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ARRL Propagation Bulletin ARLP015 (2022)

ARLP015 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 15  ARLP015
From Tad Cook, K7RA
Seattle, WA  April 15, 2022
To all radio amateurs 

ARLP015 Propagation de K7RA

At 2335 UTC on April 14, the Australian Space Forecast Centre issued
this Geomagnetic Disturbance Warning: 


Sunspot numbers and solar flux declined this reporting week (April
7 to 13) although solar activity wasn't really down. Instead, we saw
solar flares and CMEs every day, causing disruptions to HF radio

There was a new sunspot appearance on April 7, and another on each
day from April 11 to 14. Yet average daily sunspot numbers declined
from 94.6 to 34.4, and average daily solar flux from 135.3 to 103.1.

Average daily planetary A index increased from 14.4 to 15.9, and
average middle latitude A index (measured at a single magnetometer
in Virginia) went from 10.9 last week to 12.6 this week.  

The latest solar flux prediction from the USAF Space Weather
Squadron, via NOAA, shows modest activity for the next month with
flux values of 105 and 110 on April 15 and 16, 115 on April 17 to
20, 118 on April 21, 110 on April 22 and 23, 115 on April 24, 118 on
April 25 to 28, 116 on April 29 through May 6, 112 and 98 on May 7
and 8, 95 on May 9 to 11, 98 and 102 on May 12 and 13, 106 on May 14
to 18, and 110 on May 19 and 20.

Predicted planetary A index is 22, 15, 10, 12 and 10 on April 15 to
19, 5 on April 20 to 22, then 15, 10 and 8 on April 23 to 25, 5 on
April 26 to 28, then 18, 12 and 8 on April 29 through May 1, 5 on
May 2 to 5, then 8, 15 and 12 on May 6 to 8, then 5 on May 9 to 11,
then 12 and 8 on May 12 and 13, 5 on May 14 to 16, then 10 on May 17
and 18, then 5, 15, 10 and 8 on May 19 to 22.

I've noticed odd 10 meter propagation lately, possibly affected by
the heightened geomagnetic activity. On April 14 in the local
Seattle morning around 1530 UTC using FT8 and it
seemed that my low power signal was only being heard along a narrow
band across the Gulf Coast, from Texas to South Caroline. Later I
was only being heard in Florida.

Then all reports disappeared, then suddenly reports extended to two
stations in Columbia and Chile, and by 2000 UTC I was heard by W5SRO
in Oklahoma, KX4WB in Tennessee, N4HER in North Carolina, and KB2AHZ
in Virginia, plus everything in between, and then as far south as
KN5X in Texas across to KD7NFR in Georgia, plus most of Central

By 2300 to 0100 UTC, other than local stations and W7MTL, 250 miles
away in Oregon, I was only being heard in Mexico, by five stations
1700 to 2300 miles away.

On the same afternoon, Jon Jones, N0JK reported on six meters, "Due
to a CME impact, the geomagnetic field went to storm levels the
afternoon of April 14.

6 Meters opened to Ecuador around 1930 UTC. Here in eastern Kansas,
HC2DR and HC2FG were loud on 50.313 MHz FT8. They were in about an
hour with big pileup. I received a psk flag from HC2FG at 2003 UTC.
AA0MZ EM29 worked HC2DR and HC2FG."

Earlier Jon reported:

"I copied on 50.313 MHz FT8 April 9:


CE3SOC peaked to '-9 dB.'

No contacts."

On April 14, Dick, K7BTW reported to the Western Washington DX Club

"A bit of an opening to SA on 6 FT8 this afternoon. I worked CE2SV
(VE7SV) Dale Green down there in Chile.

I have copied several stations from down in Chile the past few days
about 2000 to 2130z."

Jay, K7TTZ forwarded this piece from Newsweek on solar cycle

OK1HH says:

"Solar activity has been declining over the last week. We now
observe only two active areas in the northeast quadrant of the solar
disk.  However, we experienced two coronal mass ejections (CME). The
one first originated from the filament eruption on April 11, while
the arrival of coronal mass to the surroundings of the Earth with a
significant increase in geomagnetic activity is expected during
April 14. The second CME on April 13 took place on the far side of
the Sun and is heading for the planet Mercury.

The STEREO A probe observes three other active areas behind the
eastern edge of the solar disk. Solar activity is starting to rise.
It can be assumed that it will be increased throughout the second
half of April. A more significant decline is not expected at the
beginning of May either."

Solar cycle progress and aurora:


Interesting info on helioseismology

Another wonderful video from WX6SWW:

For more information concerning shortwave radio propagation, see and the ARRL Technical Information
Service at For an
explanation of numbers used in this bulletin, see

An archive of past propagation bulletins is at More good
information and tutorials on propagation are at

Instructions for starting or ending email distribution of ARRL
bulletins are at .

Sunspot numbers for April 7 through 13, 2022 were 52, 55, 37, 13,
24, 23, and 37, with a mean of 34.4. 10.7 cm flux was 111.1, 108.9,
107.1, 101.1, 98.7, 96.2, and 98.7, with a mean of 103.1. Estimated
planetary A indices were 15, 9, 19, 34, 13, 12, and 9, with a mean
of 15.9. Middle latitude A index was 12, 9, 17, 18, 13, 10, and 9 ,
with a mean of 12.6.


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