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ARRL Propagation Bulletin ARLP017 (2022)

ARLP017 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 17  ARLP017
From Tad Cook, K7RA
Seattle, WA  April 29, 2022
To all radio amateurs 

ARLP017 Propagation de K7RA

At 0206 UTC on April 28 the Australian Space Forecast Centre issued
a Geomagnetic Disturbance Warning: "The Earth is currently under the
influence of moderately elevated solar wind speed associated with a
southern coronal hole. On late UT day April 29, solar wind
conditions are expected to enhance further due to possible arrival
of the 27 April CMEs. G0-G1 conditions are likely for next three
days with a chance of G2 on April 29 due to both coronal hole
effects and impending impact of the CMEs. Aurora may be visible from
Tasmania, southern coastline Victoria and southwest Western

On Wednesday and Thursday, I am seeing sunspot groups threaded
across the Sun from southeast to northwest. Daily sunspot number
peaked at 126 on Tuesday, and average daily sunspot number for the
week was 109.3, up from 64.4 last week. Daily solar flux peaked at
164.4 on Thursday, April 21 and the average for the week was 156, up
from 133.9 in the previous week.

Predicted solar flux is 125, 115 and 110 on April 29 through May 1,
105 on May 2-4, 102 on May 5-6, then 130 and 128 on May 7-8, 130 on
May 9-10, 135 on May 11-12, 140 on May 13-15, 160 on May 16-21, 135
on May 22, 132 on May 23-25, 125 on May 26-27, 130 on May 28-31, 125
on June 1, and 130 on June 2-3.

Predicted planetary A index is 18, 10 and 8 on April 29 through May
1, 5 on May 2-5, then 8, 15, 12 and 8 on May 6-9, 5 on May 10-12,
then 8, 10, 8 and 8 on May 13-16, 5 on May 17-19, then 10 and 8 on
May 20-21, 5 on May 22-25, then 18, 12 and 8 on May 26-28, then 5 on
May 29 through June 1, and 8, 15, 12 and 8 on June 2-5.

OK1HH says:

"Last week we witnessed higher solar activity. Large active areas
passed through the central meridian and produced medium-sized
eruptions (class M) and occasionally large eruptions (class X).
While at the end of the period these areas in the northwest were
sinking, other and slightly smaller areas in the southeast of the
disk emerged.

"There have been two increases in geomagnetic activity - one was
expected on the night of April 20-21, second one, rather unexpected,
by afternoon of April 27.  The gradual increase in solar radiation
has significantly improved the propagation conditions of decameter
waves. Its improvement was supported by the positive storm phase
during the afternoon of April 27, when the critical frequencies of
the F2 ionospheric layer in mid-latitudes exceeded 10 MHz and MUF on
transatlantic routes rose above 30 MHz. The negative storm phase
followed on April 28."

Decameter waves is another term for HF radio, at 3-30 MHz.

Watching sunspots on the sidewalk in New York City:

A story on how to watch sunspots (safely, of course) without a

Bill, KD9KCK wrote:

"On Wednesday, April 27 around 2100 UTC 10m was having some
propagation I have never dreamed of. I was tuning around looking for
a spot to call CQ for Parks On The Air and came across EA2K and
another station in Spain talking to ZL1ACE in New Zealand. And I was
able to hear both sides here near Chicago with just a short 36 inch
10m hamstick on the roof of my car with my IC-718. I didn't try to
contact the EA stations once they called QRZ though because they
were looking for just Pacific Stations at the time."

Here is a story of a "Tornado of Fire" on the surface of the Sun:

K4ZOT wrote on Tuesday, April 26:

"Just wanted to drop you a quick line about today's unusual
propagation on 17M to Eastern Europe - Kosovo and Croatia, Central
Asia - Kyrgyzstan, Japan, far NT in Canada, SA - Brazil, North
Atlantic - Faroe Island, etc. - well really all over the world.
This was quite unusual in my book and unexpected. Worked two ATNO -
Republic of Kosovo and Faroe Island. I am running a TS-590SG into a
mini-beam at only 20 feet with an amp at 300 watts. All contacts
were on FT8. It was quite an experience!"

NN4X reported from Florida on April 26:

"I experienced some amazing conditions on 10m
over-the-north-pole-or-darn close propagation today, all using FT8.

"9N7AA 1220 UTC (20 degree heading; the others were within a few
degrees of 0)

"YC1KQV 1222 UTC 
9M2TO 1613 UTC
9W2TED 1633 UTC 
9V1ZV 1714 UTC
E20EHQ 1818 UTC

"There was at least one other 9W2 that I missed, and other YBs which
I did not call.

"Also, in there was BD9BI/0 (Zone 23).  I'd worked him previously,
so did not pursue him.

"I am not sure I've ever seen such an extended period of this kind
of propagation on 10m."

Here is some information on flares and radio blackouts:

I (K7RA) noticed plenty of odd propagation this week, possibly due
to flare activity. I use FT8 mainly as a tool for observing
propagation on various bands, and on Tuesday April 26 at 1652 UTC
K7HAM in Arizona answered my CQ on 17 meters. But we did not
complete the contact. showed broad coverage of my
signal, from Southern California to Florida at the south, and South
Dakota to Maine at the north. But at 1700 UTC coverage began to

By 1720 UTC my coverage on the map was all gone, with a couple of
odd exceptions.

WZ7I in Pennsylvania and AF7KR in Arizona were the only stations
reporting my signal. Then suddenly NH6V on Hawaii's Big Island
reported. That was it, but then I observed F1EYG and DL0PF on my

After 1721 UTC my coverage began coming back. I stopped calling
K7HAM at 1730 UTC, 38 minutes after he responded to my CQ, and by
1735 UTC my signal was being received again all over North America.

On Wednesday, April 27 at 1730 UTC checking for any FT8 signals on
10 meters from my grid square (CN87), they were only being received
in Florida! Nowhere else, anywhere, and the cluster of Florida
stations reporting was quite thick, stretching all over the state.
But nowhere else was reporting signals from my area.

More on radio blackouts:

Don't know what they mean by "sunspot activity score of 80," the
average of daily sunspot numbers for the past four weeks is 68.2:

Here is the latest from Dr. Tamitha Skov, WX6SWW:

If you would like to make a comment or have a tip for our readers,
please email the author at,

For more information concerning shortwave radio propagation, see and the ARRL Technical Information
Service web page 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 21 through 27, 2022 were 119, 101, 118,
112, 94, 126, and 95, with a mean of 109.3. 10.7 cm flux was 164.4,
162.5, 159.8, 158.5, 156.6, 148.9, and 141.5, with a mean of 156.
Estimated planetary A indices were 10, 7, 13, 5, 5, 3, and 21, with
a mean of 9.1. Middle latitude A index was 9, 7, 12, 5, 4, 3, and
16, with a mean of 8.


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