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ARRL Propagation Bulletin ARLP032 (2020)

ARLP032 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 32  ARLP032
From Tad Cook, K7RA
Seattle, WA  August 7, 2020
To all radio amateurs 

ARLP032 Propagation de K7RA

Sunspot cycle 25 is well underway. We saw one new spot last week, on
July 28, and two new ones this week on August 2 and 3. The daily
sunspot numbers were 22 and 23 on the dates of their appearance, and
the total sunspot area grew on Wednesday to 160 millionths of the
visible solar disc.
The total sunspot area was smaller the next day, August 6, but the
daily sunspot number increased from 13 to 14.
Sunspot area has not been as large since May 2019, when it ranged
from 140 to 410 millionths of the solar disc over a two week period.
Average daily sunspot number for July 30 to August 5 was 19.6, up
from 14.1 over the previous seven days. Average daily solar flux
rose from 71.1 to 72.8 over the same period.
The A index remained about the same, with planetary A index barely
increasing from 6.7 to 7 and mid-latitude A index declining slightly
from 8.7 to 7.4.
Predicted solar flux is 73 on August 7 to 9, 71 on August 10 to 14,
69 on August 15 to 17, 71 on August 18 to 25, 73 on August 26 to 30,
71 on August 31 to September 7, 69 on September 8 to 13, and 71 on
September 14 to 20.
The planetary A index forecast is 5 on August 7, 8 on August 8, 5 on
August 9 to 23, 8 on August 24 and 25, 5 on August 26 to 28, then
12, 8 and 8 on August 29 to 31, 5 on September 1 to 19 and 8 on
September 20.
Geomagnetic activity forecast for the period August 7 til September
2, 2020 from F. K. Janda, OK1HH.
"Geomagnetic field will be 
Quiet on: August 7 (-8,) 12, 15 and 16, September 2  
Quiet to unsettled on: August 9, 11, 13 and 14, 17 to 19, 22, (23 to
27,) 28 and 29, September 1
Quiet to active on: (August 10, 20 and 21)  
Unsettled to active on: August (30 and 31) 
Active to disturbed: not expected 
Solar wind will intensify on: August (10 and 11, 22 23,) 24 and 25,
September 1 and 2
- Parenthesis means lower probability of activity enhancement. 
- The predictability of changes remains lower because there are few
indications, moreover, in new active areas."
Geomagnetic conditions have been very quiet and stable for a long
time, and this week is the first time in recent memory that OK1HH
predicted any unsettled to active conditions.
Frank Donovan, W3LPL noted in an August 5 email that "Today marks
the longest stretch of consecutive days with sunspots since
September 2017 when there were 56 consecutive days."
"The next solar cycle 25 milestone will be an energetic sunspot
region that increases the adjusted SFI to 80 or higher. Fingers and
toes crossed..."
WJ5O has an interesting history of 10 meter sporadic-E and info on
Frequent contributor Ken Brown, N4SO writes to us from the Gulf
Coast in Grand Bay, Alabama.
He noted an announcement about the Reverse Beacon Network map
display in the ARRL Letter, with this link: 
"On a 'Dead Band', I get the following from a series of CQ's. 
W8WTS  N4SO 21035.1 CW CQ 4 dB  28 wpm 1722z 06 Aug  70 seconds ago 
KO7SS  N4SO 21033.1 CW CQ 23 dB 28 wpm 1721z 06 Aug   2 minutes ago 
W3UA   N4SO 21033.1 CW CQ 13 dB 28 wpm 1721z 06 Aug   2 minutes ago 
W3RGA  N4SO 21033   CW CQ 23 dB 28 wpm 1721z 06 Aug   2 minutes ago 
W3RGA  N4SO 21035   CW CQ 20 dB 28 wpm 1721z 06 Aug   2 minutes ago 
K1TTT  N4SO 21035   CW CQ  6 dB 28 wpm 1720z 06 Aug   3 minutes ago"
"On CW, 21 MHZ CW frequencies will often appear dead from 21.000 to
21.060 MHZ.
For a quick propagation check, I will often use W1AW on their CW
On 21 MHZ, I use the W1AW Schedule, for Code Practice or Code
Bulletins on 21.0675000 MHZ. The 3 PM (5 August) code practice, for
example, had no signals at all, and the Reverse Beacon Network did
not show a Spot for 5 August, and confirms no signals. On several 
good days in the past there are signals just above the noise level
to about S1 or S2.
28 MHZ has a broadcast on 28.0675000 MHZ. In addition to propagation
checks, I use the signals from W1AW for a frequency calibration
On Reverse Beacon Network, I will often do a W1AW 'Spot' check,
which shows dates and times past history, for W1AW and the
frequencies when they were spotted."
David Moore sent this link from Science Daily about our quiet sun
being much more active than it appears: 
Occasionally we ponder past geomagnetic storms which were so huge,
if they occurred today with our dependence on technology it seems as
if they could end life as we know it. In the past, they have even
appeared during periods of otherwise low sunspot activity. Here is
one to think about: 
An astrophysicist's obituary: 
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
Instructions for starting or ending email distribution of ARRL
bulletins are at
Sunspot numbers for July 30 through August 5, 2020 were 22, 23, 22,
22, 23, 12, and 13, with a mean of 19.6. 10.7 cm flux was 73.3,
72.3, 72, 72.7, 72.7, 73, and 73.4, with a mean of 72.8. Estimated
planetary A indices were 4, 4, 3, 9, 16, 8, and 5, with a mean of 7.
Middle latitude A index was 5, 5, 3, 9, 15, 9, and 6, with a mean of


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