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ARRL Propagation Bulletin ARLP021 (2019)

ARLP021 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 21  ARLP021
From Tad Cook, K7RA
Seattle, WA  May 24, 2019
To all radio amateurs 

ARLP021 Propagation de K7RA

May 18 was the last day we saw sunspot activity, after more than two
weeks with daily sunspots visible.  Average daily sunspot number
declined to 5.3 this week following 22.7 during the previous week.
Average daily solar flux declined from 75.7 to 69.8.
Geomagnetic conditions were quieter, with average daily planetary A
index declining from 13 to 5.
Predicted solar flux over the next 45 days is 67 on May 24 to 31, 74
on June 1, 76 on June 2 to 10, 74 on June 11, 72 on June 12 and 13,
70 on June 14 and 15, 69 on June 16 and 17, 68 on June 18, 67 on
June 19 to 25, 70, 72 and 74 on June 26 to 28, then 76 on June 29
through July 7.
Predicted planetary A index is 5 on May 24, 8 on May 25, 5 on May 26
and 27, then 10, 12, 8 and 8 on May 28 to 31, 5 on June 1 to 15, 8
on June 16 to 18, 5 on June 19 to 23, then 10, 12, 8 and 10 on June
24 to 27, and 5 on June 28 through July 7.
Geomagnetic activity forecast for the period May 24 to June 19, 2019
from F. K. Janda, OK1HH.
"Geomagnetic field will be: 
Quiet on May 27, June 2, 4 and 5, 14 and 15, 18 
Quiet to unsettled on May 25 and 26, June 1, 6, 9 and 10, 17, 19 
Quiet to active on May 24, 30 and 31, June 3, 7 and 8, 12 and 13, 16 
Unsettled to active on May 28 and 29 
Active to disturbed on June (11) 
Solar wind will intensify on May 29 to 31, June 1, (10 to 12)
Parenthesis means lower probability of activity enhancement."
On May 20, Markus Hansen, VE7CA wrote:
"Today I have been hearing many California beacons on 10 meters as
well as K7EMX/B in Utah.  So I have been calling CQ on 28005.00 for
several hours and not one single answer to my calls.
I have also been listening to AE6RQ's SDR and my signal has been
between 579 and 20 over S 9 from 1700 to 2100Z.  I don't have a 6
meter antenna up right now but wish I did.
I expect many have migrated to FT-8 etc.  Sad, being an old timer I
still love the sound of CW.
I appreciate your propagation reports.  I copy them regularly on CW
via W1AW."
Max White, M0VNG sent this piece on Earth's moving magnetic North
Scott Avery, WA6LIE in Salinas, California reported a nice sporadic
E opening on 6 meters during Mother's Day, May 12.
"We had a good opening from 1430-2030 UTC here in Salinas CM96.  Had
a lot of FT8 activity logging 45 contacts there and 6 QSOs on SSB.
Conditions were very wild for a bit on SSB with multiple QSO's on
the same frequency ie:  50.130, 50.135 etc.  That lasted for about 2
hours after about 1600z.
Worked all I heard and worked many grid squares.  The MAGIC band...
got to luv it."
K9LA recently updated a 2007 article he wrote for WorldRadio on
ionospheric sounders, which were referenced in recent bulletin
The link to data from ionospheric sounders provided in ARLP019:
Note that you can re-order the table by clicking on any of the
For instance, at 0740 UTC on May 17 if I click on the foF2 column, I
can sort the ionosondes by foF2 values and discover that the
ionosonde on Cocos Island has the highest foF2 value, at 10.465 MHz.
Number 2 is Guam at 8.588 MHz, followed by Rome, Italy.
Later at 0850 UTC those values were 11.56 MHz, 8.6 MHz and 6.95 MHz.
In only an hour, propagation changes.
The latest from Dr. Skov:
This weekend is the CQWW WPX contest, details here:
If you would like to make a comment or have a tip for our readers,
email the author at,
For more information concerning radio propagation, see 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
Monthly propagation charts between four USA regions and twelve
overseas locations are at
Instructions for starting or ending email distribution of ARRL
bulletins are at
Sunspot numbers for May 16 through 22, 2019 were 13, 13, 11, 0, 0,
0, and 0, with a mean of 5.3.  10.7 cm flux was 73.6, 72.1, 70.6,
68, 68.7, 68, and 67.3, with a mean of 69.8.  Estimated planetary A
indices were 8, 5, 5, 3, 6, 4, and 4, with a mean of 5.  Middle
latitude A index was 9, 7, 8, 3, 7, 4, and 5, with a mean of 6.1.


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