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ARRL Propagation Bulletin ARLP021 (2018)

ARLP021 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 21  ARLP021
From Tad Cook, K7RA
Seattle, WA  May 25, 2018
To all radio amateurs 

ARLP021 Propagation de K7RA

Sunspot activity resumed this week, after no sunspots for seven
consecutive days.  Average daily sunspot number was 7.7, rising from
6.4 in the previous reporting week.  Average daily solar flux was
70.1, changed little from 70.2 last week.

According to, in 2018 56% of days so far have been

Currently sunspot group 2710 and 2711 are active (2711 is growing),
and 2712 is about to emerge beyond the horizon.  On May 23 50
one-millionths of the visible solar surface was covered by sunspots.
April 24 and 25 was the last time this level of activity was seen.
On April 21 and 22 the sunspot area numbers were 120 and 130.

Average daily planetary A index and mid-latitude A index were both
5.3, down from 8.4 and 9 the previous week.

Due to an error at NOAA, the mid-latitude A index for Tuesday was
previously reported on Wednesday as 55.  This did not make sense to
me, as no other magnetometers reported such huge activity.  I sent a
couple of emails to various contacts at NOAA, and AD0IU got it
fixed.  This changed both the mid-latitude A index and planetary A
index for the day.

Predicted solar flux is 74 on May 25 to 27, 73 on May 28, 72 on May
29 to June 1, 70 on June 2 to 6, 68 on June 7 to 16, 69 on June 17
to 20, 70 on June 21 through July 3, and 68 on July 4 to 8.

Predicted planetary A index is 5 on May 25 to 27, 8 on May 28, then
5 on May 29 through June 1, then 28, 16, 16, 14, 12 and 8 on June 2
to 7, 5 on June 8 to 12, 8 on June 13, 5 on June 14 to18, then 16,
12 and 8 on June 19 to 21, 5 on June 22 to 27, then 16, 26, 16, 14,
12, 12 and 8 on June 28 through July 4, and 5 on July 5 to 8.

The above solar flux and planetary A index predictions are updated
daily at .

VK5EEE, Louis Szondy of Findon, South Australia reminds us:

"I read with interest the comments of N4KZ on 'seemingly dead bands'
and I'd like to remind your readers about the beacons that cover the
world on the 20, 17, 15, 12 and 10 meter bands.  I think many hams
either don't know about, or have forgotten about those beacons, or
because they are in CW they think it will be hard to know which is
which, but thanks to the Internet it is easy: the website shows
exactly which beacon is transmitting and where.  So to remind
readers, the IBP International Beacon Project has 18 beacons spread
out around the world, transmitting for 10 seconds each taking turn,
sending call sign and first dah at 100W, then second dah at 10W,
third at 1W and 4th dah at 100mW, in each case to an omnidirectional
ground plane antenna.  Therefore once every three minutes the same
beacon transmits again on the same frequency.  By listening for 3
minutes on 14100, 18110, 21150, 24930 and/or 28200 it is easy to
know which parts of the world are open to your QTH, and if you do
not know Morse Code you can see which one is transmitting live on
this page, provided your computer clock is accurate:

Bear in mind these beacons are 100W to a ground plane, even two
dipoles broadside to each other at a sufficient height, let alone
beams, would improve signal strength considerably between yourself
and that location."

Excellent reminder!  Thank you, Louis!

Mark Lundy, WD4ELG noted on May 22:

"20 meters FT8:  Tonight I heard UA9, 5T2, PY7, KH6, KL7, DL, ZL,
VK.  Just by calling CQ, I worked ZL2, VK7, EA9, CT2, HB9, DJ9, and
F8.  Hex beam and 50 watts.
Also active: UK9, AP2, VU2, JA, FK8, A9, KL7, tons of EU and SA.  I
don't remember a collection of DX like this at the same time since
the late 70's.  Probably possible to work DXCC on 20 meters FT8 with
some less-common entities in 24 hours if somebody knows what they
are doing.
Sunspots?  No.  What we need is ACTIVITY!  Hams on the air.  And
that's what FT8 has enabled to happen!"

"I was also simultaneously calling CQ on 30 and 40 at 0300 UTC, with
5 watts and dipoles on those bands, and getting EU DX calling me
back there as well."

Larry Godek, W0OGH of Cochise, Arizona wrote on May 20:

"Dead bands or poor propagation?  There have been some days when the
bands were 'dead'!  Nothing heard and it affected 40 and everything
above 17M here in SE Arizona during the day.

