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ARRL Propagation Bulletin ARLP022 (2021)

ARLP022 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 22  ARLP022
From Tad Cook, K7RA
Seattle, WA  May 28, 2021
To all radio amateurs 

ARLP022 Propagation de K7RA

The 10.7 cm solar flux rose this week, and on Wednesday May 26 it
reached 88, the highest since December 7, 2020, when it was 89.5.

The next day the 2300 UTC flux value was 94.2.

The official flux value is always the local noon reading at Canada's
Dominion Radio Astrophysical Research Facility (see ) in Penticton, British Columbia, 177 miles
northeast of my Seattle QTH.  You can see the thrice daily readings
at .

Average daily solar flux rose this week to 77.8 from last week's
average of 74.2, while the average daily sunspot number increased
from 20.3 to 24.9.

I hope this signals a return to the enhanced activity and HF
conditions we saw at the end of 2020, and a resumption of solar
cycle 25's upward climb.

Predicted solar flux over the next month is 83, 81, 80 and 76 on May
28 to 31, 72 on June 1 to 3, 73 on June 4, 74 on June 5 to 10, 75 on
June 11, 77 on June 12 to 15, 79 on June 16 to 23, and 76 on June 24
to 29.

Predicted planetary A index is 10, 5, 8, 5 and 8 on May 28 through
June 1, then 5 on June 2 and beyond, possibly into mid-July.

Geomagnetic activity forecast for the period May 28 til June 22,
2021 from F. K. Janda, OK1HH.
"Geomagnetic field will be 
Quiet on:  May (30 and 31,) June 9 and 10, 12 and 13  
Quiet to unsettled on:  June 1 to 8, 17 to 20
Quiet to active on:  May 28 and 29, June 11, 14 to 16, 21 and 22
Unsettled to active:  Nothing predicted
Active to disturbed:  Nothing predicted
Solar wind will intensify on May 28 to 30, June (7,) 9, (14 and 15,
17 to 19, 22)
- The increased geomagnetic activity on May 26-27 was due to solar
flares with CME on May 22.  Therefore, it could not be predicted last
time, ie on May 20.
- Parenthesis means lower probability of activity enhancement.
- Accuracy of the forecast remains lower."

Jon Jones N0JK reports from Kansas:

"The summer 2021 sporadic E season is off to a strong start.  Here
in Kansas I had Europe in on 6 Meters May 19.  DK1MAX peaked to -3
dB with audible tones at 1540z.  Earliest I have had Europe on 6
Meter Es.

May 26 Hawaii to the Midwest on 6 Meters.  KF0M (EM17) in Wichita,
KS had KH6CJJ on Maui up to -4 dB around 2000z.  The Hawaiians were
in over an hour."

The mode was FT8.

"Hi Tad --

Quite a surprise for the solar flux to jump up into the 80s and then
the 90s today (Thursday).

I was trying out a modified small HF loop (homebrew) on my kayak in
the Mokelumne River in Northern California today and wasn't getting
out very well.  Then I thought I'd give 17m SSB a final try before
packing up my gear.  Transmitter power was 12 watts.

Heard two VKs coming in loud and clear, and managed to catch VK2CPC,
Les, just as he finished a QSO.  He gave me a 3-3 report and managed
to get my call sign correct.  Fortunately my kayak was in such a
position that the loop was aimed toward Australia.

And, my buddy caught two bass.  Good day for both of us.

bil paul, KD6JUI
Dixon CA"

Michael May, WB8VLC in Oregon reported:
"Another weird week of non ham activity on 10 meters to report along
with lots of 6 meter activity.
The most interesting thing heard on 10 meters was not ham contacts.
It was non ham intruders heard this past Sunday while tuning around
10 meters looking for beacons when I came across some North Korean
fishing boats operating on 28.175 and 28.275 MHZ FM mode.
This was at 2120 UTC May 22, 2021 and the signals were in for the
next 2 hours.  The attached recording is condensed from over a 2
hour period.  (email K7RA for a 836 KB MP3 copy.)

