SB PROP @ ARL $ARLP020
ARLP020 Propagation de K7RA
QST de W1AW
Propagation Forecast Bulletin 20 ARLP020
From Tad Cook, K7RA
Seattle, WA May 20, 2022
To all radio amateurs
SB PROP ARL ARLP020
ARLP020 Propagation de K7RA
Solar activity was up, up, up this week, with average daily sunspot
numbers increasing from 74.4 to 134.1, and average daily solar flux
from 120.3 to 157.3.
To get some perspective, I averaged the weekly averages for sunspot
number and solar flux from this bulletin and the previous three,
then compared them to the bulletins from one year earlier.
A year ago, the averages for 2021 Propagation Forecast Bulletins
ARLP017 through ARLP020 were 28.9 for sunspot numbers and 75.9 for
solar flux. A year later, the averages are 96.6 for sunspot numbers
and 138.4 for solar flux.
This documents a substantial increase in solar activity and is
another illustration of how this cycle is progressing faster than
the official cycle prediction by the experts.
Geomagnetic indicators were higher this week. Average daily
planetary A index went from 5 to 9, while middle latitude A index
increased from 4.6 to 9.6, compared to the previous reporting
period, which always runs from Thursday through the following
Spaceweather.com reported on Wednesday that big sunspot AR3014
doubled in size, and presented this movie from NASA, showing 24
hours of activity:
On Thursday, Spaceweather.com presented this movie of a massive jet
of plasma projecting from our Sun's southwestern limb:
Predicted solar flux in Thursday's prediction begins about 8 points
lower than the Wednesday forecast, at 172 on May 20, 170 on May
21-24, then a decline from 168, 166, 150, 136, and 138 on May 25-29,
then the predicted values revert back to the Wednesday forecast at
140 on May 30-31, 143 on June 1-3, 140 and 136 on June 4-5, 138 on
June 6-7, then 140 and 150 on June 8-9, 154 on June 10-12, 152 on
June 13-14, then 150 and 148 on June 15-16, 140 on June 17-18, 145
on June 19, 142 on June 20-21, then 138 on June 22 and 136 on June
Predicted planetary A index is 12 on May 20, 8 on May 21-22, 5 on
May 23-26, 15 and 8 on May 27-28, 5 on May 29 through June 9, 8 on
June 10, 14 on June 11-12, 8 and 5 on June 13-14, 8 on June 15-16, 5
on June 17-19, 18 on June 20, then 15 on June 21-23, 8 on June 24,
and 5 for at least the following ten days.
The above predictions are from Housseal and Levine of the 557th USAF
The Sun busts out a trio of flares:
"In the last seven days, solar activity has risen monotonously."
(I thought F.K. Janda's use of the word "monotonously" must be a
mistranslation, but now I am not so sure. I thought perhaps he meant
"Moderate flares have been observed almost daily. Highest level
X-rays belonged to an X1.5 class eruption, start 1350 UTC, peak 1355
UTC, end time 1359 UTC on May 10th from NOAA AR 3006 in the
southwest quadrant, classified as magnetic type beta-gamma-delta.
"During the daytime, moderate flares often caused a Short-Wave
Fadeout. AR 3007 and AR 3014 also evolved into the beta-gamma-delta
"No fibrous eruption was observed in any of the fibers on the solar
disc. Observed coronal holes were relatively small, for this reason
too, the geomagnetic activity was mostly low. The expected arrival
of a CME, related to the flares of classes X1.5 and C4.7 on 10 May
did not arrive on Earth.
"The decrease in geomagnetic activity together with the increase in
the intensity of solar X-rays contributed to the fact that the
critical frequencies of the ionospheric layer F2 were above average,
increased further since 15 May."
"Here is the Solar activity forecast for the period May 20-26, 2022:
"Activity level: mostly moderate
X-ray background flux (1.0-8.0 A): in the range C1.4-C2.6
Radio flux (10.7 cm): a fluctuation in the range 145-195
Events: class C (1-10/day), class M (1-8/period), class X
(0-3/period), proton (0-1/period)
Relative sunspot number (Ri): in the range 140-230
"Jana Hrabalova, RWC Prague Astronomical Institute."
"Geomagnetic activity forecast for the period May 20-26, 2022:
"Quiet: May 21-23
Unsettled: May 19-20, 24-26
Active: May 19, 24
Minor storm: possible May 24
Major storm: 0
Severe storm: 0
"Geomagnetic activity summary:
"Today (Thursday, May 19), unsettled to active conditions are
expected. On Friday, May 20, we expect at most unsettled conditions
until Saturday, May 21. From this day to Tuesday, May 24, quiet to
unsettled conditions are expected.
"About Tuesday, May 24, and Wednesday, May 25, the return of the
unsettled conditions may be accompanied by a further active event."
"Tomas Bayer, RWC Prague, Institute of Geophysics, Department of
Geomagnetism, Budkov observatory."
KB1AWM wrote on Sunday, May 15:
"Had a nice short opening to VK6OZ on 12m from Charleston, SC at
0330 UTC tonight. The mode was FT8. What was most amazing was given
that late night propagation is usually not conducive to 12m, I
switched on the amp and received a +17 dB signal report. If you take
out the 7 dB from the amp, that still leaves +10 dB barefoot. I'm
enjoying these 10 and 12 meter openings!"
I replied: "I've been seeing interesting stuff on 12 meters as well.
Frequently during the day on FT8 I will see my signal from here in
Seattle on pskreporter ONLY being received in Florida. Weird!"
On Tuesday, May 17 on 12 meter FT8 starting at 2130 UTC I was only
heard by CX6VM in Uruguay (6,945 miles), WH6S on Kauai (2,723 miles)
and 3D2EZ Fiji (5,834 miles).
This persisted until 2145 UTC when I was heard by WQ6Q in California
On Thursday, May 19 I used FT8 to observe propagation on 10 meters
using pskreporter.info from 1530-1600 UTC. Local sunrise was 1231
UTC. During that half hour I was receiving no signals at all, but my
low power signal was being received by many stations, only in the
Western United States, all between 700-1200 miles away, with one odd
exception, a mysterious WLO in EM50vo, 2149 miles from me in
WLO turned out to be the callsign of an old Coastal Maritime station
in Mobile, Alabama. This doesn't mean that they are on the 10 meter
band with that callsign, but instead have a receiver monitoring the
band and forwarding received info via WSJT-X.
Check out this web site:
Interesting web site - the Solar Influences Data Center:
The Solar Terrestrial Centre of Excellence:
Here is a site that talks about 17 flares:
Here is an article titled "Solar flares: What are they and how do
they affect Earth?" with nice graphics:
If you would like to make a comment or have a tip for our readers,
For more information concerning shortwave radio propagation, see
http://www.arrl.org/propagation and the ARRL Technical Information
Service web page 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 May 12 through 18, 2022 were 112, 120, 105, 129,
173, 153, and 147, with a mean of 134.1. 10.7 cm flux was 133,
149.5, 152.7, 153.6, 161.7, 170.8, and 179.9, with a mean of 157.3.
Estimated planetary A indices were 8, 7, 7, 12, 10, 12, and 7, with
a mean of 9. Middle latitude A index was 8, 7, 9, 10, 11, 15, and 7,
with a mean of 9.6.