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Propagation Forecast Bulletin #48 de K7RA:

from W1AW Bulletin via the ARRL on December 8, 2017
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Propagation Forecast Bulletin #48 de K7RA:

ZCZC AP48
QST de W1AW
Propagation Forecast Bulletin 48 ARLP048
>From Tad Cook, K7RA
Seattle, WA December 8, 2017
To all radio amateurs

SB PROP ARL ARLP048
ARLP048 Propagation de K7RA

Solar activity declined slightly over the past week, another period which saw multiple days (five) with no sunspots. We will see more of these periods over the next 2 to 3 years as the sun progresses toward solar minimum.

There was a geomagnetic storm peaking on December 5. In Alaska the College A index reached 55, and peaked around the middle of the UTC day with K index reaching 7 over two 3-hour readings.

Our reporting week (Thursday through Wednesday) November 30 through December 6 compared to the previous seven days saw average daily sunspot numbers decline from 9.9 to 3.4, and average daily solar flux from 73.5 to 69.6.

Recent consecutive days with zero sunspots were October 8 to 14, October 16 to 20, November 1 to 13, November 19 to 24, and December 1 to 5.

Observe periods around the last solar minimum with long consecutive periods of no sunspots at

ftp://ftp.swpc.noaa.gov/pub/indices/old_indices/2007_DSD.txt ,
ftp://ftp.swpc.noaa.gov/pub/indices/old_indices/2008_DSD.txt ,
ftp://ftp.swpc.noaa.gov/pub/indices/old_indices/2009_DSD.txt , and
ftp://ftp.swpc.noaa.gov/pub/indices/old_indices/2010_DSD.txt .

Over the past two weeks average planetary A index increased from 6.7 to 11.6 while average mid-latitude A index went from 5 to 8.1.

Predicted solar flux is 68 on December 8 to 10, 70 on December 11 to 14, 75 on December 15 and 16, 74 on December 17, 73 on December 18 to 20, 74 on December 21 and 22, then 76, 74, 72, 73 and 72 on December 23 to 27, 70 on December 28 through January 8, 72 on January 9, 75 on January 10 to 12, 74 on January 13, 73 on January 14 to 16, then 74, 74, 76, 74 and 72 on January 17 to 21.

Predicted planetary A index is 8 on December 8, 5 on December 9 and 10, 12 on December 11 and 12, 8 on December 13, 5 on December 14 to 16, then 8, 25 and 10 on December 17 to 19, 8 on December 20 and 21, 5 on December 22 to 26, 10 and 8 on December 27 and 28, 5 on December 29 and 30, then 32, 48, 18, 12 and 8 on December 31 through January 4, 5 on January 5 and 6, then 12, 15, 12 and 8 on January 7 to 10, 5 on January 11 and 12, then 8, 25 and 10 on January 13 to 15, 8 on January 16 and 17, and 5 on January 18 to 21.

F. K. Janda, OK1HH sends us his geomagnetic activity forecast for the period December 8 til January 3, 2018.

"Geomagnetic field will be:
Quiet on December 9, 17, 23 and 24
Mostly quiet on December 8, 10, 14 to 16, 22, 25, 30
Quiet to unsettled on December 11, 26, 28
Quiet to active December 12, 20 and 21, 27, 29, 31, January 2 and 3
Active to disturbed on December 13, 18 and 19, January 1

Amplifications of the solar wind from coronal holes are expected on December 8 (to 11), 17 to 22, (24 and 25), 30 and 31

Remark:
- Parenthesis means lower probability of activity enhancement."

A new sunspot group (AR2690) emerged on December 6 after a period of no sunspots, but spaceweather.com reports that early on December 7 it is already fading.

This weekend is the ARRL 10 meter contest. There is a good chance for sporadic-e propagation. See http://www.arrl.org/10-meter .

Tamitha Skov released this new video on December 7:

https://www.youtube.com/watch?v=sgQtC0EOIHI

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.

Sunspot numbers for November 30 through December 6, 2017 were 11, 0, 0, 0, 0, 0, and 13, with a mean of 3.4. 10.7 cm flux was 71.7, 70.2, 71.5, 69, 68.4, 67.9, and 68.3, with a mean of 69.6. Estimated planetary A indices were 11, 8, 4, 2, 11, 29, and 16, with a mean of 11.6. Estimated mid-latitude A indices were 9, 5, 2, 1, 6, 21, and 13, with a mean of 8.1.
NNNN
/EX

Source: W1AW Bulletin via the ARRL.

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