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ARRL Propagation Bulletin ARLP019 (2018)

ARLP019 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 19  ARLP019
From Tad Cook, K7RA
Seattle, WA  May 11, 2018
To all radio amateurs 

ARLP019 Propagation de K7RA

Sunspots reappeared this week, after none on April 28 through May 3.
Average daily sunspot numbers increased from 3.6 (last week) to 14.6
(May 3-9).

So far in 2018 56% of days were spotless. For all of 2017 the rate
was about half or 28%, for the whole year, a total of 104 days.
These numbers are according to .

Seemingly counter-intuitively considering the slight rise in sunspot
numbers, yet not unusual, average daily solar flux declined one
point from 69.3 to 68.3.

Solar activity continues to decline, and we've been expecting (over
the past few years) solar minimum to arrive about two years from now
in 2020.

But some have suggested that perhaps the decline is currently faster
than anticipated. I like to imagine a sooner minima could precede a
faster rise in the next cycle! What if the upcoming Cycle 25 echoes
Cycle 19? Sorry, no scientific evidence, but I like to dream this
could happen.

Cycle 19 was the largest in recorded history, and I would be glad to
see another one, just so it isn't accompanied by a Carrington Event.
The Carrington Event happened in September 1859 and produced solar
flares so powerful that telegraph offices, connected by long lines
acting as antennas, caught fire. But the peak of Cycle 19 happened
about 100 years later. reports this week that the American Geophysical
Union ( in a paper published May 10, researchers from the
University of Birmingham use Extreme Value Theory to estimate the
average time between "Carrington-like flares."


Tough to predict, but they estimate one every 100 years. Of course,
this means we are long overdue, but perhaps this is like the
gambler's fallacy: don't bet on red just because the last five spins
of the wheel landed on black:

According to
on page 11, smoothed solar flux numbers around 63 are predicted
toward the end of 2019. But when we observe numbers around the last
solar minimum (right now I am looking at the 109 days ending on
October 9, 2008 as an example) there were numerous consecutive
periods of no sunspots (average daily sunspot number during that
time was only 1.046) but average daily solar flux was 66.4, several
points higher than values predicted for the end of 2019.

These long term predictions are updated about every four weeks, but
I have no idea when predictions for 2020 will appear.

Predicted solar flux is 69 on May 11-12, 68 on May 13-15, 67 on May
16-18, 72 on May 19-25, 70 on May 26, 68 on May 27 through June 8,
and 70 on June 9, 72 on June 10-21, 70 on June 22 and 68 on June

Predicted planetary A index is 8 on May 11, 5 on May 12-16, 12 on
May 17-18, 8 on May 19, 5 on May 20-31, then 18, 25, 20, 16, 12 and
8 on June 1-6, 5 on June 7-12, then 42, 12, and 8 on June 13-15 and
5 on June 16-24.

Jon Jones, N0JK on May 5 sent in a message titled "Six meters comes
to life."

He writes,

"The summer 2018 sporadic-E season is underway in the northern
hemisphere. On May 4 the 50 MHz band was open most of the day across
North America and the northern Caribbean. At 1820z May 4 I was able
to work K7BHM DM43 AZ from my car on 50.125 MHz during a work break.
I was running 10 W on SSB to a 1/4 wave whip and received a 5x5
report. Most of the activity I saw spotted was FT8 on 50.313 MHz,
but still a lot of legacy SSB activity. The most interesting spots I
saw were for the OA4B/b 50.036 MHz. The beacon was spotted along the
eastern seaboard as far north as VE2XK in Quebec. At 2043z saw N5LJL
em26 spotted it. I listened from my car and had solid copy on OA4B/b
at 2050z, 5,980 km on a mobile whip. Propagation likely multi-hop

Last Friday, Tom Scott, N5GIT sent this 6-meter report:

"Greetings from South Texas!  Been a long time since I emailed (10
years when I was AD5FD) but here I am.

"6 meters really surprised several of us around here as we were able
to copy the TG9ANF beacon in Guatemala. No grid square was copied (I
have an audio file).  Especially me, because I was copying with a
long wire tossed over the railing of my second story balcony!  I
promptly logged XE1AO, DL89 off that same wire!  Sounds like 6 is
off to a great start. 73 de N5GIT, Tom Scott, EL09 in San Antonio."

F.K. Janda, OK1HH of the Czech Propagation Interested Group sends
his geomagnetic activity forecast for the period May 11-June 05,

"Geomagnetic field will be:
Quiet on May 27-29
Quiet to unsettled on 14-15, 24, 30,
Quiet to active on May 12-13, 19-23, 25, 31,
Unsettled to active on May 11, 26, June 3-4
Active to disturbed on May 16-18, June 1-2, (5)

"Solar wind will intensify on May (11,) 17-18, (19-20, 25-27, 31,)
June 1-2, (3-4)

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

New space weather observations and a video from Dr. Tamitha Skov.

"Dear Tad,

"There has been a recent uptick in solar activity over the past few
weeks that reminds us how variable Space Weather can be, even near
solar minimum. The last two solar storms have brought aurora as far
south as Colorado, Indiana, Germany, and the Netherlands. It's also
brought views high in the southern skies over New Zealand and
Tasmania.  Whether or not these moderately strong solar storms will
continue through the next few years as we cross through solar
minimum and begin to ascend into the new solar cycle is yet to be
seen. I, for one, hope so.

"This week, we have three new bright regions gracing the
Earth-facing Sun. One of these regions even launched a solar storm
on the Sun's backside. Not bad for a supposedly quiet Sun! This
week's forecast highlights these regions and the boost in
communications we are enjoying right now on the amateur radio bands.
It also highlights some of the amazing aurora photographs reported
during the recent solar storm. It shows how active our star can be
and just how quickly things can change.

"Cheers, Tamitha."

Nothing to do with propagation, but I found this article by KG4CUL
about Amateur Radio under the Third Reich fascinating:

Bruce is an Associate Professor of German Studies at the College of
William and Mary:

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 3 through 9, 2018 were 0, 13, 14, 14, 14,
25, and 22, with a mean of 14.6. 10.7 cm flux was 66.5, 67.8, 67.6,
67.2, 69.6, 69.6, and 69.6, with a mean of 68.3. Estimated planetary
A indices were 4, 4, 20, 31, 17, 14, and 16, with a mean of 15.1.
Estimated mid-latitude A indices were 3, 4, 12, 24, 14, 12, and 13,
with a mean of 11.7.


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