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ARRL Propagation Bulletin ARLP009 (2017)

SB PROP @ ARL $ARLP009
ARLP009 Propagation de K7RA

ZCZC AP09
QST de W1AW  
Propagation Forecast Bulletin 9  ARLP009
From Tad Cook, K7RA
Seattle, WA  March 3, 2017
To all radio amateurs 

SB PROP ARL ARLP009
ARLP009 Propagation de K7RA

On March 2 at 2353 UTC the Australian Space Forecast Centre issued a
geomagnetic disturbance warning for March 3:

"The Earth is currently under the influence of a high speed solar
wind stream from a recurrent coronal hole. On 3 March geomagnetic
activity is expected to reach active levels. Isolated minor storm
periods are also possible."

This reporting week (February 23 through March 1, 2017) sunspot and
solar flux averages rose while geomagnetic indices remained about
the same, compared to the previous seven days. Average daily sunspot
numbers increased from 19.1 to 34.1, and average daily solar flux
went from 78.5 to 81.3.

Average planetary A index barely changed from 11.3 to 13.1, and
average mid-latitude A index (measured in Virginia) went from 9 to
8.7. The numbers went in opposite directions, but were each barely
changed.

Predicted solar flux is 79 on March 3, 78 on March 4-5, 77 on March
6-7, 76 on March 8, 75 on March 9-14, then 74, 75, 77, 79, and 80 on
March 15-19, 82 on March 20-23, 80 on March 24-25, 79 on March 26,
77 on March 27-28, 79 on March 29-31, 75 on April 1, 72 on April
2-3, 73 and 74 on April 4-5, 75 on April 6-10, and 74, 75 and 77 on
April 11-13.

Predicted planetary A index is 22, 14, 10 and 8 on March 3-6, 5 on
March 7-8, 8 on March 9, 5 on March 10-14 then 10, 20, 15, 10 and 8
on March 15-19, then 5, 8, 10, 15, and 8 on March 20-24, 5 on March
25-26, then 12, 25, 20, 15 and 8 on March 27-31, 5 on April 1-10,
and 10, 20, 15 and 10 on April 11-14.

F.K. Janda, OK1HH sent this forecast:

"Geomagnetic activity forecast for the period March 3-28, 2017

"Geomagnetic field will be:
Quiet on March 8-9, 12, 14, 26
Mostly quiet on March 10-11, 13, 15, 25
Quiet to unsettled March 7, 20-22, 24
Quiet to active on March 3-4, 6, 16, 18-19, 23, 27
Active to disturbed on March 5, 17, 28

"Amplifications of the solar wind from coronal holes are expected on
March 3-5, (6-8, 20-22,) 23-26.

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

We've been tracking a 3-month moving average of sunspot numbers for
several years now. The peak was centered on February and March 2014,
when the 3-month averages were 146.4 and 148.2. The average centered
on the end of 2014 was 107.8, and a year later was 55.4. At the end
of last year the average was 21, and the average centered on January
2017 was 20.6. The cycle will probably reach minimum in 2020.

Jon Jones, N0JK of Eastern Kansas sent this 10 meter update:

"The G2 class geomagnetic storm may have helped north - south paths.
The TX5T Austral Islands DXpedition was loud on 28.027 MHz and in my
log with one call at 2045z March 2. This on my mobile station. I saw
aurora contacts spotted on 6 meters March 1 such as N8JX EN64 to
K9MU EN44 at 2038z."

"Good conditions continued on 10 meters this week.  10 open to
Pacific" - N4EK  March 2, 2118z.

Dr. Tamitha Skov issued this solar storm forecast video on February
23:

http://bit.ly/2mNFO5g

This weekend is the ARRL International DX SSB Contest. See
http://www.arrl.org/arrl-dx for details.

If you would like to make a comment or have a tip for our readers,
email the author at k7ra@arrl.net.

For more information concerning radio propagation, see the ARRL
Technical Information Service web page at,
http://arrl.org/propagation-of-rf-signals. For an explanation of
numbers used in this bulletin, see
http://arrl.org/the-sun-the-earth-the-ionosphere.

An archive of past propagation bulletins is at
http://arrl.org/w1aw-bulletins-archive-propagation. More good
information and tutorials on propagation are at http://k9la.us/.

Monthly propagation charts between four USA regions and twelve
overseas locations are at http://arrl.org/propagation.  Instructions
for starting or ending email distribution of ARRL bulletins are at
http://arrl.org/bulletins.

Sunspot numbers for February 23 through March 1, 2017 were 18, 27,
25, 35, 40, 39, and 55, with a mean of 34.1. 10.7 cm flux was 83.3,
82.1, 80, 79, 82.2, 81.6, and 80.8, with a mean of 81.3. Estimated
planetary A indices were 11, 20, 7, 2, 8, 8, and 36, with a mean of
13.1. Estimated mid-latitude A indices were 8, 15, 6, 0, 6, 5, and
21, with a mean of 8.7.
NNNN
/EX