A co-worker listened to the recording and said it sounds like a
North Korean dialect and after more research we found that they are
most likely squid fishing boats around the Asiatic Russian coast
north of Japan and east of mainland Asiatic Russia, where these
boats are typically found.
The signals peak on my 4 el 10 meter OWA at 330 degrees.
I have not heard these signals in over 9 years which leads me to
think that a 10 meter FM path to Japan is possible, research on
these boats indicates only 25 watts of FM carrier with 102 inch
No real interesting 10 meter ham contacts to list as the North
Korean fishing boats is certainly enough for my 10 meter listing.
6 meters was my best band over the past 2 weeks for real ham to ham
QSOs and here are some of the interesting ones.

All of the 6 meter SSB contacts were well over S9 both ways and the
QSOs lasted for over 45 minutes each, real rag chews.
On 6 meters SSB/FT8/CW I use my K3S to a 6 element high gain Yagi on
the same boom as my 4 elements for 10 meters and 500 watts from a
home made LDMOS amplifier.
On 6 meter FM I use the Hygain V-6R stacked 5/8th wave, 25 foot long
co-linear vertical and 110 watts with a GE Orion FM land mobile
6 meter contacts, all times/dates UTC:

2021-05-18  0327 KH6HI   50.313    FT8 BL01xi
2021-05-19  0420 VE8CK   50.313    FT8 DP22TK
2021-05-22  0241 W5WTX   50.090    CW  DM95cc
2021-05-23  1859 VE3WN   50.313    FT8 FN03ht
2021-05-24  0035 W0VTT   50.098    CW  EN33xx
2021-05-24  0120 TI2ALF  50.313    FT8 EJ79xv
2021-05-26  0229 KG4HOT  50.180    SSB FM07pt
2021-05-26  0232 KD4AA   50.180    SSB FM17ur
2021-05-26  0243 WB7PMP  50.180    SSB EM95pu
2021-05-26  0335 KA6NLS/rptr 51.940 FM DM35cd Kingman, AZ
2021-05-26  1525 VA3IKE  50.313    FT8 EN82qb"

N1API reported last week: "I suppose by now you have heard of the 6
meter opening on May 19.  I was fortunate to work a total of 59
stations on FT8.  The most amazing thing was that band was still
open into Europe at 10 PM Local which would be 2 AM or later in
Europe depending on how deep the opening was.  Stations from the US
were also seen.  The next morning at daybreak had signals from Spain
and Italy on 6 meters.  I can't remember seeing conditions like this

N4SO reports: "In the weird category, my signal was picked up on
Pskreporter in Ukraine.  The notation, a one and ONLY, reads as

Rx at Monday, 17 May 2021 18:08 GMT
From N4SO BY UX0ZAB Loc KN66au15
Frequency 28.074.741 MHz (10m) FT8 -13DB
Distance 9552 km bearing 36 degrees

The map location shows Ukraine.  At that time, I was transmitting,
both calling CQ, and working mostly USA.  UX0ZAB, is a monitoring
station and we did not make a contact, other than his reception
report of my signal.  I realize that UX0ZAB is not a Ukraine call
sign but they move around a lot."

Check this web site for synoptic map images:

It has been a long time since we presented a link to an article
about the important work of astronomer Hisako Koyama:

Thanks to K5FB for these links on long term solar flux prediction:

New solar telescope planned for Canary Islands:

News from WX6SWW, Dr. Tamitha Skov, the Space Weather Woman:

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 May 20 through 26, 2021 were 13, 13, 19, 30, 29,
36, and 34, with a mean of 24.9.  10.7 cm flux was 72.3, 73.7, 75.6,
79, 72.7, 83.5, and 88, with a mean of 77.8.  Estimated planetary A
indices were 24, 7, 5, 4, 4, 3, and 13, with a mean of 8.6.  Middle
latitude A index was 17, 8, 5, 4, 2, 3, and 12, with a mean of 7.3.


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