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ARRL Propagation Bulletin ARLP028 (2015)

ARLP028 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 28  ARLP028
From Tad Cook, K7RA
Seattle, WA  July 10, 2015
To all radio amateurs 

ARLP028 Propagation de K7RA

Solar activity perked up over the July 2 to 8 period, with average
daily sunspot numbers increasing from 35.9 to 109.1, compared to the
previous seven days.
Likewise, average daily solar flux increased from 100.7 to 123.2.
Daily sunspot numbers were below 100 on June 16 through July 3,
bottoming out at 25 on June 27.
A moderate geomagnetic storm on July 4 and 5 was caused by a solar
wind stream.  The mid-latitude A index from Fredericksburg, Virginia
on July 4 to 6 was 21, 16 and 9.  The planetary A index, based on
observations from a number of Northern Hemisphere magnetometers was
19, 25 and 10 on those same days, and the college A index from
Fairbanks, Alaska was 13, 31 and 18.
The current outlook (on Thursday before the bulletin is published)
has predicted solar flux over the following seven days a bit weaker,
averaging 118.1, Thursday through Wednesday.
You can check how the daily 45-day forecast of solar flux has done
recently by going to and clicking "Download
this file."
The latest prediction from USAF/NOAA has solar flux at 125 on July 9
to 11, 122 on July 12, 120 on July 13, 115 on July 14 and 15, 125 on
July 16, 130 on July 17 and 18, then 125, 115, 110 and 105 on July
19 to 22, then 100 on July 23 to 26, then 105, 110 and 112 on July
27 to 29, 115 on July 30 and 31, 120 on August 1 and 125 on August 2
to 4.  Solar flux then peaks at 130 on August 10 to 14, then goes to
100 after August 18.
For planetary A index, the prediction is 12, 25 and 18 on July 10 to
12, 8 on July 13 and 14, 5 on July 15 to 17, 8 on July 18 and 19, 5
on July 20 to 25, 8 on July 26, 5 on July 27 to 30, then 18, 25 and
12 on July 31 through August 2, then 5 on August 3 to 5, then 20 and
25 on August 6 and 7, 8 on August 8 and 9, 5 on August 10 to 13, and
8 on August 14 and 15.
For the next few days USAF and NOAA predict the geomagnetic field at
quiet to active levels July 10, then unsettled to minor storm levels
on July 11, and unsettled to active levels July 12.  They see a
slight chance of M-class flare activity on July 10 to 12.
Australia's Space Weather Services at the Bureau of Meteorology in
Haymarket, New South Wales issued a geomagnetic disturbance warning
at 2316 UTC on July 9.  They said coronal hole effects starting late
July 10 are likely to produce active periods and storm levels at
higher latitudes on July 11.  They repeat that increased geomagnetic
activity is expected due to a coronal hole high speed wind stream
over July 10 to 12.  They see quiet to active conditions July 10,
unsettled to minor storm July 11, and unsettled to active conditions
on July 12.
By the way, all times expressed in this bulletin are in coordinated
universal time, so 2355Z is the same as 2355 UTC and 2355 GMT.  The
date relates to the clock also, so 2355Z on July 10 is 6 minutes
before 0001Z on July 11.
Petr Kolman, OK1MGW has his own geomagnetic outlook, and he predicts
the geomagnetic field will be quiet to unsettled July 10, active to
disturbed July 11, quiet to active July 12, quiet to unsettled July
13 and 14, quiet on July 15, mostly quiet July 16 and 17, quiet to
unsettled July 18, quiet to active July 19 to 21, quiet to unsettled
July 22 to 25, mostly quiet July 26 to 29, quiet to active July 30
and 31, quiet to unsettled August 1 and 2, and mostly quiet August 3
to 5.
Petr expresses some uncertainty about the active to disturbed
prediction for July 11, and suspects it may be like the following
day, quiet to active.  He also predicts an increase in solar wind on
July 10 to 12 and 30 and 31.
Ed Stratton, W1ZZ of Groton, Massachusetts in FN42ep, 30 miles NW of
Boston wrote: "I have been on 6 meters for a change of pace from HF
DXing.  In the past few days, from June 27 to July 5 I have logged
many W4s, W9s, and W5s, and several VO1s.
What is interesting is that there have been several openings to
Europe, usually starting around 2000z to about 2300z.  I have logged
both SSB and CW QSOs with PJs, YVs, 9Y4, CTs, MW, MI, MD, G, EI,
EAs, and an EA6.
My working conditions are 150 watts and a 5 element Yagi only 22
feet up, and just recently it was 'armstrong' rotated.  Now using a
rebuilt 30 year old TR44."
Check out photos of Ed's antennas at
Ken Jones, K1DAT lives in Millis, Massachusetts (FN42he) but
operates from a summer cottage in Sagamore Beach (FN41rt)
overlooking Cape Cod Bay.
Ken wrote, "I was at my summer cottage over the July 4 weekend and
missed a new grid square.
I was tuning around the CW end of six meters listening to an opening
to Europe when I heard 4X4DK calling CQ NA on 50.103.  I only heard
one other station calling him, like myself (5-7 times), but he
didn't hear us.
So, I posted him on a dx cluster and within 20-30 seconds there were
several stations calling him.  I only heard one station work him,
N3XX, and Ami had a hard time with the exchange.
I emailed Ami and he reported back that he did not hear me, seeing
my post he listened for me but had an S3-S5 noise level.  Maybe
that's why more people couldn't work him."
Curious about the N3XX antenna system, I (K7RA) emailed N3XX after
seeing photos of his antennas on his page.  Tim replied,
"The three pictures on my page are all of the same array,
just different views.  The array is 4x7 LFA (Loop Fed Array)
antennas, built for 6 meter EME, but works great for terrestrial
also.  There are two other taller towers here that support HF Yagis,
wires, and a 5 element 6 meter Yagi.
6 meter openings across the Atlantic have been pretty rare this
season from this part of the country.  Working 4X4DK was one of the
few bright spots, even though I had a few QSOs with him in past
years.  I didn't hear him for very long, but he was 559 when we
worked.  He had trouble hearing me though, and gave me a 439 report.
I haven't worked any new ones on 6 meters this season, but still
hoping for good things over the next few weeks."
You can read about Loop Fed Array Yagi antennas at , , and .
The IARU HF Championship is this weekend, and lasts for only 24
hours, 1200 UTC Saturday to 1200 UTC Sunday.  See for details.
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
Archives of the NOAA/USAF daily 45 day forecast for solar flux and
planetary A index are in downloadable spreadsheet format at and .
Click on "Download this file" to download the archive and ignore the
security warning about file format.  Pop-up blockers may suppress
download.  I've had better luck with Firefox than IE.
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 July 2 through 8 were 73, 91, 111, 131, 109,
118, and 131, with a mean of 109.1.  10.7 cm flux was 113.8, 112.3,
116.8, 124.8, 133.4, 132.6, and 128.9, with a mean of 123.2.
Estimated planetary A indices were 3, 3, 19, 25, 10, 5, and 5, with
a mean of 10.  Estimated mid-latitude A indices were 4, 2, 21, 16,
9, 5, and 5, with a mean of 8.9.


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