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ARRL Propagation Bulletin ARLP039 (2016)

ARLP039 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 39  ARLP039
From Tad Cook, K7RA
Seattle, WA  September 23, 2016
To all radio amateurs 

ARLP039 Propagation de K7RA

Sunspot numbers and solar flux were down over our reporting week,
September 15-21.

Average daily sunspot number was 29.9, down from 50.1 during the
previous seven days. Average daily solar flux went down from 88.9 to

Geomagnetic indices were up a bit, with average daily planetary A
index rising from 6.7 to 8.9, and average daily mid-latitude A index
from 6.1 to 7.6. The predicted average planetary A index for the
next seven days is expected to rise to 13.1, and average solar flux
to 86.4, according to the latest 45-day outlook.

Predicted solar flux is 85 on September 23-24, 90 on September
25-26, 85 on September 27-28, 90 on September 29, 95 on September 30
through October 2, 90 on October 3-6, 85 on October 7-13, 80 on
October 14-15, 85 on October 16-20, 88, 90 and 95 on October 21-23,
100 on October 24-27, and 95 on October 28-29.

Predicted planetary A index is 5 on September 23-24, then 8, 18 and
12 on October 25-27, 35 on September 28-29, 32 on September 30, then
30 and 18 on October 1-2, 15 on October 3-5, then 5 on October 6-15,
then 18, 20, 12 and 8 on October 16-19, then 5 on October 20-22,
then 15 and 10 on October 23-24, and 35 on October 25-27.

Thursday, September 22 was the Autumnal Equinox, and the first day
of the Fall season. Around and after the equinox we should observe
better propagation than we've seen in the past couple of months, and reports that this is also the start of the aurora
season. Here is an article about aurora in autumn:

Here is a weekly update from OK1MGW.

"Geomagnetic activity forecast for the period September 23-October
19, 2016

"Geomagnetic field will be:
Quiet on September 23-24 October 6-8, 13-14
Mostly quiet on October 5, 9-10, 12, 15-16, 19
Quiet to unsettled on September 25, 27, October 3-5, 11
Quiet to active on September 26, 28-30, October 1-2, 17-18
Active to disturbed on September (29-30)

"Increases of the solar wind from coronal holes are expected on
September 25-26, 28-30, October 1-2, 16-18

"Remarks: - Parenthesis means lower probability of activity

"Petr Kolman, OK1MGW Czech Propagation Interest Group."

Jon Jones, N0JK of Lawrence, Kansas wrote, "The 2 meter Sprint
contest took place September 19/20 Monday evening. A coronal hole
solar stream reached the earth and a moderate geomagnetic storm took
place with the K index reaching 5. The storm occurred during the 2
meter sprint and many aurora contacts were reported by stations
along the northern tier states such as KA0RYT in EN35. The aurora
briefly reached Kansas. Around 0220z on September 20 I was working
KB0ZOM EN00 on 144.200 via tropo and his CW tone changed to aurora."
[I think this means it got all buzzy and distorted. - K7RA]

Scott Bidstrup, TI3/W7RI wrote:

"Don't know if you've seen this, but it could be of some interest to
your readers. The Kp index bar chart that we've all known and loved
since we were all novices is being replaced by a map that shows the
geomagnetic activity in various regions of the world, reflecting the
fact that geomagnetic activity is highly variable by latitude and
region. It's not up yet on the SWPC web site, but apparently it's
coming. The article includes a preview sample:


"The recent solar activity hasn't seemed to have improved our
propagation much down here in the single digit latitudes. 6 meters
has been so dead that everyone is asking why they have bothered with
6 meter stations. This should be a busy time of the year for evening
TEP into South America from here in the Central American isthmus,
but we're not seeing much of anything at all this season.  To be
sure we don't miss any openings no matter how weak, a couple of my
friends and I have taken to using JT65, but other than a couple of
short and weak Es openings into the Caribbean and Florida, there
hasn't been anything to speak of - very little TEP into South
America. We've managed a few, weak Es openings into the States -
I've worked a couple of stations in Arizona and New Mexico on JT65,
and of course the usual Florida, but not much else.  We had one good
opening recently into Cuba and Hispaniola, followed later by Puerto
Rico, but a hoped-for contact into HH never did materialize - two
stations were on, but I never heard either one. Conditions have been
so poor for so long that the joke going around here is that 'ten
meters is the new six.'

