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ARRL Propagation Bulletin ARLP033 (2022)

ARLP033 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 33  ARLP033
From Tad Cook, K7RA
Seattle, WA  August 19, 2022
To all radio amateurs 

ARLP033 Propagation de K7RA

At 2334 UTC on August 17, the Australian Space Weather Forecast
Centre issued a geomagnetic disturbance warning.

"Periods of G1 conditions expected during 19 and 20 Aug due to the
combination of coronal hole high speed wind stream and several
coronal mass ejections observed in the last few days.  There is a
chance of isolated periods of G2 over 19 and 20 Aug."

Local TV newscasts here in Seattle noted the possibility of aurora
Thursday night, although observers would need to travel to dark
areas away from the city for any chance of successful viewing.  They
recommended using a tripod mounted camera pointed north with a long
exposure time.  This is good advice, as often the dramatic aurora
photos are done this way, and viewing with the naked eye you see a
much less dramatic image.

Last week we noted increasing solar activity, and it continued.
Average daily sunspot numbers increased from 36.6 to 65.4 last week,
to 95.6 in the current reporting period, August 11 to 17.  Average
daily solar flux went from 95.7 to 111.9 last week, and 123.7 this

But solar flux values have pulled back in recent days, with a peak
of 134.3 at 1700 UTC on August 15, followed by the standard 2000 UTC
local noon readings of 128.5, 122.7, and 116.5 on August 16 to 18.

Predicted solar flux is 125 and 120 August 19 and 20, 115 on August
21 to 23, then 110 on August 24 and 25, then 100, 94, 96 and 98 on
August 26 to 29, then 100, 108 and 114 on August 30 through
September 1, then 116 on September 2 and 3, 112 on September 4, 108
on September 5 and 6, then 115, 120, 124 and 126 on September 7 to
10, 124 on September 11 and 12, then 122, 118, 112, 108 and 102 on
September 13 to 17, then 100 on September 18 and 19, and 94 on
September 20 to 23, then climbing to 116 at the end of the month.

Predicted planetary A index is 30, 25 and 8 on August 19 to 21, 5 on
August 22 to 26, 12 on August 27, 8 on August 28 to 30, 5 on August
31 through September 2, then 24, 28, 18 and 10 on September 3 to 6,
and 14, 8, 10 and 8 on September 7 to 10, then 5, 5, 20 and 15 on
September 11 to 14, then 12, 12 and 8 on September 15 to 17, and 5
on September 18 to 22, then 12 on September 23, and 8 on September
24 to 26.

OK1HH writes:

"A week ago (since August 12) solar activity started to increase
very slowly.  Since August 13, the eruptive activity in the active
sunspot AR3079 in the southwest of the solar disk has increased.  On
August 14 it was already possible to predict massive geomagnetic
disturbances for August 17 and 18 based on the observed CMEs.  The
solar wind speed slowly decreased until August 16.  In the meantime,
eruptive activity increased in AR3078, where moderate strength
eruptions were observed daily since 15 August.

The sunspot group AR3078 developed a delta-class magnetic field,
continued to grow, and continued to produce medium-sized flares that
caused minor shortwave radio blackouts.  The strongest eruption to
date, an M5 category burst on August 16 at 0758 UTC caused a
shortwave radio blackout over the Indian Ocean.

A series of coronal mass ejections (CMEs) added their effect to a
possible 'cannibal CME event' (if a second CME could overtake and
engulf the first, creating a mishmash of the two).  The forecast for
a massive geomagnetic disturbance has been extended to August 17 to

Active sunspot AR3078 is producing strong solar flares of class M
for the third consecutive day.  The most recent, an M2 explosion on
17 August (1345 UT), hurled a plume of cool dark plasma into space.
But like the other CMEs produced by AR3078 this week, this one will
pass through the southern edge of Earth's impact zone.  So the
disturbance won't be as widespread as if the CME had hit Earth

The increased activity on 15 to 17 August caused improved shortwave
propagation conditions and a noticeable increase in MUF.  The best
day was August 17.  A significant deterioration and decrease in MUF
occurred on 18 August.  In the following days, the solar flare
activity and the intensity of geomagnetic disturbances start to
decrease.  A calming trend can be expected after about 22 August."

Tamitha Skov says "Don't worry, this is not a Carrington Event", in
an 84 minute video titled "Incoming Solar Storm Crush":

Even Newsweek is reporting it:

And of course, British tabloids:


Violent solar activity:

Strong storm:

Aurora in Montana:

Radiation storm!

John Kludt, K7SYS asked, "I recently moved from the Atlanta,
Georgia, area to Sandpoint, Idaho.

My question is that in geomagnetic forecasts they make a distinction
between 'mid-latitudes' and 'high-latitudes.'   Where do
'mid-latitudes' stop and 'high-latitudes' begin?

The other mystery to me is looking at my logbook since moving here
two years ago, it would seem I was working more Dx at solar cycle
minimum than I am now.  The station is the same for the entire
period and all of the numbers I track on my antennas are stable.

One of the conclusions I have come to, maybe incorrectly, is 'The
good news is the sun is more active and the bad news is the sun is
more active.'   As with so many things, there is no free lunch."

My response: I don't know of any standards specifying what defines
high latitude or low latitude, except for North America, Atlanta at
33.8 degrees north would be low latitude, Sandpoint at 48.3 degrees
would be moderately high for North America, and Fairbanks, Alaska at
64.8 degrees would be high.

I remember years ago K7VV was living in Alaska and reported to me
that during a particularly long period of high geomagnetic activity,
there just was no HF propagation, due to the concentration of the
disturbance closer to the poles.

You might notice better propagation from Atlanta.  I've noticed
using on 10 meters FT8, looking at the "country of
callsign" setting, often it shows lots of propagation from the SE
states and nothing here in the northwest.  Don't know why that is,
but gradually the propagation will drift out this way.  So Atlanta
being 3 hours earlier will show 10 meter propagation before we get
it here.  It seems to me that often HF propagation from southern
states is better than it is here for us in the Pacific Northwest,
what Jack Bock, K7ZR (SK) referred to as the "sufferin' sevens".

Send your tips, reports, observations, questions and comments to

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 August 11 through 17, 2022 were 58, 97, 116,
104, 92, 119, and 83, with a mean of 95.6.  10.7 cm flux was 114.8,
119.5, 124.2, 125.5, 130.6, 128.5, and 122.7, with a mean of 123.7.
Estimated planetary A indices were 16, 7, 10, 7, 6, 5, and 31, with
a mean of 11.7.  Middle latitude A index was 12, 6, 10, 9, 6, 5, and
22, with a mean of 10.


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