QST de W1AW  
Propagation Forecast Bulletin 17  ARLP017
>From Tad Cook, K7RA
Seattle, WA  April 27, 2018
To all radio amateurs 

SB PROP ARL ARLP017
ARLP017 Propagation de K7RA

Solar activity increased over the past week, with average daily
sunspot numbers up from 5.4 to 20 and average daily solar flux
rallying from 69.9 to 73.4. The previous week saw four days with no
sunspots, and the recent week had sunspots on every day. New sunspot
groups emerged on April 19 and 21.

Predicted solar flux is 69 on April 27-29, 68 on April 30 through
May 3, 70 on May 4-16, 75 on May 17-29, 70 on May 30 through June
10.

Predicted planetary A index is 12 on April 27, 5 on April 28 through
May 5, then 10, 15, 12, 10 and 8 on May 6-10, 5 on May 11-16, then
42, 12 and 8 on May 17-19, 5 on May 20-22, then 8 and 12 on May
23-24, 5 on May 25 through June 1, then 10, 15, 12, 10 and 8 on June
2-6, then 5 on June 7-10.

Geomagnetic activity forecast for the period April 27 to May 22,
2018 from F.K. Janda, OK1HH of the Czech Propagation Interest Group.

'Geomagnetic field will be:
Quiet on April 30
Mostly quiet on April 28, May 3, 14, 16, 21-22
Quiet to unsettled on April 27, 29, May 1, 4, 8, 11-13, 19-20
Quiet to active on May 2, 5, 9-10, 15, (18)
Active to disturbed on May 6-7, 17

'Solar wind will intensify on April (27-29), May (2,) 5-7, (8-11,)
17-18, (19-20).

'Remarks: 
- Parenthesis means lower probability of activity enhancement. 
- With regard to ongoing changes, current forecasts are less 
  reliable again.'

Interesting videos with general information on sunspots and solar
flares:

www.thesuntoday.org/the-sun/solar-activity/

>From the same source, multiple detailed images per day of the Sun
viewed at different wavelengths:

www.thesuntoday.org/the-sun-now/

Dr. Tamitha Skov will probably release a new space weather video
after this bulletin is sent to ARRL HQ for distribution. This is
probably a good place to check for her latest report:

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

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 bat arrl.org/bulletins.

Sunspot numbers for April 19 through 25, 2018 were 14, 14, 34, 20,
22, 19, and 17, with a mean of 20. 10.7 cm flux was 70.8, 73, 76.8,
75.7, 73.9, 72.9, and 70.8, with a mean of 73.4. Estimated planetary
A indices were 3, 47, 12, 5, 6, 5, and 5, with a mean of 11.9.
Estimated mid-latitude A indices were 2, 29, 10, 5, 6, 4, and 4,
with a mean of 8.6.