Propagation Forecast Bulletin #39 de K7RA:
W1AW Bulletin via the ARRL
September 30, 2011
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Propagation Forecast Bulletin #39 de K7RA:
QST de W1AW
Propagation Forecast Bulletin 39 ARLP039
?From Tad Cook, K7RA
Seattle, WA September 30, 2011
To all radio amateurs
SB PROP ARL ARLP039
ARLP039 Propagation de K7RA
Our Sun was very active over the past week, with average solar flux
rising nearly 12 points to 155.5. Average daily sunspot numbers
however dropped nearly 41 points to 96.1. This implies fewer but
more intense sunspots.
A huge sunspot group numbered 1302 emerged on September 22, and this
was the source of a coronal mass ejection which triggered an immense
geomagnetic storm. The planetary A index peaked at 67 on September
26, followed by 30 the next day and 24 on September 28. The
planetary K index reached 8 for two of the three-hour reporting
periods on September 26, indicating an intense geomagnetic storm,
and with aurora observed in many places, including Maine,
Massachusetts, Michigan, Minnesota, New York, North Dakota and South
On September 22 there was a major X1.4 class solar flare at 1100
UTC, with a large CME, but this was when sunspot 1302 was just
coming over the horizon, so it wasn't Earth directed.
On September 24 sunspot group 1302 produced a larger X1.9 flare, and
today the group is just past the point where it is directly facing
Earth, but still in the middle of the visible solar disc. It could
still produce more flares.
Sunspot group area is measured in millionths of a solar hemisphere,
and for sunspot group 1302 the measure for September 22-28 was 480,
840, 1300, 980, 950, 980 and 1070. The combined area for all visible
sunspot groups peaked at 1930 on September 24. This is the largest
measure of sunspot area since January 15-16, 2005 in Cycle 23, when
the numbers were 1980 and 1960. The time period between those big
numbers is six years, 8 months and 9 days.
Other big numbers over the past decade for total sunspot area were
2420 on July 21, 2004, 5690 on October 30, 2003 (sunspot number was
293 that day), and 3940 and 3160 on March 29 and September 24, 2001.
The sunspot number on both those days in 2001 was 315.
Another big number this week emerged on September 24 when the solar
flux was 190.4. The number hasn't been this high since November 2,
2003 when it was also 190.4. The days prior to that beginning on
October 25, 2003 had solar flux values of 221.5, 298.3, 257.2,
274.4, 291.7, 271.4, 248.9, and 210.4. This was probably the last
big blast of solar activity for Cycle 23, as nothing since then
comes anywhere near that level.
Currently the latest forecast - which is actually from Thursday,
September 29 - from NOAA/USAF has solar flux at 140 for September 30
through October 3, then 135, 130, 135 and 140 on October 4-7, then
145 on October 8-10 and 140 on October 11-17.
Predicted planetary A index is 12 and 10 on September 30 through
October 1, then 5 on October 2-7, then 8, 15, 12 and 8 on October
8-11, and 5 on October 12-21.
Geophysical Institute Prague expects unsettled conditions on
September 30, quiet to unsettled October 1-3, and quiet October 4-6.
A note from Tom Jerardi, K3CXW corrects our reference to the
Autumnal Equinox in the northern hemisphere, as it means equal day
and night, which is independent of hemisphere.
Fred Honnold, KH7Y is in Ocean View, Hawaii, on the southwest part
of the Big Island. Fred reported that on Thursday night, September
23 he worked three new countries on 6 meters, and that "Six is
cooking." He has worked 56 countries on 6 meters since 2006. He
worked "BV2DQ at 0324z, PP5XX at 0404z, DU7/PA0HIP at 0455z who most
of the evening was 569, and LU5FF for an 11,000 KM QSO at 0512z,
plus FK8CP (loud) two hours and three VK4s, FP and CX. It all ended
After Fred worked PP5XX (in grid square GG55QW, 12541 KM from Fred),
PP5XX worked BV2DQ long path. BV2DQ was running 100 watts into a
Julio, NP3CW in San Juan, Puerto Rico reports that on September 23,
10 and 12 meters were open for many hours to Europe. In four hours
he worked 75 stations from Europe on 10 meters, and 4X4K in
Azerbaijan. He had 60 contacts with Europe and some North America on
12 meters, and he worked 40 JA stations in one hour on 12 meter CW.
