SB PROP @ ARL $ARLP027
ARLP027 Propagation de K7RA

ZCZC AP27
QST de W1AW
Propagation Forecast Bulletin 27 ARLP027

From Tad Cook, K7RA

Seattle, WA July 7, 2017
To all radio amateurs

SB PROP ARL ARLP027
ARLP027 Propagation de K7RA

At 0057 UTC on July 7 the Australian Space Forecast Centre issued a Geomagnetic
Disturbance Warning: "Expect an increase in geomagnetic activity late on UT day, 08 to 09 July due to influence of geoeffective coronal hole."

Our sun showed no sunspots on July 3 and 4, so average daily sunspot numbers dropped from 20.3 on June 22 to 28 to 8 during the current reporting week, June
29 through July 5. Average daily solar flux went from 73.6 to 71.7.

Average daily planetary A index went from 6.9 to 7.1 and average mid-latitude A
index went from 7.4 to 8.3, barely any change.

Predicted solar flux is 76 on July 7, 78 on July 8 to 13, 75 on July 14, 71 on July 15, 72 on July 16 to 19, 71 on July 20 to 27, 70 on July 28 through August
2, 71 on August 3 to 11, 72 on August 12 to 15 and 71 on August 16 to 20.

Predicted planetary A index is 5 on July 7, then 8, 25, 18 and 12 on July 8 to 11, then 8, 5, 13 and 11 on July 12 to 15, 5 on July 16 to 20, 11 on July 21 and 22, 5 on July 23 to 31, 7 on August 1 and 2, 5 on August 3 to 8, then 23, 13 and 11 on August 9 to 11, 5 on August 12 to 16, 11 on August 17 and 18 and 5
on August 19 and 20.



F. K. Janda, OK1HH of the Czech Propagation Interest Group sent this geomagnetic activity forecast for the period July 7 to August 3, 2017.

"Geomagnetic field will be:
Quiet on July 11, 18, 25 and 26, August 1
Mostly quiet on July 7, 17, 19 to 21, 24, 29 to 31
Quiet to unsettled July 9 and 10, 16, August 2 and 3
Quiet to active on July 8, 12 and 13, 15, 22 and 23, 27
Active to disturbed on July 14, 28

Amplifications of the solar wind from coronal holes are expected on July (8,) 9
to 12, 14 to 17, (18, 21,) 22 to 24, (25,) 30 and 31

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



Max White, M0VNG of Worcester, England sent this very interesting space weather
audio dispatch from the UK Met Office:

http://www.metoffice.gov.uk/learning/mostly-weather/episode11



Check this:

https://www.space.com/37330-solar-minimum-coronal-holes-space-junk.html



And finally, Dick Bingham, W7WKR who lives way off the grid, "1.2 miles up Company Creek Road" near Stehekin, Washington (check his QRZ.com listing) sent this off-topic but fascinating piece about an ancient computer.

http://wapo.st/2sU76Zx

I've heard about this artifact before, but never in such detail.



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 June 29 through July 5, 2017 were 12, 11, 11, 11, 0, 0, and
11, with a mean of 8. 10.7 cm flux was 71.8, 71.5, 70.7, 71.2, 71.7, 71.8, and 73, with a mean of 71.7. Estimated planetary A indices were 5, 4, 11, 18, 5, 4, and 3, with a mean of 7.1. Estimated mid-latitude A indices were 6, 4, 14, 20, 7, 5, and 2, with a mean of 8.3.

NNNN
/EX

)\/(ark

Always Mount a Scratch Monkey
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