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ARRL Propagation Bulletin ARLP039 (2012)

ARLP039 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 39  ARLP039
From Tad Cook, K7RA
Seattle, WA  September 28, 2012
To all radio amateurs 

ARLP039 Propagation de K7RA

Average daily sunspot numbers rose this week from 56 to 81.3, and
average daily solar flux increased from 101.4 to 129.7. As reported
in the ARRL Letter on Thursday, September 27, the increase was
expected to continue over the next few days, with solar flux peaking
at 150 on September 28-29, but what a difference a single day makes.

You can see the radical change in forecasts by going to and selecting
the September 26 prediction, then compare it to the September 27
prediction.  Instead of a solar flux on September 28 to October 1 of
150, 150, 145 and 145, the latest prediction for those days is 130,
130, 125 and 125. Each day shows a 20 point lower solar flux than
the earlier prediction.

So as it is now, from the September 27 prediction, we see solar flux
of 130 on September 28-29, 125 on September 30 through October 2,
120 on October 3-4, 130 on October 5, 125 on October 6-7, 120 on
October 8, 115 on October 9-10, 120 on October 11, 115 on October
12-13, and 120 on October 14-15. It is then expected to rise to a
peak of 150 on October 20 and 150 again on October 25-26, with the
average solar flux on October 21-24 around 141.

The average planetary A index declined from 7.4 last week (September
13-19) to 4.3 this week (September 20-26). The predicted planetary A
index values are 5 on every day through October 4, 8 on October 5, 5
on October 6-11, then 10 and 12 on October 12-13, and 5 on October
14-16, followed by 10 on October 17, 8 on October 18-20, and 5 on
October 21-25.

As always, we get a different perspective from the Czech Propagation
Interest Group and Petr Kolman, OK1MGW.  They see quiet to unsettled
geomagnetic conditions on September 28-29, quiet to active on
September 30 and October 1, active to disturbed on October 2, quiet
to active on October 3, quiet to unsettled October 4-5, mostly quiet
October 6-8, then quiet to unsettled October 9-12, mostly quiet
October 13-14, quiet to unsettled October 15, and quiet to active on
October 16-17.

John Parnell, K7HV has enjoyed working DX with low power, and then
documenting each new country worked on video, for what he refers to
as YouTube DXCC. Check out his videos at John also
reports from K7SS some great conditions on 10 meters last weekend
(September 22-23). Check John's listing at

We also heard of great 12 meter conditions last weekend from Chris
Callicott, G4DJJ of Northumberland in England. Chris reports:
"Between 1810-1850 UTC on September 22 I worked 15 stations across
IL, IN, MN, OH and WI. On September 23 from 1600-1620 UTC the band
opened from UK to central and SW USA, giving easy SSB QSOs with 35
stations in AZ, CA, NV, WA, IL, IN, OH, MI, WI, MN, and Mexico. All
loaded up to LoTW of course!"

A little solar activity helps, and of course we have transitioned to
Fall conditions, which makes a big difference. The Autumnal Equinox
was last weekend on September 22 at 1449 UTC.

Angel Santana-Diaz, WP3GW of Trujillo Alto, Puerto Rico reports, "I
suppose you had a big report on 10 meters this weekend! Saturday
September 22 in the afternoon was really busy on 10. Got to work
around 1534 UTC V5/DL3ZAD and at 1556 UTC VP9LP. Later at 1951 and
2001 UTC 7Z1TT, EA9BW and EA7QC, who told me it was around 10pm his
local time. The band was teaming with life! Then on Monday, got to
work JX9JKA on 12m at 1915 UTC, which is a new DXCC entity for me.
On other bands worked ZB2B, T77NM, 8P6CF and OX3KQ. And the bands
still are interesting, hope they are great for the CQ WW SSB."

John Kelley, K4WY of Fairfax Station, Virginia sent a tip about an
article claiming that we actually reached a sunspot cycle peak last
year, but that was just for the Sun's northern hemisphere.  The peak
for the southern hemisphere may not occur until 2014.  Although the
article talks about the disconnect between the two hemispheres
suggesting a grand minima in our future, note the comment from
Michael Proctor, a solar physicist at the University of Cambridge,
who is not convinced that this will happen. "This present cycle is
similar to the weak one that ended in 1913, and that was followed by
a strong cycle," he says.

Read the article at,

John Campbell, K4NFE of Huntsville, Alabama also gave us a tip about
this article.

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 September 20 through 26 were 68, 74, 46, 57, 90,
121, and 113, with a mean of 81.3. 10.7 cm flux was 117.4, 116.9,
124.5, 133.6, 136.6, 139.8, and 139.2, with a mean of 129.7.
Estimated planetary A indices were 9, 5, 4, 2, 2, 2, and 6, with a
mean of 4.3. Estimated mid-latitude A indices were 10, 5, 3, 1, 2,
2, and 6, with a mean of 4.1.


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