Propagation Update – January 5, 2018

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QST de W1AW
Propagation Forecast Bulletin 1  ARLP001
From Tad Cook, K7RA
Seattle, WA  January 5, 2018

To all radio amateurs

No sunspots appeared from December 27, 2017 until January 4, 2018. As Solar Cycle 24 declines to a minimum over the next two years we should see longer and more numerous periods of no sunspots. On January 4 the daily sunspot number was 13, indicating 3 sunspots in one sunspot group, although Spaceweather.com reported no sunspots on that day. The sunspot number for that day was reported by NOAA at ftp://ftp.swpc.noaa.gov/pub/indices/DSD.txt .

On January 4 Spaceweather.com reported a stream of solar wind should reach Earth on January 8, triggering some geomagnetic unrest, but nothing severe.

Over the recent reporting week (Thursday through Wednesday) the average daily sunspot number declined from 17.4 to 0, while average daily solar flux went from 74.6 to 70.4. Average daily planetary A index declined from 7.1 to 5.1, while average daily mid-latitude A index went from 5.7 to 3.4.

Predicted solar flux is 70 on January 5-6, 69 on January 7-8, 68 on January 9-11, 70 on January 12, 72 on January 13-24, 70 on January 25, 68 on January 26-31, 70 on February 1-8, and 72 on February 9-18.

Predicted planetary A index is 5 on January 5-6, then 8, 12 and 7 on January 7-9, 5 on January 10-12, then 22, 16 and 6 on January 13-15, 5 on January 16-19, then 12, 10, 8 and 6 on January 20-23, 5 on January 24-26, then 6, 25, 15 and 8 on January 27-30, 5 on January 31 through February 2, then 10, 12 and 6 on February 3-5, 5 on February 6-8, then 22, 16 and 6 on February 9-11, 5 on February 12-15, then 12, 10 and 8 on February 16-18.

Geomagnetic activity forecast for the period January 5-January 31, 2018 from F.K. Janda, OK1HH:

“Geomagnetic field will be:

  • Quiet on January 5, 11, 17-19, 31
  • Mostly quiet on January 6, 10, 30
  • Quiet to unsettled on January 12, 15-16, 23-26
  • Quiet to active on January 7, 20, 22, 27-29
  • Active to disturbed on January 8-9, 13-14, 21

“Amplifications of the solar wind from coronal holes are expected on January (6-8,) 10-12, (13,) 19-20, (21-22, 28-31).

“Remark: – Parenthesis means lower probability of activity enhancement.”

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 December 28, 2017 to January 3, 2018 were 0, 0, 0, 0, 0, 0, and 0, with a mean of 0. 10.7 cm flux was 71.1, 71.5, 70.4, 70.7, 69.1, 69.5, and 70.7, with a mean of 70.4. Estimated planetary A indices were 5, 4, 3, 4, 11, 5, and 4, with a mean of 5.1. Estimated mid-latitude A indices were 2, 3, 2, 2, 8, 4, and 3, with a mean of 3.4.

NNNN

/EX

ARRL is the national association for Amateur Radio in the US. Founded in 1914 by Hiram Percy Maxim as The American Radio Relay League, ARRL is a noncommercial organization of radio amateurs.

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