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ARRL Propagation Bulletin ARLP028 (2021)

ARLP028 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 28  ARLP028
From Tad Cook, K7RA
Seattle, WA  July 9, 2021
To all radio amateurs 

ARLP028 Propagation de K7RA

Solar activity continues its increase.  In last week's bulletin
ARLP027 average daily sunspot number was 34.7, and this week it
increased to 55.6.

Average daily solar flux increased from 86.9 to 88.9.

Despite solar flare activity pushing a sudden ionospheric
disturbance and a dramatic shortwave radio blackout, at least the
average daily planetary A index for the week was only 5.7, down from
6.1 in last week's bulletin.  The average middle latitude A index
was also 6.1 last week, and it was 6.3 this week.

The flare was an X1.5-Class event, the biggest since September 2017
and the only X-Class solar flare since then.  Readers asked, "What
was that?"

Scott Craig, WA4TTK wrote, "What happened about 1430 UTC on July 3?
Some people on a forum are saying it was a massive solar flare.  I
was on 20 meter FT8 and my waterfall display went from solid red
signals to solid nothing in the blink of an eye.  It lasted about 10

Events such as this can be so dramatic many have an initial reaction
assuming there was a major hardware failure in their radio, or maybe
their antenna blew down or was destroyed by lightning.  Fortunately,
these are rare.

W3LPL sent an excellent written narrative on this event, but his
report was covered yesterday in the ARRL Letter, so I won't repeat
it here.

The event received some coverage outside the usual channels:

Of course, Tamitha Skov, WX6SWW our Space Weather Woman reported

Love her enthusiasm, as well as her solid science reporting.

Predicted solar flux is 73 on July 9 to 13, 72 on July 12 and 13,
then 72 on July 14 and 15, 76 on July 16, 82 on July 17 and 18, 84
on July 19, 88 on July 20 to 22, 90 on July 23 to 28, 88 on July 29
through August 2, 84 on August 3, 82 on August 4 and 5, 80 on August
6 to 11, and 82 on August 12 to 14.

Predicted planetary A index is 5 on July 9 and 10, then 8, 12, 16,
12, and 8 on July 11 to 15, 5 on July 16 and 17, then 15, 12 and 10
on July 18 to 20, 5 on July 21 to 31, then 10 and 8 on August 1 and
2, 5 on August 3 to 5, then 15 and 12 on August 6 and 7, and 5 on
August 8 to 13.

Geomagnetic activity forecast for the period July 9 til August 5,
2021 from Frantisek K. Janda, OK1HH, of the Czech Propagation
Interested Group compiling this geomagnetic activity weekly forecast
since January 1978.
"Geomagnetic field will be 
Quiet on: July 14, 16 to 18, 21, 23 to 25, 28, 30 and 31, August 3
to 5 
Quiet to unsettled on: July 9 and 10, 15, 22, 29, August 1 and 2 
Quiet to active on: July 11, 13, 19 and 20, 26 and 27 
Unsettled to active: July 12 
Active to disturbed: none predicted

Parenthesis means lower probability of activity enhancement."

Bob McHenry, G3NSM wrote:

"On July 5, I was amazed to work KL7HBK at 1447 UTC on 50.323 MHz
FT8.  John is in Anchor Point, BO49, which is just south of
Anchorage and I was beaming on the short path, 345 degrees.  It
wasn't a marginal contact.  John was in for 10 minutes and gave me a
report of +05 which suggests he might have heard me on CW.  I
believe John also worked into France, Italy and EA6 the same day.
He confirmed the contact with me on LOTW the next day.

Contacts between Alaska and Europe on 6m are very rare and John was
the only signal coming through from that region.  There were no W6,
W7 or VE7 stations audible as there had been on the previous day."

Thanks, Bob.  I will check for any reports from July 4.

Jeff Hartley, N8II in West Virginia wrote:

"Between increased SFI and plentiful sporadic E it was a fun week on
the bands.

The RAC Canada Day contest July 1st started with a good evening
opening on 40M to all nearby areas of Canada.  I worked about 65
stations in Ontario and Quebec, mostly on SSB.  Sunday morning
around 1400 to 1845 UTC there was very intense sporadic E into all
provinces from Ontario east to Newfoundland on all bands, including
10 meters.  Normally Ontario is skipping over me on 20M.  I worked 9
provinces on 15 CW, 10 on SSB, 8 on 10M CW, 9 on SSB. Even Labrador
was worked on 15 SSB.  The highlight was a run of 5 British Columbia
stations on 10M CW at 1700.  VE1 through VE9 except VE8 and VY2
Prince Edward Island were all logged on 10 SSB.

On July 2 starting 1340 UTC, I worked 3 English stations and PA1CC
from the Netherlands on 10M Es.  TM13COL special French call for 13
colonies on the air was worked on 12M CW with a strong signal.  Then
at 1455 UTC amid many New England QSO's on 10M I worked 2 Italians
and MM0TFU in Scotland.  At 1533UTC I found LY4A Lithuania (new band
slot) on 10m SSB and also Germany.

17M was open late at 2340 UTC to Poland and S9 EI3GIB in Ireland on
the 3rd.  On the 4th at 2048 UTC HB90BERO in Switzerland was S9 on
15M SSB.  I heard two Lebanese stations as well with OD5ZZ peaking
S6, but no QSO's.  At 2017 SO1WS Western Sahara was logged on 17M
SSB followed by V73NS Marshall Is.  on 17 CW who was working Denmark
and Portugal over the North Pole.  At 2200 UTC 17M was still wide
open working Switzerland, Moscow Russia, Slovenia, HI95RCD Dominican
Republic, and G3YPZ in England.  G3YPZ moved up to 15M where he was
S5 on SSB followed by S9+ IK4GRO in Italy.  On the 5th at 2212 on 15
CW KH0W Mariana Is. was weak over a tough path from here and CT3MD
Madeira was S9 plus.  On the 6th at 1750 UTC SP9FMP was marginally
worked on 10M CW.  ZA1E in Albania was weak Q5 and stations very
close to him in Europe were heard working him for about 15 minutes."

The ARRL Contest Update reported, on July 7:

"Six meters has been exciting over the last week or so, with reports
of excellent inter-continental propagation.  US hams have been
enjoying many contacts with Asia and the EU.  Craig, K9CT, worked a
few new ones on July 2: 'Six meters was amazing today. DXCC total
for 6m went from 128 to 141.' The Pacific Northwest has even been
getting in on some of the action, with some stations reporting new
countries worked on 6 even with antennas like 'a 20 meter dipole
with an antenna tuner.' You can't work them if you don't try."

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 July 1 through 7, 2021 were 56, 72, 81, 60, 43,
52, and 25, with a mean of 55.6.  10.7 cm flux was 94.1, 94.9, 93.7,
91.1, 89.4, 83.2, and 76, with a mean of 88.9.  Estimated planetary
A indices were 7, 5, 4, 3, 7, 8, and 6, with a mean of 5.7.  Middle
latitude A index was 7, 6, 4, 4, 9, 8, and 6, with a mean of 6.3.


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