ARRL

Secure Site Login

ARRL Propagation Bulletin ARLP027 (2017)

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