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ARRL Propagation Bulletin ARLP038 (2016)

ARLP038 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 38  ARLP038
From Tad Cook, K7RA
Seattle, WA  September 16, 2016
To all radio amateurs 

ARLP038 Propagation de K7RA

The Autumnal Equinox is next Thursday, September 22, 2016 at 1421
UTC. This indicates a transition from Summer to Fall, and the
associated improved HF propagation.

Over our reporting week (September 8-14) average daily sunspot
numbers rose from 46.4 to 50.1, and average daily solar flux
declined from 95.1 to 88.9.

This is the opposite of what occurred the previous week, when
sunspot numbers declined and solar flux rose. Normally we expect
solar flux and sunspot numbers to track together.

Geomagnetic indicators were very quiet, with average daily planetary
A index declining from 26.6 to 6.7, and mid-latitude A index from
18.1 to 6.1.

The latest NOAA/USAF forecast has solar flux at 85 on September
16-17, 80 on September 18-19, 75 on September 20, 80 on September
21-22, 75 on September 23-24, then 72, 78 and 80 on September 25-27,
78 on September 28-30, 82 on October 1-2, 80 on October 3-7, then
82, 86 and 82 on October 8-10, 80 on October 11-12, 75 on October
13-14, 70 on October 15-16, and 75 on October 17-21, then 72, 78 and
80 on October 22-24.

Predicted planetary A index is 8 on September 16-17, then 5, 18, 20,
12 and 8 on September 18-22, 5 on September 23-25, then 15, 8, 38,
40 and 42 on September 26-30, then 30, 18, 15, 12 and 10 on October
1-5, then 5 on October 6-8, 15 on October 9, 8 on October 10-11, 5
on October 12-13, 12 on October 14-16, then 15 and 10 on October
17-18 and 5 on October 18-22.

"Geomagnetic activity forecast from OK1HH for the period September
16 to October 12, 2016

"Geomagnetic field will be:
Quiet on September 18, 23-24, October 4-7, 11-12
Mostly quiet on September 16-17, 22, 25, October 3, 8
Quiet to unsettled on September 21, 26-27, October 2, 9-10
Quiet to active on September 19-20, October 1
Active to disturbed on September 28-30

"Increases in solar wind from coronal holes are expected on
September (18,) 22, 26-28, October 1.

"Remark: - Parenthesis means lower probability of activity

"F.K. Janda, OK1HH Czech Propagation Interest Group"

A note here from K7RA about minor changes to this weekly Czech
geomagnetic bulletin, which I perform in an effort to put the
translation in more standard English.

Where it says "increases in solar wind" the actual original text is
"amplifications of solar wind."

Also where it says "Czech Propagation Interest Group," the original
text says "Czech Propagation Interested Group."

Jeff Hartley, N8II in Shepherdstown, West Virginia wrote on
September 9:

"I have not been very active this week, but can report generally
poor conditions except fairly good to mid and southern Europe on 20
meters excluding Russia. The nearly constant disturbances one after
the other had their effect during the weekdays and over the weekend
when I took part in the Colorado and Tennessee QSO parties. 20
meters was poor to Colorado until about 1900Z Saturday, but there
were some booming signals on 20 in the evening and I made 2 QSOs
with W0ETT/M (mobile) on 40 over an all daylight path. Sunday was
good to Tennessee on 40 meters and below, but 20 meters was very
poor with only weak backscatter.

"I worked TY2AC in Benin, Africa on 15 meters CW around 2030Z
Thursday when he was S2-3; today he was S9 around 1530Z and some
southern Europeans were also coming through with finally a K of 1!

"All week the K index seems to have varied between 3 and 5 with rare

Ken Roth, KX6X in Sierra Vista, Arizona wrote:

"There have been a number of guys and gals warning that even when a
band appears to be 'dead.' that it may not be dead; it's just that
no one is transmitting. That was proved last evening (Sept. 9) when
I turned on my rig around 0415 UTC and tuned through 20 meters and
there was not a single signal to be heard. No SSB, no digital, no
CW. Nothing. Zero. Nada.

"I then called CQ around 14.055 with no responses. Then at 0420 UTC,
I tuned down to around 14.020 and there was JA7NUT calling 'CQ' with
a solid 569.

"I called him and he gave me a 579. And guess what? When I told him
that he was the only signal on the band that I could hear, he said
that this was exactly the case for him in Japan as well.

"Think about it, in both Japan and the US, neither of us could hear
any signals, and yet we ended up discovering that the propagation
path between us was in very good shape! Proof once again, that the
bands are not dead, it's just that we're not transmitting!"

This reminds me of something I read 50 years ago (many times in ARRL
publications), when I was a young teenaged ham. There was an
emphasis on instructing new hams to listen, above all else. Maybe
this was an effort to encourage new radio operators to listen first
before transmitting, but my impression at the time was that they
were encouraging us to listen much more often than calling CQ. But
if everyone is listening instead of calling, how likely would it be
that they will discover paths over radio?

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 the
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 September 8 through 14 were 49, 65, 66, 63, 57,
27, and 24, with a mean of 50.1. 10.7 cm flux was 94.5, 91, 93,
86.4, 86.5, 86, and 85.2, with a mean of 88.9. Estimated planetary A
indices were 14, 5, 5, 4, 6, 5, and 8, with a mean of 6.7. Estimated
mid-latitude A indices were 12, 6, 4, 3, 6, 4, and 8, with a mean of


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