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ARRL Propagation Bulletin ARLP031 (2016)

ARLP031 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 31  ARLP031
From Tad Cook, K7RA
Seattle, WA  July 29, 2016
To all radio amateurs 

ARLP031 Propagation de K7RA

Reporting this week from the Hill Country of West Texas, Kerrville,
northwest of San Antonio. Happy to report that the food is
delicious, the locals very friendly and hospitable, and gas costs
only two bucks a gallon. Speed limit on the highways is 75 MPH, and
it seems almost like the 1970s again.

We have fallen back to a period of 0 sunspots, so far only lasting
three days. This was after a brief uptick in solar activity from
July 15-21. But looking at the STEREO site at we can see that on the opposite side of
the Sun there are still sunspots, which should drift back into view
as our Sun rotates relative to Earth in a couple of weeks.

After those three blank days, the sunspot number rose to 13 on July

Average daily sunspot number declined from 58.1 to 19.3 (comparing
the July 21-27 period to the previous seven days), and average daily
solar flux from 103.6 to 82.5. Average daily planetary A index went
from 10.6 to 8.7, while the mid-latitude A index declined from 11.1
to 8.9.

Predicted solar flux from USAF and NOAA space weather observers is
70 on July 29 to August 3, 75 on August 4, 80 and 95 on August 5-6,
105 on August 7-16, then 100, 90, 85 and 80 on August 17-20, then 75
on August 21-22, and 70 on August 23-31. Solar flux the goes to 105
on September 3-11.

Predicted planetary A index is 10 and 8 on July 29-30, 5 on July 31
to August 2, 20 on August 3-4, 15 on August 5, 10 on August 6-7,
then 20, 8, 12, 10 and 8 on August 8-12, 5 on August 13-14, then 8,
12 and 5 on August 15-17, 8 on August 18-19, then 5, 8, 15, 12, 8,
20, 12 and 8 on August 20-27 and 5 on August 28-29, 20 on August
30-31, 15 on September 1 and 10 on September 2-3, then 20, 8, 12, 10
and 8 on September 4-8.

At 0537 UTC on July 28, 2016 the Australian Space Forecast Centre
issued a geomagnetic disturbance warning:

"Elevated geomagnetic activity possible due to the expected arrival
of a high speed solar wind stream from a coronal hole on 28 July.


"GEOMAGNETIC ACTIVITY FORECAST 28 Jul:  Unsettled to Active,
possible Minor Storm periods 29 Jul:  Quiet to Unsettled, possible
Active periods"

Petr Kolman, OK1MGW of the Czech Propagation Interest Group sent us
this forecast:

"Geomagnetic activity forecast for the period July 29-August 24, 2016,

"Geomagnetic field will be:
Quiet on August 23-24
Mostly quiet on August 1-2, 12-14, 17-18, 22
Quiet to unsettled on July 31, August 5-7, 10-11, 19
Quiet to active on July 29-30, August 3-4, 8-9, 15-16, 20-21
Active to disturbed on August (3-4)

"Increases in solar wind from coronal holes are expected: July
29-30, August 2-4, 7-9, 20-21.

"Parenthesis (August 3-4) means lower probability of activity

"Petr Kolman, OK1MGW (OK1HH and OK1MGW, weekly forecasts since
1978)" reported: "Earth is entering the outskirts of a
broad stream of debris from Comet Swift-Tuttle, source of the annual
Perseid meteor shower. Forecasters don't expect the shower to peak
until August 11-13, but already NASA cameras are detecting Perseid
fireballs streaking across the night sky as the shower slowly
intensifies." Meteor trails can enhance propagation.

David Moore reported, "Sun blasts out 2016's strongest solar flare."
It can be see at,

Scott Bidstrup, TI3/W7RI sent this from Costa Rica:

"Here is an article that some of your readers might find interesting
about how scientists are discovering that the details of how the
solar wind powers auroras are a bit different than had been thought.
New satellite data might lead to improved auroral forecasts:


"Been awhile since I've sent in a report on propagation from here in
the single-digit latitudes, so here goes.