I was reading some old 1979 QST magazines the other day, kinda
refresh my memory of where we came from and ran across an article
from Russian ham about HF ducting.  Kind of interesting and I think
that may have occurred when I worked 3B7A on 40 SSB.  It's happened
on other occasions as well mainly with hard to work DX stations.
A52SV on 15M is another one that comes to mind.  The story is a bit
long so probably shouldn't go into it here but if you have your 1979
issues of QST around look thru them for the article.

3B7A, I had one last chance and that was Saturday afternoon,
evening.  I had been outside working and figured it was time to go
check out the bands looking for 3B7A.  15, 20 and 17M had delivered
nothing, a few minutes' worth on 17 SSB at one time but that was it.
They were working 40M ssb as usual so I figured I'd listen for a
bit.  Pretty soon I wasn't hearing any other stations and he was
calling CQ with no response.  I gave him a shout, took 3 calls but
he finally came back to me.  WHOT?  I run a K3 at 100W and the
antenna was a 40M inverted V up about 18 feet fed with 125 ft of
LMR-400.  They are confirmed in LoTW as well as Clublog so I can now
relax a bit.

Yesterday on 20M digital(FT-8) mode, well it was a bonanza for me
here in the high desert.   CT3HF, YT3PL, CT1LT, YB1RUS, YB5BOY,
9K2NO, a bunch of Russian stations, HZ1FI, 3D2AG, VK and ZL's,
numerous JA stations,  YB0OHG, FK8DD, VK0AI, BX2AFU, XV9NPS, BD7BS,
HP1AVS, S51ZZ, LA1PHA, GM3VFR, OM5XX and EA9ABC.  Lots of new stuff.
50W and a Yagi at 40 ft.  Ya gotta be there when the band is hot!  I
see folks calling AP2NK but I never see a trace of him.

W0OGH, somewhere in Cochise County, Arizona, DM52ba"

"Geomagnetic activity forecast for the period May 25 to June 19, 2018
Geomagnetic field will be:
Quiet on May 25, 30, June 8 to 11, 13 to 17
Quiet to unsettled on May 26, 31, June 7, 12
Quiet to active on May 29, June 6
Unsettled to active on May 27 and 28, June 3 and 4, 18
Active to disturbed on June 1 and 2, (5, 19)

Solar wind will intensify on May (25 to 27, 31,) June 1 to 3, (4 to
8,) 19

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

F.K. Janda, OK1HH"

From Tamitha Skov:  

"Dear Tad,

This week we get a real treat.  A new active region has rotated into
view with a magnetic configuration that is twisted up like a
pretzel.  On the Sun, things that are twisted up usually don't stay
that way for long.  They release all that tension in a jolting burst
of energy.  (Sort of sounds like life, doesn't it?)  Those jolts of
energy are solar flares and they help to reconfigure and relax the
solar pretzel.  However, they often come with little warning.  In
less than three days we have gone from a very quiet Sun to one that
has fired multiple C-class flares and has us forecasters flirting
with the idea of raising the M-flare risk!  On top of that, solar
flux has been boosted to levels we haven't seen in months.  I've
even heard from amateur radio operators, who have told me they are
firing up their rigs for the first time in months, excited they
might actually make contacts denied them this entire year!

In the forecast video this week, I discuss how we are keeping a
close eye on this new activity.  As anticipated, today NOAA named
the new region 2712 (that is why I had it in parenthesis in the
video) and they are upping the C-flare risk to 25% for the day.
This means we will likely see more flare activity before things
settle down.  If this region remains active for a few more days, it
has the possibility of firing a solar storm while in the
Earth-strike zone.  Chances for this are slim, but it's always a
possibility.  Overall, this is turning out to be a very exciting


Her latest weekly video:

For more information concerning radio propagation, see the ARRL
Technical Information Service 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 May 17 through 23, 2018 were 0, 0, 0, 0, 12, 12,
and 30, with a mean of 7.7.  10.7 cm flux was 69, 69.4, 70.3, 68.8,
69.6, 70.8, and 73.1, with a mean of 70.1.  Estimated planetary A
indices were 10, 4, 3, 3, 3, 5, and 9, with a mean of 5.3.
Estimated mid-latitude A indices were 9, 3, 3, 3, 3, 6, and 10, with
a mean of 5.3.


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