"The HF bands have been rather lackluster too. Other than some weak,
very sporadic aTEP openings into South America on 10m, there have
been almost no openings on 10m, and 12m hasn't been much better,
though Phil, TI5/N5BEK tells me he worked a ZS6 on 10m JT65
recently. I've had a few contacts into Europe on 15, and some
activity into the States, but even 15 meter openings have been
getting unreliable for us (and that's surprising - even at the
bottom of the last solar cycle, we usually had daily openings on 15m

"Even 20m seems to be affected by all this strange behavior. A daily
sked with Jerry, KA7G in northwestern Montana, has been interesting
to watch - usually, his signal is barely audible at 7AM local time
here, but will build slowly to an S9 by 7:30 or 8AM and then slowly
fade again and be all but inaudible by 9AM and through the rest of
the day, though on an increasing number of days it never gets
particularly strong.

"80m and 40m have been interesting, too, in that the refugees from
the higher bands seem to be moving onto 40m and 20m and those bands
are noticeably more crowded down here than they have been in the
last year or two. 40m has been especially impacted, and the crowding
here has been bad enough at times to force some of us into the
broadcast portion looking for space where we can find it.

"The odd delayed opening of the lower bands to short skip on 80m and
40m mentioned the last time I wrote, is continuing. Most of the
time, the 80m band will open for short skip right at sunrise, and
40m about a half hour later. Usually, the opening of the band in the
morning is remarkably abrupt - short skip will go from near zero to
very strong signals over the course of only three or four minutes,
rarely more than five. The time at which this has been occurring
seems to have been quite stable lately - the opening of 80m for
local paths is nearly always right around local sunrise. On days
when there is a lot of geomagnetic activity, this transition can
happen a few minutes earlier or later, with no real pattern."

Thanks, Scott!

Jan Beaver, KC0V of La Porte, Colorado wrote:

"Just a few notes on the much-maligned Cycle 24. Although it clearly
was not the equal of its two predecessors in terms of sheer
propagation, Cycle 24 has been very good to me. During Cycle 24 I
achieved the following milestones from Colorado:

"Five-band WAS (all CW) Five-Band DXCC (all CW) DXCC on 30, 17, and
12 meters (all CW) pushed my DXCC totals to 271 entities confirmed
on LoTW 2015 ARRL DX CW Rocky Mountain Division Winner (SOLP)

"Cycle 24 offered consistently good conditions on both the high and
low HF bands. I did improve my radios and antennas during the run of
Cycle 24, although my total station complement is still quite modest
by any standard. There were any number of days during Cycle 24 when
I made at least one DX contact on every band from 10 through 160
meters (except 60 meters which I do not work). Many contests offered
serious action across that same range of radio spectrum, all in a
weekend. So as much as I would like to experience a return of the
glories of Cycle 22 or whatever, I really have no complaints about
Cycle 24."

Now for a little comic relief, not so much lately but often in the
past I would receive emails from people trying to correlate solar
activity with all kinds of things, which always seemed to me to be a
fool's errand.

Here is a recent article promoting this theory, for betting on

It is interesting to click on that chart of past solar cycles
referenced against economic indicators. When you see it in larger
format such as , it looks to me like there is
no correlation between low solar activity and economic recessions,
or at least the theory seems to have little predictive value.

Speaking of little predictive value, back in Propagation Forecast
Bulletin ARLP037 in discussing grand maximums in solar activity, I
noted that over the past 11,000 years there were 19 grand maximums
such as Cycle 19 in the late 1950s. So in an attempt to see how rare
these are, I did some simple arithmetic and realized that it is rare
enough that there is on average about 579 years between these grand
maximums. But I should point out that they don't occur at regular
intervals, so projecting forward to the year 2537 AD is meaningless.

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 15 through 21 were 12, 13, 14, 47, 56,
32, and 35, with a mean of 29.9. 10.7 cm flux was 84.4, 83.7, 80.3,
83, 82.6, 84.5, and 85.5, with a mean of 83.4. Estimated planetary A
indices were 7, 3, 4, 9, 10, 19, and 10, with a mean of 8.9.
Estimated mid-latitude A indices were 6, 3, 4, 8, 8, 15, and 9, with
a mean of 7.6.


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