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ARRL Propagation Bulletin ARLP010 (2017)

ARLP010 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 10  ARLP010
From Tad Cook, K7RA
Seattle, WA  March 10, 2017
To all radio amateurs 

ARLP010 Propagation de K7RA

Over four days last week, we saw a blank Sun, starting with March 4.
On March 5 the sunspot number was 11 (indicating a single sunspot),
then on March 6-8 the Sun was blank again. Thus we saw an average
daily sunspot number of just 14.1, a 20-point drop from the previous
seven days.

Yesterday (Thursday) still no sunspots (our reporting week for
calculating averages runs Thursday through Wednesday, so the zero
sunspot number for Thursday will be included in the average for the
March 17 Propagation Forecast Bulletin).

Average daily solar flux decreased by seven points from 81.3 to

Geomagnetic indicators increased, with average planetary A index
rising from 13.1 to 20.9, and mid-latitude A index went from 8.7 to

Predicted solar flux is 71 on March 10-12, 73 on March 13-16, 76 on
March 17, 78 on March 18-23, 76 on March 24, 75 on March 25-29, 73
on March 30 through April 5, 72 on April 6-7, 74 on April 8-12, 76
on April 13, and 78 on April 14-19.

The planetary A index outlook shows 10 on March 10-11, 8 on March
12-15, then 20, 15, 10 and 8 on March 16-19, then 5, 8, 10, 15 and 8
on March 20-24, 5 on March 25-26, then 12, 35, 30, 20, 18, 12 and 8
on March 27 through April 2, 5 on April 3-4, 8 on April 5-6, 5 on
April 7-10, then 10, 20, 15, 10 and 8 on April 11-15, and 5, 8, 10,
15 and 8 on April 16-20.

Geomagnetic activity forecast for the period March 10-April 5, 2017
from F.K. Janda, OK1HH of the Czech Propagation Interest Group.

"Geomagnetic field will be:
Quiet on March 14-15, 21, 26
Mostly quiet on March 10-13, 20
Quiet to unsettled March 16, 22, 25, April 4
Quiet to active on March 18-19, 24, 27-29, 31, April 1-3, 5
Active to disturbed on March 17, 23, 30

Amplifications of the solar wind from coronal holes are expected on
March (20-22,) 23-27, (April 3-8)

- Parenthesis means lower probability of activity enhancement and/or
lower reliability of prediction."

Jon Jones, N0JK sent a tip about a 10-meter opening last weekend
from 1809-1839 UTC:

"There was an unusual 10 meter opening in the ARRL DX SSB contest
last weekend between Bermuda and W1, W2, W3 and W4 early Sunday
afternoon. Kurt, VP9/W6PH, was in Bermuda at VP9GE's station for the

"Kurt related, 'I decided to listen to the beacons on 10 Meters and
heard one in FN32. I decided to try a CQ on 28.401 MHz, Lo and
behold; a very loud K3OO came back to me and said he saw the blip on
his panadapter.  He said he would spot me and that started the ball

"Kurt then made over 400 contacts on 10 Meter SSB with strong
signals. The distance, high signal strength and time of day suggest
the propagation was one hop sporadic-E. Kurt noted no contacts to
the west coast of North America on 10, which would have been
F-layer. Sporadic-E occurs in March, though it is rare. The month of
March has the lowest amount of sporadic-E propagation of any month
in North America. The 10 meter sporadic-E opening was an unexpected
treat for Kurt and significantly helped his score."

Jon sent a map from showing the impressive opening from
1809-1839 UTC on March 5. It showed a tangle of contacts from North
America to Caribbean, but I redid it on the web site
specifying a World Map, and it showed contacts all the way down to
54 degrees south latitude, around the southern tip of South America.
Try it out yourself.

David Moore sent a photo taken in Norway of an aurora that was gone
in about ten seconds!

See it on the web at,

W9WS sent this article about an experiment regarding space weather
on the International Space Station.  I'm pretty sure that the Steven
Powell mentioned in this article is N2BU:

Stan Tacker, N5OHM wrote:

"Always appreciate your info.  Yes 10m has been opening up from NA
to SA.  Window is usually short, but when it is open, it's
gangbusters.  Reminds me of the days when guys ran scanners
monitoring 10m repeaters to hear the band open up."

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
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 2 through 8, 2017 were 52, 36, 0, 11, 0,
0, and 0, with a mean of only 14.1. 10.7 cm flux was 79.1, 78, 75.2,
72.8, 72.4, 71.7, and 70.6, with a mean of 74.3. Estimated planetary
A indices were 32, 22, 22, 17, 25, 16, and 12, with a mean of 20.9.
Estimated mid-latitude A indices were 23, 15, 18, 11, 16, 13, and 9,
with a mean of 15.


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