SB PROP @ ARL $ARLP017
ARLP017 Propagation de
K7RA
ZCZC AP17
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:
From the same source, multiple detailed images per day of the
Sun
viewed at different wavelengths:
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:
If you would like to make a comment or have a tip for our
readers,
email the author at, k7ra@arrl.net
.
For more information
concerning radio propagation, see the ARRL
Technical Information Service web page 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
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 bat http://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.
NNNN
/EX
