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ARRL Propagation Bulletin ARLP018 (2020)

ARLP018 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 18  ARLP018
From Tad Cook, K7RA
Seattle, WA  May 1, 2020
To all radio amateurs 

ARLP018 Propagation de K7RA

There were several sunspot appearances this week. Sunspot numbers on
April 25 to 29 were 11, 14, 12, 0 and 24, giving a weekly average of
8.7. Average daily solar flux changed from 69 to 69.2.
Geomagnetic activity remains quiet, with average daily planetary A
index declining from 7.3 to 5.6.
On Thursday, new sunspot activity continued, with the daily sunspot
number for April 30 at 35, and the total sunspot area four times
what it was on April 25 to 27. This new activity is both encouraging
and exciting.
Predicted solar flux is 70 on May 1 to 5, 69 on May 6 to 16, 70 on
May 17 to 31, 69 on June 1 to 12, and 70 on June 13 and 14.
Predicted planetary A index is 5 on May 1 and 2, then 8, 8, 10 and 8
on May 3 to 6, 5 on May 7 to 17, then 10 and 8 on May 18 and 19, 5
on May 20 to 23, 8 on May 24 to 27, 5 on May 28 to 31, 12 on June 1,
5 on June 2 to 13, and 10 on June 14.
Geomagnetic activity forecast for the period May 1 to 26, 2020 from
F. K. Janda, OK1HH.
"Geomagnetic field will be 
Quiet on:  May 2 and 3, 13 and 14, 26 
Quiet to unsettled on:  May 1, 6 to 8, 15 and 16, 25 
Quiet to active on:  (May 4, 9 and 10, 17, 20, 22, 24) 
Unsettled to active on:  May 5, (11 and 12, 18 and 19, 21, 23) 
Active to disturbed:  None predicted
Solar wind will intensify on: May (4,) 5 and 6, (11 and 12,) (18 to
21, 23,) 24
- Parenthesis means lower probability of activity enhancement.  
- The predictability of changes remains lower as there are no
Michael Guerin, W6MVT of Upland, California wrote:
"The evening of 27 April 2020 was an odd one for those of us in
Southern California. After the end of the Florida QSO Party twenty
meters became very quiet here. Yet in the evening around 0300 UTC
the only three signals heard were there ZL1's - ANH, BD and WN. Each
courteously received each of us and we enjoyed pretty clear
(uncontested) time with our neighbors to the southwest. Like having
an exclusive pipeline. Nice change."
KB1DK from Trumbull, Connecticut wrote:
"On Saturday morning April 25th between 1350 and 1430z, I listened
to YB0AZ and YB0IBM working stations in the Midwest on 14.190 and
14.210 respectively. Both stations were armchair copy, S8 to S9 on
an inverted vee OCFD. Those lucky enough to work YB0IBM also got to
QSO his friends YB1DNF and HS0ZOA. YB0AZ said that it has been
nearly a year since he worked stateside stations. Nothing was heard
this morning (4/26). I did not make contact with either station.
On 17 meters, ZL1WN is a regular on 18.150 to 18.160 between 2100
and 2130z. I have been hearing Ross on most afternoons with a strong
S8 to S9 signal though the QSB can get pretty bad.
I always look forward to your report.
Stay safe and healthy."
Thank you. I think it is interesting that YB0AZ says it has been
nearly a year since he last worked USA stations. He should be
hearing from North America more often as the sunspot cycle picks up.
Sean, K8KHZ wrote:
"40 Meters was great April 18th at 0100z. I was able to work EA8BWW
Canary Islands. I used a very low in height inverted G5RV with just
100 watts on SSB. I was surprised the band was open. I was testing
the station out for the annual Michigan QSO Party."
Be sure to check the current issue of ARRL Letter for comments by
K9LA on differences between historic sunspot numbers. The link is .
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 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
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 April 23 through 29, 2020 were 0, 0, 11, 14, 12,
0, and 24, with a mean of 8.7. 10.7 cm flux was 68.7, 69.7, 68.9,
69.2, 69, 69, and 69.9, with a mean of 69.2. Estimated planetary A
indices were 4, 8, 5, 6, 7, 6, and 3, with a mean of 5.6. Middle
latitude A index was 4, 6, 5, 5, 6, 6, and 4, with a mean of 5.1.


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