ARRL Propagation Bulletin ARLP042 (2013)

ARLP042 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 42  ARLP042
From Tad Cook, K7RA
Seattle, WA  October 18, 2013
To all radio amateurs 

ARLP042 Propagation de K7RA

Recent solar activity took a healthy jump this week, with the
average daily sunspot number increasing nearly 48 points to 126.9, a
positive change of 60 percent compared to the previous week. Average
daily solar flux was up 16.4 points to 126.5.

The daily sunspot number rose to 148 on October 15, then 166 on
October 17, the highest it's been since May 15-17 when it was 186,
212 and 198.

The average planetary A index was unchanged at 8.1. The high
latitude college A index indicated active geomagnetic conditions on
October 14-15, when it was 31 and 27.

The latest prediction shows solar flux at 135, 130 and 120 on
October 18-20, 115 on October 21-23, 110 on October 24-25, 100 on
October 26-29, 105 on October 30-31, 100 on November 1-2, 110 on
November 3-4, 115 on November 5, 120 on November 6-7, and 125 on
November 8-12.

The predicted planetary A index is 8 on October 18, 5 on October
19-20, 12 and 10 on October 21-22, 5 on October 23 through November
10, 12 on November 11, 5 on November 12-16 and 8 on November 17-19.

F.K. Janda, OK1HH sent his geomagnetic forecast for this week, and
it predicts quiet to unsettled conditions October 18, quiet on
October 19-20, mostly quiet October 21, quiet to unsettled October
22, quiet October 23-24, mostly quiet October 25-26, quiet to
unsettled October 27, quiet to active October 28-29, quiet October
30 through November 3, quiet to unsettled November 4, quiet to
active November 5, quiet to active November 6, mostly quiet November
7-8, and quiet to unsettled November 9.

Two weeks ago we offered links to spreadsheets I've been maintaining
which show the recent history of the NOAA/USAF 45 day forecast for
solar flux and planetary A index. The recent forecasts are online at

You can download my solar flux spreadsheet at and planetary A index sheet at . No password needed this time. These can
be interesting for checking recent forecast trends, such as when
projections for future activity trend up or down, and you can see
this clearly when you peruse the spreadsheet. Note how there were
projections over the last 3-7 weeks showing predicted solar flux
values for some periods at 90 or 95. The most recent predictions
show a stronger outlook.

Randy Crews, W7TJ sent this report on October 17: "Last weekend 10
and 12 meters were the best I have heard all Fall. The Solar Flux
rising out of the mid nineties doldrums was a BIG help. Looks as if
we are going to enter a period of reasonably high solar activity,
(Solar flux at 100-125) coupled with a long period of quiet
geomagnetic conditions and low solar wind, in addition to the
seasonal improvements we have in October. The aforementioned coupled
with all the DXpedition activity and the upcoming CQ WW SSB Contest,
the bands should be hot!  I am making the most of 10 and 12 meter
propagation, as I don't think propagation on those bands will be
there a year from now.  Our solar flux will be pressed to average
over 117 this Month. A year ago October's average was 123. I like
the old Farm quote: 'Make Hay While The Sun Shines'."

That's right, Randy, flux values were a little stronger a year ago.
In Propagation Forecast Bulletins ARLP040 to 044 from 2012, the
weekly averages of solar flux were 128.7, 104.9, 129.2, 143.9 and
116.9. It is interesting though that sunspot numbers are higher now.
The average sunspot number over this past week was 126.9, but
sunspot number averages from those same 2012 bulletins referenced
above for solar flux were 73, 51.7, 97, 95.3 and 58.4.

Jon Jones, N0JK, the QST columnist who writes "The World Above 50
MHz" wrote on October 11 from EM28 in Kansas in a message titled,
"F2 on 6 meters October 9."

"I heard LW3EX on 50.100 MHz CW weak via afternoon F2/TEP on Oct. 9
about 2040 UTC. Walt and other Argentinean stations were much louder
about 3 grids south of me (EM28) in Oklahoma (EM25) and Texas.

"The geomagnetic field was active at the time."

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numbers used in this bulletin, see An archive of past
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Sunspot numbers for October 10 through 16 were 138, 115, 106, 125,
136, 148, and 120, with a mean of 126.9. 10.7 cm flux was 120.7,
129, 127.9, 129.3, 125, 125.3, and 128.1, with a mean of 126.5.
Estimated planetary A indices were 9, 5, 5, 2, 13, 14, and 9, with a
mean of 8.1. Estimated mid-latitude A indices were 7, 3, 3, 2, 10,
14, and 9, with a mean of 6.9.