 5, 8, 10 and 8 on March 14-21
and 5 on March 22-25.

F.K. Janda, OK1HH sent this geomagnetic activity forecast for the
period February 9-March 8, 2018.

"Geomagnetic field will be:
Quiet on February 12-14, 20
Mostly quiet on February 17, 23, 25-27, March 1-3, 5-8
Quiet to unsettled on February 11, 15, 18-19, 21-22, 24, 28
Quiet to active on February 9-10, 16, March 4
Active to disturbed-not anticipated

"Amplifications of the solar wind from coronal holes are expected on
February 5-6, 9-12, 18-19, 27-28."

Al Kaiser, N1API of Meriden, Connecticut sent a report on Sunday,
February 4:

"During the 10-10 QSO Party on Sunday February 4 we had what was
probably a nice sporadic-E opening that started with NC about 1507
UTC, then nothing until TN on 1704 which quickly changed to solid
signals from OH, IL, IN, AND MI.  By about 1822 it was all over. 10
meters always has some surprises in store."

Jeff, N8II reported from West Virginia on February 8:

"This week, there is very little good news of improved openings on
17 (a bit better than a week ago) and 15 meters so far despite the
considerably higher SFI.

"But, all of the low bands including 160 seem better thanks to more
ionosphere. Tonight, February 9 UTC, I worked A45XR (Oman) first
call on 80M CW at 0053Z who was S8 and around the same time logged
Denmark and Slovenia with good signals. I also logged Z61DX Kosovo,
on 17M CW at 1540Z today February 8th for a new band country and
Z60A was S9 on 40 CW tonight, but too many calling to get through.
There were many S9+ Europeans on 20M this morning, much better
signals than a month ago."

A new space weather video from Dr. Tamitha Skov can be seen at:

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 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 February 1-7, 2018 were 0, 11, 0, 11, 13, 17,
and 20, with a mean of 10.3. 10.7 cm flux was 69, 68.8, 69.2, 73,
74, 76.9, and 76.6, with a mean of 72.5. Estimated planetary A
indices were 4, 4, 3, 3, 8, 5, and 4, with a mean of 4.4. Estimated
mid-latitude A indices were 2, 3, 2, 3, 8, 4, and 3, with a mean of


Instragram     Facebook     Twitter     YouTube     LinkedIn