QST de W1AW  
Propagation Forecast Bulletin 33  ARLP033
>From Tad Cook, K7RA
Seattle, WA  August 18, 2017
To all radio amateurs 

SB PROP ARL ARLP033
ARLP033 Propagation de K7RA

Several readers pointed out those averages for the various
indicators we track were all wrong last week. Average daily sunspot
number was 12.1 instead of 5, although the rest of the text in the
bulletin was correct. Likewise, average daily solar flux was 73.2
instead of 71.

And average daily planetary A index was 11.3 instead of 5, and
mid-latitude A index was really 6.9 instead of 6.

The current (most recent) week, August 10-16 showed average sunspot
numbers at 15.3 and average solar flux at 72.

Predicted solar flux is 78 and 77 on August 18-19, 76 on August
20-24, 72 on August 25, 68 on August 26-28, 70 on August 29, 72 on
August 30 through September 8, 70 on September 9, 68 on September
10-24, 70 on September 25, and 72 on September 26 to October 1.

Predicted planetary A index is 24, 18, 16, 14 and 12 on August
18-22, 8 on August 23-24, 5 on August 25-29, then 12, 24, 18, and 14
on August 30 through September 2, 5 on September 3-7, 10 on
September 8, 8 on September 9-10, then 5, 10, 20, 25, 15, 12, 10, 8
and 6 on September 11-19, 5 on September 20-25, and 12, 24, 18, and
14 on September 26-29, then 5 on September 30 and October 1.

'Geomagnetic activity forecast for the period August 18-24, 2017:

'Quiet:       Aug 22-24
Unsettled:   Aug 20-22
Active:      Aug 18-19
Minor storm: Aug 18

'Geomagnetic activity summary: We expect an active minor storming
episode within the next 24 hours. Expect active conditions August
18-19. Friday (August 18), the K-index may reach 5 (minor storming
event). Saturday, August 19, we expect at most unsettled to active
conditions.

'The following two days August (20-21), we expect at most unsettled
conditions with one isolated active event.

'The rest of the forecast week (August 22-24), we expect quiet to
unsettled conditions.

'Tomas Bayer
RWC Prague
Institute of Geophysics of the Academy of Sciences of the Czech
Republic, Prague
Department of Geomagnetism
Budkov observatory (BDV)'

Solar eclipse mania: bit.ly/2tG6njO .

On Monday, don't miss the total solar eclipse and the related Solar
Eclipse QSO Party: hamsci.org/seqp .

If you would like to make a comment or have a tip for our readers,
email the author at [email protected].

For more information concerning radio propagation, see the ARRL
Technical Information Service web page at,
arrl.org/propagation-of-rf-signals. For an explanation of
numbers used in this bulletin, see
arrl.org/the-sun-the-earth-the-ionosphere.

An archive of past propagation bulletins is at
arrl.org/w1aw-bulletins-archive-propagation. More good
information and tutorials on propagation are at k9la.us/.

Monthly propagation charts between four USA regions and twelve
overseas locations are at arrl.org/propagation.

Instructions for starting or ending email distribution of ARRL
bulletins are at arrl.org/bulletins.

Sunspot numbers for August 10-16, 2017 were 11, 11, 11, 11, 12, 21,
and 30, with a mean of 15.3. 10.7 cm flux was 71, 69.8, 70.3, 68.2,
73, 74.2, and 77.3, with a mean of 72. Estimated planetary A indices
were 5, 7, 11, 7, 5, 4, and 6, with a mean of 6.4. Estimated
mid-latitude A indices were 7, 7, 12, 9, 5, 3, and 5, with a mean of
6.9.