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ARRL Propagation Bulletin ARLP020 (2018)

ARLP020 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 20  ARLP020
From Tad Cook, K7RA
Seattle, WA  May 18, 2018
To all radio amateurs 

ARLP020 Propagation de K7RA

Weak solar activity continues, with sunspots returning on May 4-14,
then gone again. From the previous seven days May 3-9, average daily
sunspot number declined from 14.6 to 6.4 while average daily solar
flux increased from 68.3 to 70.2.

Earlier in the week geomagnetic indicators showed unrest from a
solar wind stream. Average daily planetary A index declined to 8.4
in this recent reporting week compared to 15.1 over the previous
seven days. Mid-latitude A index declined from 11.7 to 9.

Predicted solar flux is 69 on May 18-20, 68 on May 21-25, 70 on May
26-29, 68 on May 30 through June 2, 70 on June 3-8, 71 on June 9-14,
70 on June 15-25, 68 on June 26-29 and 70 on June 30 through July 1.

Based on this forecast, perhaps sunspots may return on May 26 or
June 9. May 26 is when predicted solar flux is expected to rise to
70, then after declining again, on June 9 flux is predicted at 71.

Predicted planetary A index is 14 and 8 on May 18-19, 5 on May
20-31, then 18 and 28 on June 1-2, 16 on June 3-4, then 14, 12 and 8
on June 5-7, 5 on June 8-12, then 18, 15, and 10 on June 13-15, 5 on
June 16-27, then 18 and 28 and on June 28-29 and 16 on June 30
through July 1.

F.K. Janda, OK1HH writes, in his geomagnetic activity forecast for
the period May 18-June 12, 2018, the geomagnetic field will be:

"Quiet on May 27-29, June 8-9
Quiet to unsettled on 24, 30, June 7, 10-12
Quiet to active on May 19-23, 25, 31, 6
Unsettled to active on May 26, June 3-5
Active to disturbed on May 18, June 1-2

Solar wind will intensify on May (18-20, 25-27, 31,) June 1-3, (4-8)

- Parenthesis means lower probability of activity enhancement.
- Forecasts remain less reliable"

From Dr. Tamitha Skov:

"Dear Tad,

"I have to share with you something important. As you likely know, I
have been working with the American Meteorological Society to create
a professional Space Weather certification. Such a certification
will cement this emerging field by giving weather broadcasters the
tools they need to bring Space Weather into our living rooms. Over
the past week, we have taken a big step forward in this endeavor.
The committee I am leading is now being officially asked to help
Universities offer the specialized training that will most benefit
weather broadcasters and the public.

"This couldn't come at a better time. Today, as I look on Space
News, I see yet another billionaire investing $32 million in deep
space communications networks for the commercial space industry.
Just like the dot-com boom at the turn of the century, more and more
angel investors are seeing the future of asteroid mining and space
tourism as having the potential to be extremely lucrative. But what
they don't yet know is how important Space Weather will be to their
very livelihoods.

"We may be dealing with a quiet Sun this week, but the Space Weather
remains busy. This is why its so important we have Space Weather
forecasts. In this week's video, I go over the short blast of fast
solar wind that could bump us back into active conditions over the
next day or two.  Aurora photographers will need to stay on their
toes! The Sun also keeps amateur radio operators happy as a new
bright region rotates into Earth view. This region has boosted the
solar flux and will keep radio propagation at marginal levels on the
Earth's day side easily over the next three days. That sure is a lot
of activity for a spotless Sun!

"Cheers, Tamitha"

Her latest video:

David Greer, N4KZ of Frankfort, Kentucky offers excellent commentary
on activity in seemingly dead bands:

"I know many hams find the current state of HF propagation to be
depressing -- particularly on the higher bands. But I take an
opposite view.  Often, I am pleasantly surprised by the SSB contacts
I can make on bands that sound dead -- but are not always as bleak
as they first seem.

"I like to work phone on 17 meters and higher. Many afternoons when
I get home from work a little after 2100 UTC, the higher bands sound
dead. But I use a pre-recorded 30-second CQ I recorded on my Icom
IC-7300's SD card to make some noise. And often I get an answer. But
if I don't, I keep hitting the play button and let the rig call CQ
and save my voice. I rotate my beam around to the various headings
and sometimes I get at least one unexpected surprise.

"On several recent afternoons, when I heard no signals on 17 meters
I have experience openings from my central Kentucky QTH to Portugal,
Spain or France between 2100 and 2200 UTC. And signals are often
strong -- S9 plus. A recent 45-minute long QSO with F5RAG on 17
meters in the late afternoon produced SSB signals so strong it
seemed as if we were talking across town on 2-meter FM simplex. A
number of stations from Portugal and Spain have found their way into
my log recently. Most say the same thing -- I'm the only stateside
signal they're hearing. As to whether that's because of propagation
favoring my part of the USA, or my being one of the few stations
'silly' enough to even try to make contacts under such adverse
conditions or my hilltop QTH with sloping terrain, I don't know.

"But Western Europe isn't the only place I've worked recently,
Twice, H44MS, Bernard, in the Solomon Islands, has called in off the
back of my log periodic when it was pointed toward Europe.

"I also have had some luck on 'dead bands' working into South
America on 15 and 10 meters about the same time of day. I'm fairly
sure TEP (Transequatorial Propagation) accounts for those QSOs.

"I do have days in which I CQ repeatedly on 17, 15 and 10 meter SSB
for an hour or more and come up empty-handed. But on at least half
of the days, a DX station replies. And I don't ignore 12 meters.
It's yielded the occasional QSO into VK or ZL on a 'dead band.'"

"I know the guys working the new FT8 mode are having some real
success in QSOing on so-called dead bands via scatter propagation. I
operated a bunch of JT65 and FT8 when the latter mode first became
popular -- their ability to dig out weak signals is impressive --
but I found myself bored with them and returned to my SSB and CW

"I encourage other ops to try the 'dead bands' -- particularly from
2100 to 2200 UTC. You just never know until you try."

Might be interesting, but the original text is elusive, even though
it was published in the past few months:

Full text expected at, but nothing there:

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 bat

Sunspot numbers for May 10 through 16, 2018 were 11, 11, 12, 11, 0,
0, and 0, with a mean of 6.4. 10.7 cm flux was 69.6, 70.3, 69.8,
70.9, 70.3, 70.3, and 69.9, with a mean of 70.2. Estimated planetary
A indices were 12, 16, 10, 8, 5, 4, and 4, with a mean of 8.4.
Estimated mid-latitude A indices were 11, 19, 10, 10, 5, 5, and 3,
with a mean of 9.


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