SB PROP @ ARL $ARLP048
ARLP048 Propagation de K7RA
ZCZC AP48
QST de W1AW
Propagation Forecast Bulletin 48 ARLP048
From Tad Cook, K7RA
Seattle, WA December 8, 2017
To all radio amateurs
SB PROP ARL ARLP048
ARLP048 Propagation de K7RA
Solar activity declined slightly over the past week, another period
which saw multiple days (five) with no sunspots. We will see more
of these periods over the next 2 to 3 years as the sun progresses
toward solar minimum.
There was a geomagnetic storm peaking on December 5. In Alaska the
College A index reached 55, and peaked around the middle of the UTC
day with K index reaching 7 over two 3-hour readings.
Our reporting week (Thursday through Wednesday) November 30 through
December 6 compared to the previous seven days saw average daily
sunspot numbers decline from 9.9 to 3.4, and average daily solar
flux from 73.5 to 69.6.
Recent consecutive days with zero sunspots were October 8 to 14,
October 16 to 20, November 1 to 13, November 19 to 24, and December
1 to 5.
Observe periods around the last solar minimum with long consecutive
periods of no sunspots at
ftp://ftp.swpc.noaa.gov/pub/indices/old_indices/2007_DSD.txt ,
ftp://ftp.swpc.noaa.gov/pub/indices/old_indices/2008_DSD.txt ,
ftp://ftp.swpc.noaa.gov/pub/indices/old_indices/2009_DSD.txt , and
ftp://ftp.swpc.noaa.gov/pub/indices/old_indices/2010_DSD.txt .
Over the past two weeks average planetary A index increased from 6.7
to 11.6 while average mid-latitude A index went from 5 to 8.1.
Predicted solar flux is 68 on December 8 to 10, 70 on December 11 to
14, 75 on December 15 and 16, 74 on December 17, 73 on December 18
to 20, 74 on December 21 and 22, then 76, 74, 72, 73 and 72 on
December 23 to 27, 70 on December 28 through January 8, 72 on
January 9, 75 on January 10 to 12, 74 on January 13, 73 on January
14 to 16, then 74, 74, 76, 74 and 72 on January 17 to 21.
Predicted planetary A index is 8 on December 8, 5 on December 9 and
10, 12 on December 11 and 12, 8 on December 13, 5 on December 14 to
16, then 8, 25 and 10 on December 17 to 19, 8 on December 20 and 21,
5 on December 22 to 26, 10 and 8 on December 27 and 28, 5 on
December 29 and 30, then 32, 48, 18, 12 and 8 on December 31 through
January 4, 5 on January 5 and 6, then 12, 15, 12 and 8 on January 7
to 10, 5 on January 11 and 12, then 8, 25 and 10 on January 13 to
15, 8 on January 16 and 17, and 5 on January 18 to 21.
F. K. Janda, OK1HH sends us his geomagnetic activity forecast for
the period December 8 til January 3, 2018.
"Geomagnetic field will be:
Quiet on December 9, 17, 23 and 24
Mostly quiet on December 8, 10, 14 to 16, 22, 25, 30
Quiet to unsettled on December 11, 26, 28
Quiet to active December 12, 20 and 21, 27, 29, 31, January 2 and 3
Active to disturbed on December 13, 18 and 19, January 1
Amplifications of the solar wind from coronal holes are expected on
December 8 (to 11), 17 to 22, (24 and 25), 30 and 31
Remark:
- Parenthesis means lower probability of activity
enhancement."
A new sunspot group (AR2690) emerged on December 6 after a period of
no sunspots, but spaceweather.com reports that early on December 7
it is already fading.
This weekend is the ARRL 10 meter contest. There is a good chance
for sporadic-e propagation. See
http://www.arrl.org/10-meter .
Tamitha Skov released this new video on December 7:
https://www.youtube.com/watch?v=sgQtC0EOIHIFor 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 November 30 through December 6, 2017 were 11, 0,
0, 0, 0, 0, and 13, with a mean of 3.4. 10.7 cm flux was 71.7, 70.2,
71.5, 69, 68.4, 67.9, and 68.3, with a mean of 69.6. Estimated
planetary A indices were 11, 8, 4, 2, 11, 29, and 16, with a mean of
11.6. Estimated mid-latitude A indices were 9, 5, 2, 1, 6, 21, and
13, with a mean of 8.1.
NNNN
/EX
