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ARRL Propagation Bulletin ARLP026 (2021)

ARLP026 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 26  ARLP026
From Tad Cook, K7RA
Seattle, WA  June 25, 2021
To all radio amateurs 

ARLP026 Propagation de K7RA

Average daily sunspot number was 14 this reporting week (June
17-23), essentially unchanged from last week's 13.9. Average daily
solar flux increased from 75.2 to 79.3.

Geomagnetic indicators were quieter. Average planetary A index
declined from 9.6 to 5.3, and average middle latitude A index
dropped from 9.7 to 6.1.

Predicted solar flux is 82 on June 25 to July 1, then 80 and 78 on
July 2-3, 75 on July 4-7, 78 on July 8-11, 75 on July 12-16, 78 on
July 17-22, 75 on July 23-25, and 78 on July 26-30.

Predicted planetary A index is 5 on June 25 through July 3, 12 on
July 4, 5 on July 5-8, 8 on July 9-10, then 5, 15 and 12 on July
11-13, 5 on July 14-20, 8 on July 21, and 5 on July 22-30.

Sunspot group 2833 is about to rotate over our Sun's western
horizon, but I see promising activity around and beyond the eastern
horizon when viewing the STEREO mission images at .

Also check to see this emerging

Check the 2300 UTC June 22 solar flux reading from the Dominion
Astrophysical Observatory at and note that
the value jumped way up to 104.5. The official solar flux for that
day was the noon reading, 80.8 at 2000 UTC. (A munged version of
this URL was in Thursday's ARRL Letter. My fault, for not testing

Geomagnetic activity forecast for the period June 25 to July 22,
2021 from OK1HH.

"Geomagnetic field will be,
quiet on: June 27-28, July 1, 11, 16-17,
quiet to unsettled on: June 25-26, July 6, 10, 14-15, 18-22,
quiet to active on: June 29-30, July 2-3, 7, 9,
unsettled to active: July 4-5, (8,) 12 (- 13),
active to disturbed: nothing forseen.
"Solar wind will intensify on: June (29,) 30, July (2,) 3-5, (9,)
10-12, (13-15, 18-20).

"Parenthesis means lower probability of activity enhancement."

Steve Gregory, VK3OT sent details of a remarkable 6 meter opening on
June 23 from Ukraine to Australia. He posted an image on his
page. Look him up!

Steve sent info on other openings from UB7K in Crimea, all reports
were using FT8 mode.

KA3JAW looks for sporadic-E propagation on the FM broadcast band:

"Kyle Whitley from Moses Lake, Washington (DN07hc) received audio
with RDS capture on an over-the-air FM broadcast, 90.5, Spirit FM,
WBVM, Tampa, Florida via double-hop sporadic-E on June 17 at 0135
UTC (1835 PDT).

"That is 2377 miles distance. I believe that is a US record for 2XEs
on that frequency.

"He is the only Washington state FM-DX'er that I am aware of that
nailed Florida.  During the event, he was hearing and locking onto
RDS from multiple Kanas stations via single hop Es.

"The odd part, is that he only heard that one station (WBVM) along
that line-of-bearing path towards Kansas, then dropping into
Florida.  The most amazing detail is that he used a portable SPARC

"WBVM FCC Technical Data:

"259 meters (850 ft) Above Ground Level

"- Tower/Antenna 100 kW Effective Radiated Power

"- Transmitter -

"Player spot: 02:39 | 90.5 WBVM Tampa, FL."

The United States Postal Service has new postage stamps with solar

Dr. Tamitha Skov, WX6SWW, has a new video:

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 June 17 through 23, 2021 were 12, 24, 15, 13,
11, 12, and 11, with a mean of 14. 10.7 cm flux was 85, 77, 77.1,
76.4, 79.1, 80.8, and 79.7, with a mean of 79.3. Estimated planetary
A indices were 7, 7, 4, 4, 4, 7, and 4, with a mean of 5.3. Middle
latitude A index was 9, 8, 5, 4, 3, 8, and 6, with a mean of 6.1.


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