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ARRL Propagation Bulletin ARLP005 (2011)

ARLP005 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 5  ARLP005
From Tad Cook, K7RA
Seattle, WA  February 4, 2011
To all radio amateurs 

ARLP005 Propagation de K7RA

The past week had one zero sunspot day, Thursday, January 27.
Activity came right back, but the average daily sunspot number for
the week fell over 12 points to 20.1, and average daily solar flux
declined 2.7 points to 80.8.  After the sunspot numbers of 21, 22
and 22 on Monday, Tuesday and Wednesday, the sunspot number rose to
32 on Thursday, February 3.

Predicted solar flux values for the next week were below the average
for the previous seven days when reported on Thursday in the ARRL
Letter, but the forecast has improved since then.  Solar flux values
forecast by NOAA/USAF are 80 on February 4-8, 78 on February 9-10,
then 80, 80, 82, 81, 81, 82 and 88 on February 11-17.

Predicted A index on February 4-5 is 10 and 8, followed by 5 on
February 6-28.

Geophysical Institute Prague sees unsettled to active conditions for
today, February 4, unsettled February 5, quiet on February 6-8,
quiet to unsettled February 9, and unsettled conditions return on
February 10.

On Friday the STEREO craft are now very, very close to perfect
alignment for 100% coverage of the Sun.  I checked just now at 1430
UTC on February 4, and STEREO has achieved 99.899% coverage, the
missing sector now a tiny slit near the 180 degree meridian.  See it

By 2300 UTC on February 5 STEREO coverage should be 99.917%, and it
should reach 100% coverage shortly after 0926 UTC on Sunday,
February 6.  This is when the STEREO satellites begin their move
into the position where the gap closes on our Sun's far side, and
begins to open on the Earth side.  Images from the NASA Solar
Dynamics Observatory will begin to fill the new gap along the Sun's
zero degree meridian, the side facing us.  See the SDO page at for almost-live images.  They have a nice
gallery of recent images at

We have some new 3-month moving averages for sunspot numbers, and
this solar cycle appears stalled, although numbers are much higher
than a year ago, and are back up to the numbers seen on the downside
of cycle 23 during late 2005 and early 2006.

Our 3-month moving average takes the sum of all sunspot numbers for
three calendar months, divides the total by number of days, and
reports it as for the center month.  The next month's average drops
the oldest month and adds data from a new month.  So the latest
moving average is centered on December 2010, and takes the
arithmetic average of all the sunspot numbers over the 92 days from
November 1 through January 31. The total was 2,765 and the average
centered on December, 2010 was 30.1.

Here are the moving averages for the last four years, starting with
the numbers centered on January 2007. 2007 averages were 22.7, 18.5,
11.2, 12.2, 15.8, 18.7, 15.4, 10.2, 5.4, 3, 6.9, and 8.1.

For 2008 3-month moving averages were 8.5, 8.4, 8.4, 8.9, 5, 3.7, 2,
1.1, 2.5, 4.5, 4.4, and 3.6.

The 2009 averages were 2.2, 2, 1.5, 2, 4, 5.2, 4, 4, 4.6, 7.1, 10.2
and 15.

The 2010 averages were 22.4, 25.7, 22.3, 18.5, 16.4, 20.4, 23.2,
28.9, 33, 35.6, 31 and 30.1.

I believe it was 20 years ago this week, early February 1991, when I
took over writing this bulletin (without realizing it at first) from
Ed Tilton, W1HDQ who had written it for so many years that I've
found no one who recalls when it started.  I remember copying his
bulletin as a 13-14 year old on CW in 1966 from W1AW.

The propagation bulletin came out on Sunday, January 7 or February
3, saying that W1HDQ was ill, and there would be no propagation
bulletin from W1AW that week. Until then I had my 20 meter Yagi left
pointed toward 81 degrees (short path from me to W1AW) and my Drake
TR7 left on the 20-meter W1AW RTTY bulletin frequency.  I copied
ARRL bulletins unattended on FEC AMTOR (a serial mode with
redundancy and parity bits) and after cleaning them up, I would put
them out on the packet radio network via VHF. At that time the
coast-to-coast packet network was not well connected, and it would
often take several days for ARRL bulletins to reach the West Coast.
I had been doing the same thing with the VK2SG RTTY DX Bulletin.

Around the time Ed's illness was announced I noticed a dramatic rise
in solar indices.  The daily solar flux I copied from WWV on January
24-31, 1991 was 214, 267, 283, 303, 327, 353, 353 and 357.  Solar
cycle 22 was declining, and by the way, I cannot find any evidence
that there have been solar flux values anywhere near this high at
any time in the past 20 years. I thought it was a shame that the
ARRL wasn't reporting this in a bulletin, so I called ARRL
headquarters to see if the propagation bulletin would be returning
the following week.  The person I talked to said he didn't think so.
Then I called Ed Tilton at his home in Florida.

