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Friday, March 31, 2017

ARRL Propagation Bulletin No. 0013

ARLP013 Propagation de K7RA
Propagation Forecast Bulletin 13  ARLP013
From Tad Cook, K7RA
Seattle, WA  March 31, 2017
To all radio amateurs
ARLP013 Propagation de K7RA
Solar activity rose over the past week, with average daily sunspot
numbers rising from 3.4 to 29.7 and solar flux from 71.2 to 77.9.
Average daily planetary A index increased from 10 to 18.3, and
average mid-latitude A index went from 7.1 to 13.6.
Predicted solar flux is 86, 87 and 88 on March 31 til April 2, then
86, 84, 83 and 82 on April 3 to 6, 71 on April 7 to 14, 73 on April
15 to 17, 75 on April 18 to 22, 78 on April 23 to 26, 75 on April 27
to 29, 73 on April 30 to May 1 and 71 on May 2 to 11.
Predicted planetary A index is 20 on March 31 through April 2, 15 on
April 3 and 4, 12 on April 5 and 6, 5 on April 7 to 16, then 24, 25
and 10 on April 17 to 19, 5 on April 20 to 22, then 25, 40, 35, 20,
18 and 12 on April 23 to 28, and 8, 16, 12, 15 and 12 on April 29
through May 3, followed by 5 on May 4 to 13 and 24 on May 14.
F.K. Janda, OK1HH sent us his geomagnetic activity forecast for the
period March 31 to April 25, 2017.
“Geomagnetic field will be:
quiet on April 9 and 10, 14 to 16, 20 to 22
mostly quiet on April 6, 8, 11
quiet to unsettled April 4, 12 and 13, 19
quiet to active on April 3, 5, 7, 23, 25
active to disturbed on March 31, April 1 and 2, 17 and 18, 24
Amplifications of the solar wind from coronal holes are expected on
March 31, April 1 to 4, (5 to 8,) 12 and 13, (14,) 16 to 20, 25.
– Parenthesis means lower probability of activity
enhancement and/or lower reliability of prediction.”
Tamitha Skov released a space weather video last week:
Jon Jones, N0JK reported:  “Aurora contacts reported on 6 meters
March 27 along the northern tier states and Canada.  This was due to
a G2 geomagnetic storm from coronal wind stream.”
Scott Bidstrup, TI3/W7RI sent this from Costa Rica:
“Don’t know if you’ve seen this, but a magnetic precursor event to
solar flares has been discovered, that may actually lead to
short-term warnings before a flare occurs.
The six meter drought that everyone has been complaining about up
there has been even worse for us down here in the single-digit
latitudes.  It’s been at least six months since I’ve logged a six
meter QSO.  In the wake of coronal hole passages, there have been a
couple of evenings recently with some very modest TEP openings from
here into Brazil and Argentina, but with only a small handful of
stations heard weakly and no new stations not already worked many
times.  There has been no sporadic E at all for many months – not
even hearing the beacons from Venezuela and French Guiana that
indicate our most common openings to the east.  If there is supposed
to be an inverse correlation between solar activity and sporadic E,
like the textbooks claim, you could have sure fooled me.
Not that there has been no sporadic E at all; indeed, there has been
very frequent Sporadic E openings into South America on 10m in the
daytime here, and even frequent evening TEP openings into South
America on 10m as well.  But the signals are about what we would
normally expect on six meter openings rather than ten.  MUFs from
these events just aren’t getting very far into the VHF.
Conventional F2 openings on ten have become very rare now.
Other propagation on the upper HF bands has been poor – the
declining solar activity has taken a big toll here on the upper HF
bands, with most band openings starting later in the morning than in
the past, and ending earlier in the late afternoon – and signals not
being particularly strong when the band is open.  The only saving
grace has been that our mid-day break has been shorter and weaker
than at the solar maximum, so it’s often possible to hear signals
and even work them at midday on 20m, which has not been possible at
higher sunspot numbers.  MUF has gotten high enough to open 17m on
most days, but often it doesn’t quite make it to 15m.  So when 15m
is open, it’s often the result of a weak sporadic E event or the
aftermath of a coronal hole passage.  During the last solar minimum,
15m would be open most days, but so far during this one, it’s been
hit and miss at best.  And the solar minimum is just getting a good
30m has been the most reliable performer – almost always open into
the States during the day and worldwide at night.  Sadly, PSK
activity seems to have declined on 30m, so I haven’t worked as many
stations with the ragchews I dearly love, just the spartan JT9
contacts.  Sure wish we had phone privileges on that band.
40m has been seeing a huge increase in QSO activity with conditions
on 20m declining.  There are evenings now where finding an open spot
can be a bit of a problem.  Most of what I hear on phone here is the
States, but I am seeing a lot of eastern European DX on PSK, and my
good friend, Michael, TI7XP, has worked some pretty good DX on 40m
CW in recent days, including Kuwait and several stations in the Far
East, and a lot of VK/ZL.  The DX here is definitely improving on
60m is still not available here, and all of us here are holding our
breath, waiting for a response from the FCC on the League’s petition
for rulemaking, allowing 100w. activity up there on the new WARC 60m
band.  If it happens for the States, it would be terrific news for
us – another piece of terrific ammunition in our fight to get access
to 60m here.  There are still no Central American countries that
allow access to 60m yet.  And I can’t see a good reason why not –
there is almost no local commercial or government activity in that
portion of the spectrum here.
80m is seeing an improvement, especially in DX as the solar activity
declines.  My good friend in Panama, Jay, HP3AK, is working Japan on
most morning greylines, and often getting quite good reports.  VK/ZL
is being worked more frequently, too – often several times per week.
And nighttime Old World DX is more frequently heard now than it was
just a year ago.  Several of my local friends report working Europe
with fairly modest 80m installations.  Signal levels from the
States’ 75m evening ragchews have been noticeably stronger than in
the past, too.  Nighttime D-layer hasn’t responded as much to the
rising cosmic ray flux as I would have expected by now.
Noise levels on 160m have been low enough this winter that some of
the locals are getting more interested in top band.  TI7XP has a new
skywire loop up for that band, and has worked some good DX on it.
But the summer noise season is just about here, and I don’t expect
the interest will last long.
And finally, I am pleased to report that I have copied four
experimental beacons on 630m from the States, and have sent the
corresponding WSPR decodes to the operators, who were delighted for
the reports from here.  Most nights, when noise levels aren’t
particularly high, I can hear at least one or two, with just a G5RV
at 50 feet and an ordinary IC7200 tuned to the appropriate
frequency.  Enough success to demonstrate that QSOs with Central
America from the States should be possible with modest stations on
that band.  Not much hope for 630m access here though, at least
until it has become a major band in the States like it now is in
Europe, so we can justify access to it here.  I have checked the
2190 band, but so far, I haven’t copied anything yet.”
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
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 March 23 through 29, 2017 were 12, 12, 11, 20,
49, 51, and 53, with a mean of 29.7. 10.7 cm flux was 72, 72.3, 74,
77.2, 82.8, 83.7, and 83.3, with a mean of 77.9.  Estimated
planetary A indices were 11, 6, 4, 4, 54, 28, and 21, with a mean of
18.3.  Estimated mid-latitude A indices were 9, 7, 3, 3, 34, 22, and
17, with a mean of 13.6.


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