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ARRL Propagation Bulletin ARLP014 (2018)

ARLP014 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 14  ARLP014
From Tad Cook, K7RA
Seattle, WA  April 6, 2018
To all radio amateurs 

ARLP014 Propagation de K7RA

We only saw sunspots over two days of this past week, March 30 and
31 when the daily sunspot numbers were 11 and 12.  There were no
sunspots during the previous week, so the average daily sunspot
number rose from 0 to 3.3.

Average daily solar flux changed from 68.2 to 68.6.

Geomagnetic indicators were quiet, with average daily planetary A
index declining from 10.6 to 5, and average mid-latitude A index
going from 8.9 to 4.

The averages for solar flux and A index shown at the end of last
week's bulletin were incorrect, and have been corrected above.
Thanks to AA2F for discovering my error.

Predicted solar flux is 67 on April 6 to 12, 68 on April 13 to 22,
69 on April 23 to May 6, 68 from May 7 to 19 and 69 on May 7.

Predicted planetary A index is 8 on April 6, 5 on April 7 to 9, then
on April 10, 15 on April 11 and 12, 18 on April 13 and 14, then 15,
10, 5 and 8 on April 15 to 18, 15 on April 19 to 21, then 12 and 10
on April 22 and 23, then 5 on April 24 to May 6, then 10, 15 and 20
on May 7 to 9.  18 on May 10 and 11, then 15, 10, 5 and 10 on May 12
to 15, then 15 on May 16 to 18 and 12 and 10 on May 19 and 20.

F. K. Janda, OK1HH sent this geomagnetic activity forecast for the
period April 6 to May 1, 2018.

Geomagnetic field will be:

Quiet on April 8 and 9, 24 and 25, 27 to 29, May 1
Mostly quiet on April 19, 26, 30
Quiet to unsettled on April 7, 10, 16 to 18, 23
Quiet to active on April 6, 11, 13, 15, 20 to 22
Active to disturbed on April 12, 14

Solar wind will intensify on April (6 to 8,) 10 to 18, 23 to 25, (27
to 30)

- Parenthesis means lower probability of activity enhancement.

Mark Bell, K3MSB of Airville, Pennsylvania reported on April 5:

"I've been trying to work Australia for quite a while on 160M.
During the current 160M season I've heard bits and pieces of calls
from VK land, and occasionally a complete call, but nothing strong
enough to work.

Saturday morning March 31 I was on 160M around 1030Z. I saw Ron
VK3IO spotted and tuned to his frequency and was astounded at his
signal strength!  He was at nice 559, almost armchair copy as the
saying goes.  I was even more stunned that he answered my first call
and received a 579 from him at 1045Z, which is about 35 minutes
before my sunrise.  At 1101Z I had the pleasure of working Luke
VK3HJ, who was not as strong as Ron but putting in a very nice
signal.  My receive antenna is a 200 foot RBOG (Reversible Beverage
On Ground) oriented NW/SE and my transmit antenna is an INV-L.

On Wednesday 4 April 160M was pretty dead around 1030Z so I started
calling CQ.  A few KHz above me, Jon AA1K was also calling CQ.  Phil
VK6GX spotted Jon at 1024Z and myself at 1033Z.  Later I emailed Phil
and he said while he heard us, we were both too weak for a QSO.

Phil also stated that openings from VK6 to the East Coast 'have been
few and far between in the last few years.  Signals often don't make
it across the Nullarbor Plain to VK6.' "

Interesting article on the history of solar photography:

From Tamitha Skov:

"Outside of the bright region this week being a lot quieter and
weaker than we hoped, we have a remnant coronal hole sending small
pockets of fast solar wind our way.  This is good news for aurora
photographers at high latitudes, but it also brings a little more
zing to the ionosphere for amateur radio operators and emergency
responders suffering with low solar flux right now.

Radio propagation on Earth's day side will likely remain poor, but
you might be surprised how a slight bit of activity can really perk
up the radio bands at night and in the gray line.  GPS users should
also enjoy better than average GPS conditions on Earth's night side,
even at low latitudes where night time is often troublesome for GPS.

But don't expect these conditions to last for more than a few days.
Next week we will be dealing with a more serious chance of reaching
solar storm conditions, when a much bigger coronal hole rotates into
the Earth-strike zone."

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 March 29 through April 4, 2018 were 0, 11, 12,
0, 0, 0, and 0, with a mean of 3.3.  10.7 cm flux was 69, 68.8, 69,
69, 68.4, 67.8, and 68.5, with a mean of 68.6.  Estimated planetary
A indices were 4, 5, 7, 5, 5, 4, and 5, with a mean of 5.  Estimated
mid-latitude A indices were 3, 4, 6, 4, 4, 3, and 4, with a mean of


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