Ed's wife answered my call, and said he was too ill to speak with me
on the phone.  She asked why I was calling, and when I told her, she
said, "What are the numbers?"  When I told her the solar flux was
above 350 she quickly said, "Oh, he'll want to hear this!"  After a
long silence Ed's voice was on the line.  He was thrilled by the
news of the solar activity, but said he didn't know when he would be
able to write the next bulletin.

I called ARRL headquarters again, and told the person I had spoken
with that something HAD to be done, because this news was just too
big.  Maybe I could give him the information, and someone at
headquarters could write an interim propagation bulletin until Ed
recovered.  The person I spoke with said he had no idea who would do
this, so I volunteered that I was familiar with Ed's style because I
had been copying the bulletin and editing out errors for
redistribution via the packet network.

I was asked to write something up and email it in.  Yes, I had email
back in 1991, actually since the 1980s, due to the generosity of
WA6SWR, who gave me an email account and Usenet access so I could
read and post to  It was a UNIX shell
account at a company he owned.  Remember, this was just a few weeks
before Tim Berners-Lee released the first web browser and HTML
editor, so there was no worldwide web.

They liked the first bulletin, and asked if I could write another
the following week.  I never intended to replace Ed or even thought
I was qualified, and unfortunately Ed never recovered enough to
write another bulletin, and passed away over six years later.  Soon
I changed the release to Friday instead of Sunday evening, so we
could report propagation news just before each weekend.

Hard to believe it has been 20 years, but one week rolls into the
next, and time flies.  I've learned a little about propagation since
then, mostly from a helpful pool of patient, generous and
knowledgeable readers.

David Moore, who is not a ham, sent a press release from the
National Science Foundation about a new large-scale space weather
model.  Read about it at and see the
hi-res image at Also see the web page for
the Center for Integrated Space Weather Modeling at

Tamas Holman, HA5PT (see for photos) in
Budapest sent in this interesting report:

"In the morning of January 30 I was chasing DX on 17m and heard
UT7UJ calling CQ. Though Ukraine is not DX from Budapest I still
needed Ukraine confirmation on 17m and VE7CC DX cluster reported he
is LoTW member so I called right away. Dim hardly copied my 100W and
after the fourth attempt he was still asking QRZs. Because his
signal came to me on multiple paths with echoes I routinely switched
my SteppIR antenna direction to LP and suddenly his weak signals
became strong and we both got into our logs with 599. After our QSO
I recorded his CQ changing my antenna direction in the middle, the
first half is LP and the second SP direction. Looking at the audio
signals even the delay between the two paths can easily be measured
and it shows that the 0.13 sec was just needed to cover the 39,000
km distance through long path. Though when I called Dim I did not
want to make a long DX contact it turned out that I reached my ODX
QSO in my life."

ODX means his best long distance QSO.

Jeff Hartley, N8II of Shepherdstown, West Virginia reported on
February 1, "Low band conditions were fairly good over the past few
days. I didn't take part in the CQWW 160 contest. The high bands
have really been poor with very marginal western EU only on Sunday
the January 30; January 29 was a bit better. Taking a look at the
ARRL predictions for January, they are overly optimistic on MUF. We
have had very few openings to the west coast on 10 meters, charts
show about 3-1/2 hours starting 1730Z. Even South America which
shows an even longer opening is not present most days on 10 meters.
I think we all had expected better openings on 15 and 10 meters by
now. We had some really nice 10 meter openings February 2010 and
October 2010, but December and January have been pretty poor."

If you would like to make a comment or have a tip for our readers,
email the author at,

For more information concerning radio propagation, see the ARRL
Technical Information Service web page at For an explanation of the
numbers used in this bulletin, see An archive of past
propagation bulletins is at  Find more good
information and tutorials on propagation at

Monthly propagation charts between four USA regions and twelve
overseas locations are at

Instructions for starting or ending email distribution of ARRL
bulletins are at

Sunspot numbers for January 27 through February 2 were 0, 27, 27,
22, 21, 22, and 22, with a mean of 20.1. 10.7 cm flux was 80.5,
80.6, 81.4, 82.6, 81.3, 79.9 and 79.2 with a mean of 80.8. Estimated
planetary A indices were 3, 4, 4, 1, 5, 8 and 5 with a mean of 4.3.
Estimated mid-latitude A indices were 2, 4, 3, 2, 4, 7 and 5 with a
mean of 3.9.


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