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K7RA's Solar Report

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Last update: Friday, 28-Apr-2017 06:57:21 GMT

SB PROP @ ARL $ARLP017
ARLP017 Propagation DE K7RA
QST DE W1AW
Propagation Bulletin 17 ARLP017 From Tad Cook, K7RA
Seattle, WA April 28 2017
To all radio amateurs

Each of the average solar and geomagnetic indices rose last week (April 20-26) over the previous seven days.

Average daily sunspot number rose from 8.6 to 35.7, and solar flux rose from 76.5 to 81.4.

Average daily planetary A index went from 8 to 26.4, and average daily mid-latitude A index from 6.3 to 18.4.

The day with the most geomagnetic activity was April 22 when the planetary A index was 54. One the same date, Alaska's College A index (nearFairbanks) was 86.

Predicted planetary A index is 8, 5 and 5 on April 28-30, then 14, 10, 8 and 10 on May 1-4, 15 on May 5-6, 8 on May 7-8, 5 on May 9-14, 8 and 15 on May 15-16, and then into a more active period at 30, 25, 45, 50 and 30 on May 17-21. Then 20 on May 22-24, then 15, 8, 5 and 20 on May 25-28, 10 on May 29-31, 15 on June 1-2, 8 on June 3-4, and 5 on June 5-9.

Predicted solar flux values are 79 on April 28-29, 78 on April 30 and May 1, 77 on May 2-4, 75 on May 5-14, 80 on May 15-18, 85 on May 19-24, 80 on May 25-28 and 75 on May 29 to June 10.

OK1HH sent us this geomagnetic activity forecast for the period April 28 til May 24, 2017.

"Geomagnetic field will be:Quiet on May 9-10, 12-13 Mostly quiet on April 30, May 7 Quiet to unsettled April 29, May 2, 4, 14, 21-24 Quiet to active on April 28, May 1, 3, 8, 11, 15-16, 19 Active to disturbed on May (5-6,) 17-18, 20

Amplifications of the solar wind from coronal holes are expected on April 28, May (1-5,) 6-8, (9-11,) 18-22

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

I thought I ran this last week, but apparently not:

https://www.youtube.com/watch?v'DJR7D9zTygao

These always seem to come out after the bulletin is posted.

You might want to check this for more up to date videos from Tamitha Skov:

https://www.youtube.com/user/SpWxfx/videos

Thanks to Don, N5DM for that tip.

For more information concerning radio propagation, see the ARRL Technical Information Service 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 April 20 through 26, 2017 were 26, 39, 29, 43, 41, 36, and 36, with a mean of 35.7. 10.7 cm flux was 80.7, 82.2, 83.6, 82.5, 80.2, 81.3, and 79.6, with a mean of 81.4. Estimated planetary A indices were 30, 19, 54, 41, 20, 12, and 9, with a mean of 26.4. Estimated mid-latitude A indices were 20, 11, 37, 24, 19, 10, and 8, with a mean of 18.4. NN


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