Propagation Forecast Bulletin 19 ARLP019
From Tad Cook, K7RA
Seattle, WA May 13, 2022
To all radio amateurs
SB PROP ARL ARLP019
ARLP019 Propagation de K7RA
We saw some evidence of sporadic-e propagation this week on 6 and 10
meters, always surprising and exciting.
Solar activity was about the same as last week, at least going by
Average daily sunspot numbers rose slightly from 68.6 to 74.4, while
average daily solar flux only budged from 120 to 120.3.
Geomagnetic indicators were quieter, with average daily planetary A
index shifting from 10.7 to 5, and average middle latitude numbers
from 9.3 to 4.6. We listed the middle latitude A index on May 6 as
2, but that number is my own estimate. At the end of that day the
last K index reading was not reported, and since the A index for the
day is calculated from all the K index readings, there was no
official middle latitude A index reported, so I came up with my own
estimate based on available data.
Thursday’s outlook for solar flux is more optimistic than last
week’s prediction, with no values below 100. Expected flux values
are 135 on May 13-16, then 132, 128, 126, and 120 on May 17-20, then
118, 120, 124 and 121 on May 21-24, 118 on May 25-27, 116 on May
28-31, 118 on June 1-5, then 116 and 118 on June 6-7, 120 on June
8-9, 122 on June 10-14, 118 on June 15-17, then 120, 124 and 121 on
Planetary A index is predicted at 8 on May 13, 12 on May 14-15, then
14 and 8 on May 16-17, 5 on May 18-19, then 12 and 8 on May 20-21, 5
on May 22-23, 18 on May 24, 15 on May 25-27, 8 on May 28, and 5 on
May 29 through June 15, a nice long quiet spell of geomagnetic
stability for more than 2 weeks.
Thursday’s forecast was prepared by Trost and Housseal of the U.S.
“Solar flares continue to occur, and some of them are throwing
several overlapping CMEs into space. The amount of CMEs leaving the
sun is large enough to make it difficult to unravel their different
shapes and trajectories, which reduces the reliability of
predictions. Nevertheless, the geomagnetic activity is mostly low,
which can be explained by the fact that the magnetic fields above
the solar surface are mostly closed.
An intense solar flare of class X1.5 was observed on May 10 at 1355
UT in the active region 3006 with a complex magnetic structure.
Radiation from the flare ionized the Earth’s atmosphere and caused a
shortwave radio outage around the Atlantic Ocean, more specifically
from Central Europe to the east coast of the United States (see
Dellinger effect). Radio transmissions at frequencies below 30 MHz
were attenuated for more than an hour after the eruption.
Another M-flare on the afternoon of May 11 was a proton flare.
Another CME on May 11 came from the sunspots on the far side – one
just behind the eastern limb of the Sun and the other just behind
the western limb. We do not expect the solar wind around the Earth
to intensify again.”
Here is a blackout map for the above mentioned May 10 event:
Mystery of the bright spots:
WA6LIE wrote in a message titled “TEP to Fiji”:
“Yesterday evening March 10 just after 0600 UTC I was getting ready
to go to bed and saw 3D2AG calling CQ on 6 meter FT8.
I gave him a call and we made a QSO.
He was decoded here in Salinas CA. CM96 for an hour and a half with
Looks like the Magic band is starting to play!
Will go back to my saying: gotta be in the right place at the right
time and get lucky! Heads up!”
“Today (05/07/2022) at 1601 UTC, I caught a brief 2-meter E-skip
opening and worked W4AS in EL95, using FT8, 25 Watts, and an indoor
mobile whip antenna. It was an 1100-mile hop from EM10, in Austin
TX, to the Miami FL area. He was +04 here and I was -24 there, no
doubt because of my low power and cross-polarization. It was a new
grid for me on 2, and I’m happy to have it.”
Massive solar flare, almost:
Solar cycle progress update from NOAA:
Real time geomagnetic updates:
Latest from Space Weather Woman Dr. Skov, WX6SWW:
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 May 5 through 11, 2022 were 85, 64, 66, 89, 71,
62, and 84, with a mean of 74.4. 10.7 cm flux was 119.9, 119.2,
118.1, 119.2, 117, 115.8, and 132.9, with a mean of 120.3. Estimated
planetary A indices were 4, 5, 3, 6, 8, 3, and 6, with a mean of 5.
Middle latitude A index was 4, 2, 4, 7, 8, 2, and 5, with a mean of
(via Mike Terry via WOR io group)