SB PROP @ ARL $ARLP037
ARLP037 Propagation de K7RA
QST de W1AW
Propagation Forecast Bulletin 37 ARLP037
From Tad Cook, K7RA
Seattle, WA September 16, 2022
To all radio amateurs
SB PROP ARL ARLP037
ARLP037 Propagation de K7RA
Solar activity bounced back this reporting week, September 8-14,
when average daily sunspot numbers jumped from 68 to 92.7, and
average solar flux from 125.8 to 141.3.
Fewer CMEs and flares were evident, with average planetary A index
declining from 24.6 to 10.7, and middle latitude numbers from 17.4
New sunspot groups appeared, one on September 8, three on September
10, and one more on September 13. Total sunspot area (in millionths
of a solar disc) on September 12-14 rose from 370 to 870 to 1240,
the highest value in over a month.
The sunspot number was highest on September 10 at 122.
During this week two years ago, there were no sunspots at all, and
average daily solar flux was only 69.7, over 56 points lower than
this week, demonstrating the continued progress of Solar Cycle 25.
The latest (Thursday) forecast from space weather folks at Offut Air
Force Base shows predicted solar flux peaking at 150 on October 9,
but with flux over the next few days following this bulletin less
optimistic than the numbers in the bulletin preview in Thursday's
Predicted flux values on September 16-17 are 140 and 135, then 125
on September 18-19, 120 on September 20-29, 125 on September 30
through October 6, 130 on October 7-8, then 150, 148, 143 and 140 on
October 9-12, then 136, 130, 125 and 120 on October 13-16, 125 on
October 17-18, and 120 on October 19-26.
Predicted planetary A index shows moderate levels of geomagnetic
activity until October 1-2. The forecast is 15, 18 and 10 on
September 16-18, 5 on September 19-23, then 10 on September 24, 14
on September 25-27, 8 on September 28-29, then 22, 50, 30, 20 and 12
on September 30 through October 4, then 15, 12, 10, 8 and 5 on
October 5-9, then 10, 8, 5, 15, 20 and 12 on October 10-15, then 5
on October 16-19, then 12 and 10 on October 20-21, and 14 on October
The Autumnal Equinox is only a week away!
Nice solar video from last month:
Here is NOAA's latest forecast discussion:
Comments from F.K. Janda, OK1HH:
"Although the Sun was speckled a week ago, all areas were quiet and
overall, the Sun's activity was low. After that, activity began to
grow rapidly in the northern hemisphere.
"Sunspot group AR3098 grew larger and on September 11, a C6 class
flare was registered. The old area AR3088, which was active during
the last rotation of the Sun, returned in the southeast solar limb.
"Two solar wind shock waves hit our planet on September 14 at 0630
UTC and 2313 UTC. The second of them significantly expanded the
speed of the solar wind, started a disturbance of the Earth's
magnetic field and caused very uneven shortwave propagation
conditions, especially on routes leading through higher latitudes.
Auroral distortion of signals were observed when passing through
inhomogeneities in the auroral belt.
"Further similar disturbances can be expected on September 17th, a
calm after September 18th and a decrease in solar activity is
expected after September 20th."
The following is edited from an email from David Greer, N4KZ in
"With the Sun perking up from its long sleep, one of my favorite
bands, 12 meters, is also coming alive. I've worked FT8 DX on 12
meters from time to time for months, but things really came alive
for me from 1236-1356 UTC on September 14 when I worked 22 DX
stations back-to-back on SSB.
"I called CQ and was answered by a Dutch station and after that,
stations just kept calling and calling. I put 22 DX stations in my
log. Most were from Europe, but I also worked the Middle East and
Northwest Africa, 18 different DX entities all together.
"Some signals were quite strong, mostly because they ran high power
with beam antennas but one station was thrilled to make the trip
across the pond from Europe because, he said, 'he was running 100
watts to an indoor dipole in his apartment.'
"Some commented it was their first ever 12-meter QSO. I hear that
often from stations everywhere. Some say they didn't think anyone
ever used 12 meters. Since 2000, I have 12 meter WAS and confirmed
182 DX entities on 12 alone.
"I often call CQ on SSB when the band seems dead, only to have a
rare DX station respond, such as VP8LP in the Falkland Islands.
"I was on 12-meter SSB the first night hams in the USA were
authorized to use the band in 1985. That night, the band was wild
because of a big sporadic-E opening and strong signals were coming
from all directions across North America. It was a blast!
"I am fortunate to have a decent station -- 8-element log periodic
antenna up 50 feet from a hilltop QTH with a kilowatt amp. But many
signals were so strong on September 14 that I am sure others with
modest stations could work many DX stations. I had to QRT at 1356
UTC even though others were still calling. I got back on the band
later in the day and worked MW0ZZK in Wales. He was 20 over S9.
"Don't forget about 12 meters. When 10 meters is open, 12 is open
too. And don't forget about the phone band allocation, which starts
at 24.930 MHz in the USA. I've heard some out of band because they
didn't know where the band edge was.
"A great propagation tool is the MUF web page operated by KC2G at
https://prop.kc2g.com/ . I monitor it constantly. It tells me what
bands to check out and where I should aim my antenna. Plus, it has
other interesting data in the menu."
Thanks to Dave for mentioning that great web site. I notice it has a
section labeled eSSN, which is Effective Sunspot Number, derived
from 10.7 cm solar flux. More about eSSN from NorthWest Research
Associates, based here in the Seattle area:
Also, I would like to add that often 12 meters is open when 10
meters seems dead.
Here is more crazy solar news:
Here is Newsweek again:
Some solar wind news:
Lucky us! A brand new video, dated today, from Dr. Tamitha Skov,
Send your tips, reports, observations, questions, and comments to
For more information concerning shortwave radio propagation, see
http://www.arrl.org/propagation and the ARRL Technical Information
Service at http://arrl.org/propagation-of-rf-signals . For an
explanation of numbers used in this bulletin, see
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/ .
Instructions for starting or ending email distribution of ARRL
bulletins are at http://arrl.org/bulletins .
Sunspot numbers for September 8 through 14, 2022 were 75, 72, 122,
113, 117, 93, and 57, with a mean of 92.7. 10.7 cm flux was 126.6,
126.2, 135.9, 151.5, 150.4, 154.1, and 144.3, with a mean of 141.3.
Estimated planetary A indices were 19, 13, 12, 9, 9, 4, and 9, with
a mean of 10.7. Middle latitude A index was 17, 14, 10, 9, 9, 5, and
10, with a mean of 10.6.