On 6 meters he worked a number of stations across South America.
Don Keith, N4KC writes, "I've been licensed for 50 years this
year...since I was 13...but somehow always managed to be inactive
during sunspot maxima. I've really been anticipating this cycle, and
not so patiently, I admit.
"However, tonight between 0015 and 0110 GMT (September 23 CDST) made
the wait worthwhile. In about an hour, I worked 4W6A in East Timor,
JT1RF in Mongolia, and JH7PKU in Japan, all with good signals on 12
meters. I only run 100 watts and use a hexbeam on 12. SFI was
reported as 173. 12 is a totally new experience for me since it
wasn't even a ham band when I was active before and has been spotty
since 2005 when my interest was rekindled."
Don has a web site at
Scott Avery, WA6LIE of Salinas, California is also excited. On
September 25 he wrote, "WOW! The SFI up to 190 and solar activity is
on the rise! 10 meters today was like Field Day! Band was open to
Europe, Africa, VK/ZL etc! Could randomly spin the dial in the SSB
portion and find a signal. Reminds me of the late 80s when 10 was
open most of the time. Look forward to the MUF getting up to 50 MHz.
"Saw a DX spot, F2 from a station in San Diego to New Caledonia on 6
meters. Looks promising! Time for the Technicians to get in there
and work some DX!"
On September 25, a note from Nagoya: "This is JQ2UOZ (Name: 'Aki')
of Nagoya, Japan. The band conditions on 12 meters have been
"Using an output power of only 500 mw QRPp and a dipole antenna, I
was able to work FG5FR of Guadeloupe (Sep. 21) and YV1DIG of
Venezuela (Sep. 23) on 12 meter band CW. The area around the
Caribbean Sea is the most difficult area to work from Japan.
"In addition, using the same equipment, I was able to work K2ZJ of
the State of New York on 12 meter band CW (Sep. 23). Surprisingly,
according to an e-mail from him, he was using a very simple antenna,
that is, a double extended Zepp for 17 meter band!!"
The double extended Zepp is a dipole 1.28 wavelengths long, or about
66 feet on 17 meters, but apparently K2ZJ used his on 12 meters.
Peter Laws, N5UWY is net control on a local 10 meter net in Norman,
Oklahoma, and was surprised to hear Randy, KH6RC of Hawaii (actually
in the same Big Island village that KH7Y is in) check into his net
on September 22 at 0130z with a great signal, and everyone could
hear and work him. Peter was surprised, but with recent solar
activity, that report is not surprising. A check with W6ELprop shows
that path would probably be open until at least 0300z. But run the
same numbers again for July or August, and the results are much
different: no likely propagation over that path.
WP3GW is also giddy with joy over recent propagation. He worked the
CQ World Wide RTTY Contest, and says, "What a roll! Did 350 plus
contacts, something I have never made before on a digital contest!
This included 63 DXCC entities including 34 from Europe, plus 3 new
countries on RTTY including DXpedition OJ0X, UN1L and OD5HJ. Also my
friend Jose Rivera, KP4JRS, did 600 plus and Victor, NP4BM almost
900. Later learned about the 190 Solar Flux number! Even Europe came
strong on 10 meters as of 1315 UTC on Sunday."
Jon Jones, N0JK of Kansas is active on 6 meters, and reports "Had a
single hop F2 opening on 6M Sept 26 due to the geomagnetic storm
that day. From Kansas I worked 9Y4VU and HP3TA, both on CW around
2215 UTC. Heard HC1HC, NP4A and the HK6FRC/b. Also heard the OA4TT/b
FH16 on 50.077 MHz."
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
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. Find more good
information and tutorials on propagation at
Monthly propagation charts between four USA regions and twelve
overseas locations are at
istribution of ARRL
Sunspot numbers for September 22 through 28 were 86, 90, 88, 108,
103, 82, and 116, with a mean of 96.1. 10.7 cm flux was 150.8,
158.2, 190.4, 168.8, 148.2, 139, and 133.4, with a mean of 155.5.
Estimated planetary A indices were 3, 3, 4, 4, 67, 30, and 24, with
a mean of 19.3. Estimated mid-latitude A indices were 2, 2, 3, 4,
20, 22, and 13 with a mean of 9.4.
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