SB PROP @ ARL $ARLP021
ARLP021 Propagation de K7RA
ZCZC AP21
QST de W1AW
Propagation Forecast Bulletin 21 ARLP021
From Tad Cook, K7RA
Seattle, WA May 22, 2015
To all radio amateurs
SB PROP ARL ARLP021
ARLP021 Propagation de K7RA
Sunspot numbers drifted below 100 over the past week (May 14 to 20),
and so the average daily sunspot number declined from 146.9 over the
previous seven days to 92.1 in the recent period. Average daily
solar flux dropped from 156.3 to 123.3.
You can see the decline in solar flux in addition to the decline in
predicted numbers by downloading the spreadsheet at
http://bit.ly/1KQGbRm which shows us the daily readings and the
shifting 45-day predictions from NOAA/USAF.
From that spreadsheet you can see that the predicted solar flux is
100 on May 22 and 23, 95 on May 24 to 28, 105 on May 29 and 30, 110
on May 31, 115 on June 1, 120 on June 2 and 3, 125 on June 4, 130 on
June 5 and 6, 120 on June 7 to 12, 110, 115, 105 and 95 on June 13
to 16, 90 on June 17 to 19, 95 on June 20, and 105 on June 21 to 26.
This value peaks again at 130 on July 2. ARRL Field Day is June 27
and 28, 2015 when predicted solar flux is 110 and 115, and predicted
planetary A index is 5.
Predicted planetary A index is 5 on May 22 to 24, 8 on May 25 and
26, 5 on May 27 and 28, 8 on May 29 and 30, 5 on May 31 to June 1,
15 and 10 on June 2 and 3, 5 on June 4 to 6, 12 on June 7, 25 on
June 8 and 9, 12 on June 10, 5 on June 11 and 12, then 8, 15 and 12
on June 13 to 15, and 5 on June 16 to 24. You can see these
predicted values and more, going out 45 days, by downloading the
spreadsheet at http://bit.ly/1IBXtnG .
OK1HH predicts geomagnetic activity will be quiet on May 22 and 23,
mostly quiet May 24, quiet to active May 25, quiet May 26 and 27,
quiet to unsettled May 28 and 29, mostly quiet May 30, quiet to
unsettled May 31, mostly quiet June 1, active to disturbed June 2,
quiet to active June 3, mostly quiet June 4 and 5, quiet to
unsettled June 6, quiet to active June 7 to 9, disturbed June 10 and
11, mostly quiet June 12, quiet June 13, quiet to active June 14,
active to disturbed June 15, quiet to active June 16, and quiet on
June 17.
OK1HH says the reliability of his predictions are reduced (although
I don't know why) and that he sees a possible increase in solar wind
on May 22 and 23, May 30, June 2 and 3, June 8 and 9 and June 12.
He puts parenthesis around dates he is particularly uncertain about,
and he has those around May 22 and 23 for both the quiet conditions
prediction and the increase in solar wind. The two seem mutually
exclusive to me, but since May 22 and 23 is today and tomorrow, we
should know soon enough. He also has parens around the increase in
solar wind for June 8 and 9.
Jon Jones, N0JK of Kansas shares this news about events on May 18:
"An unexpected aurora event occurred May 18. Around 2245z aurora
allowed stations in Minnesota, North Dakota, Illinois, Iowa,
Michigan and southern Canada to make 6 meter contacts. I heard K9KU
in Wisconsin and KC0CF in Iowa on 6 meter aurora in Kansas. The
aurora was due to unsettled solar wind which sparked a G2-class
geomagnetic storm."
For more information concerning radio propagation, see the ARRL
Technical Information Service at
http://arrl.org/propagation-of-rf-signals. For an explanation of
the 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/.
Archives of the NOAA/USAF daily 45 day forecast for solar flux and
planetary A index are in downloadable spreadsheet format at
http://bit.ly/1IBXtnG and http://bit.ly/1KQGbRm .
Click on "Download this file" to download the archive and ignore the
security warning about the file format.
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 May 14 through 20 were 126, 113, 103, 75, 83,
84, and 61, with a mean of 92.1. 10.7 cm flux was 145.1, 136.5,
131, 119.6, 115, 110.3, and 105.6, with a mean of 123.3. Estimated
planetary A indices were 10, 8, 6, 6, 16, 17, and 7, with a mean of
10. Estimated mid-latitude A indices were 9, 7, 7, 6, 15, 14, and
10, with a mean of 9.7.
NNNN
/EX
