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ARRL Propagation Bulletin ARLP025 (2016)

ARLP025 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 25  ARLP025
From Tad Cook, K7RA
Seattle, WA  June 17, 2016
To all radio amateurs 

ARLP025 Propagation de K7RA

That was a little scary seeing the daily sunspot number at zero for
four days, June 3 to 6, but conditions seem to have recovered
Average daily sunspot number for this reporting week (June 9 to 15)
was 29.1, up from 7.7 the previous week.  The minimum non-zero
sunspot number is 11, due to the way sunspots are counted.  A
sunspot number of 11 does not mean there are 11 sunspots.  It means
there is one sunspot (counting as one point) in one sunspot group
(adding 10 points).  A second sunspot raises the sunspot number to
12, unless that spot is on its own and not clustered with the other
spot, in which case the sunspot number would be 22.  So that average
daily sunspot number of 7.7 from the previous week is due to the
fact that four out of the seven days had sunspot numbers of zero.
The rest were 27, 12 and 15.  You would never see a day with an
actual sunspot number of 7.7.
Average daily solar flux this week was 88.3, up from 80.7 last week.
I think the lowest solar flux number I've seen is 66.  Solar flux is
measured three times per day at 2.8 GHz in Penticton, British
Columbia.  The official number reported for the day is just the
reading at local noon.
You can see the thrice daily solar flux reading direct from Canada
at .
Predicted solar flux for the next month is pretty flat, at 88 on
June 17 to 23, 85 on June 24 to 30, 80 on July 1 to 5, 85 on July 6
to 9, 92 on July 10 and 11, 95 on July 12 to 18, 92 and 90 on July
19 and 20, 85 on July 21 to 27, and 80 again after July 27.
Predicted planetary A index is 8 on June 17 and 18, 5 on June 19 and
23, then 12 and 8, on June 24 and 25, 10 on June 26 and 27, 5 on
June 28 through July 1, then 25, 20 and 8 on July 2 to 4, 5 on July
5 and 6, 8 and 10 on July 7 and 8, 8 on July 9 and 10, then 5, 8, 12
and 8 on July 11 and 14, 5 on July 15 and 19, then 10, 12 and 8 on
July 20 and 22, 1 on July 23 and 24, and 5 on July 25 to 28.
You can see this same daily 45 day forecast of solar flux and
planetary A index, usually posted after 2100 UTC at .
Petr Kolman, OK1MGW sent this geomagnetic forecast.
Geomagnetic activity forecast for the period June 17 and July 13,
Geomagnetic field will be: 
Quiet on June 21 and 22 
Mostly quiet on June 19 and 20, 29 and 30, July 1, 5 and 6 
Quiet to unsettled on June 25, 28, July 4, 7, 10, 13 
Quiet to active on June 17 and 18, 23 and 24, 26 and 27, July 8 
and 9, 11 and 12 
Active to disturbed on June (18), July 2 and 3

Amplifications of the solar wind from coronal holes are expected on
June 17 and 18, 23 and 24, 26 and 27, July 2 and 3, 8 to 12.
(Parenthesis means lower probability of activity enhancement).
Petr Kolman, OK1MGW Czech Propagation Interest Group (OK1HH 
OK1MGW, weekly forecasts since 1978) e-mail:
In this Astrophysical Journal article, we see a study that tracks
geomagnetic numbers against the interplanetary magnetic field and
solar flux.  Is there a correlation?
Also check this one, which I hesitate to pass on since mention of a
Grand Minimum can generate so much fear and loathing:
Jon Jones, N0JK in em28 (Lawrence, Kansas) wrote:
"June 14 was a great day for the Caribbean, Central America and
northern South America from KS.  6 meters was open from 1530z or so
to after 2350z to these areas.  I listened to 6Y5WJ run a bunch of
Qs.  I had chased Jamaica for many years on 6, then work Josh with
one call at 2007z.  Heard him for hours.  Josh hit an honest 599.
I logged HH2AA at 1951z, who reportedly was running just 8 Watts to
a wire antenna.  Also worked John, FS/K9EL FK88 at 2031z.  As I was
watching our 5 year old granddaughter, I could not go out portable,
so used my dipole in the attic at 100 W.  I worked ZF1EJ earlier at
Later around 2300z P43A popped in big and loud on 50.115.  I worked
P43K at 0038z June 15.  P43A worked a bunch of stations from the
Midwest to east coast up to W1.  All of this was multi- hop sporadic
One of the best openings to these regions via Es in years."
For more information concerning radio propagation, see the ARRL
Technical Information Service 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
Instructions for starting or ending email distribution of ARRL
bulletins are at
Sunspot numbers for June 9 through 15 were 22, 28, 40, 39, 27, 26,
and 22, with a mean of 29.1.  10.7 cm flux was 85.2, 84.9, 88.2,
94.1, 91, 87.6, and 87.3, with a mean of 88.3.  Estimated planetary
A indices were 4, 9, 11, 10, 9, 21, and 14, with a mean of 11.1.
Estimated mid-latitude A indices were 5, 9, 11, 9, 10, 15, and 15
with a mean of 10.6.