"On 6 meters, there's only been two really good openings into the
States of any consequence, one on the 14th of June, another on the
12th of July, and so far, no openings at all into the South Pacific
or Europe, which is strange, because they're normally common here.
So far, I have yet to hear Remi in New Caledonia, and I usually hear
him several times per week.

"The opening on the 12th into the States was a really spectacular
one; I got 76 QSOs in the log, easily the best opening since I've
been down here in Costa Rica, mostly working the East Coast, but
occasionally into the Midwest, as far west as Denver. Worked my
first VEs on 6 from here, and got two of them, a half hour apart.

"Everybody's really been singing the blues around here about the
lack of openings otherwise, though. Even the nightly TEP openings
into South America that are a usual feature of 6 meters this time of
year here, have simply not been happening at all. I've only heard
those familiar watery signals twice so far this year, and even then
the signals weren't particularly strong, nor were they to any
stations I haven't already worked many times.

"The frequent, almost daily Es openings into Venezuela and French
Guiana we enjoyed last year are only a memory so far this year. If
low-latitude sporadic-E is supposed to be correlated with low solar
activity, you couldn't have proved it by me.

"The HF bands are also suffering from the lack of solar activity.
The higher bands, 20m-10m have seen noticeably weaker signals, with
propagation entirely absent on 10m for days at a time, and only a
very few weak signals on 15.

"That's ominous, because even during the last solar minimum, there
would be a decent, if brief opening on 15m most days, and afternoon
TEP on 10m into South America was a daily occurrence. But it is not
happening at all so far this year. Most of my HF activity has been
on 20m just because there hasn't been any other choice. Even 17m
hasn't been an option.

"The low bands, too, are affected down here by all this. My local
gringo friends and I usually have an early morning coffee klatch on
75m between 5 and 6 AM, and until recently, the signals, as soon as
we would get on, were strong and stable as one would normally expect
on that band.

"But lately, the band has been shortening up for local paths quite a
bit later than it ever has in the past - often not until an hour or
so after sunrise. At times, the propagation on 75 has been so long
that Stateside QRM has been stronger than our local Central American
stations. Jay, HP3AK, reports that this has been great for his
morning gray-line 75m DXing, especially into VK/ZL, but it has
shortened up our morning coffee klatch by a half hour or more,
because we just can't make ourselves heard locally early.

"This strange propagation seems to be an issue on 40m as well, which
often isn't opening up for regional short skip until as late as 9 or
even 10 in the morning. It's really bizarre - never seen anything
quite like it, even during the last solar minimum. In the past, 40m
here has always been open as soon as the sun was up.

"I've noticed that these really late openings on the low bands seem
to be correlated with really low 304 angstrom UV index numbers. I'm
noticing that the current SOHO 304a number is very close to the
lowest I've ever seen it (a few weeks ago, it was the lowest), even
during the last solar minimum. I'm wondering if that's real or if
it's degradation of the sensor on the satellite. Judging from how
the bands have been behaving, it must be real."

I've been intending to run this for weeks, but it keeps falling off
the agenda. Notice how there are progressively fewer sunspots, as
the record transitions from April 2014 to April 2016 and the months

And finally, I'm unsure who sent this (David Moore?) but one reason
I found it interesting is personally I cannot imagine being shut
inside a capsule and hurtled through some vast void.

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

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bulletins are at

Sunspot numbers for July 21 through 27 were 49, 36, 34, 16, 0, 0,
and 0, with a mean of 19.3. 10.7 cm flux was 100.1, 90.4, 86.2,
82.2, 73.6, 73.5, and 71.6, with a mean of 82.5. Estimated planetary
A indices were 5, 8, 8, 14, 18, 5, and 3, with a mean of 8.7.
Estimated mid-latitude A indices were 6, 8, 10, 12, 15, 7, and 4
with a mean of 8.9.