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ARRL Propagation Bulletin ARLP041 (2020)

ARLP041 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 41  ARLP041
From Tad Cook, K7RA
Seattle, WA  October 9, 2020
To all radio amateurs 

ARLP041 Propagation de K7RA

Geomagnetic activity quieted down over this past reporting week,
October 1 to 7. Compared to the previous seven days, average daily
mid-latitude A index declined from 15.6 to 6, and average planetary
A index slipped from 22 to 7.1.
There were no sunspots this week and only one in the previous seven
days. Average daily solar flux went from 73.4 to 71.8.
But late Thursday (October 8) two new cycle 25 sunspots appeared.
They are both in the southern hemisphere, and as of this writing
have yet to be assigned numbers. Check here for early images:
Later tonight (Friday) you can check to see the
official sunspot number. You can check here Friday night to see the
daily sunspot numbers and daily total sunspot area over the last
I just hope this activity isn't like recent spots, which made only
brief, faint appearances.
Predicted solar flux over the next 45 days is 72 on October 9 to 14,
70 on October 15 to 18, 72 on October 19 to 31, 70 on November 1 to
14, and 72 on November 15 to 22.
Predicted planetary A index is 5 on October 9 to 19, then 10, 18, 20
and 24 on October 20 to 23, then 16, 38 and 38 on October 24 to 26,
then 26, 15 and 10 on October 27 to 29, then 5 on October 30 to
November 6, 10 on November 7, and 5 on November 8 to 15, then 10,
18, 20 and 24 on November 16 to 19, and 16 on November 20 and 21,
then 38 on November 22.
Geomagnetic activity forecast for the period October 09 to November
04, 2020 from F. K. Janda, OK1HH.
"Geomagnetic field will be 
Quiet on: October 16, 18, November 2 
Quiet to unsettled on: October 9 and 10, 12 to 14, 17, 31, November
3 and 4 
Quiet to active on: October 15, 19 and 20, 28 and 29, (30,) 
November 1
Unsettled to active: October 11, 21 to 24, 27 
Active to disturbed: October 25 and 26 
Solar wind will intensify on: October 13, (14 and 15, 20 and 21,)
22, (23 and 24,) 25 to 29, (30,) November 2 to 4.
Parenthesis means lower probability of activity enhancement."
Word from NASA about a new look at sunspots:
Leif Svalgaard predicts a slightly better cycle 25:
Has the pandemic affected amateur radio activity? Yes, and in a good
All that isolation seems to allow more time on the air, if HF
contest activity is any indicator.
From Jon, N0JK in Kansas:
"Some weak sporadic-E from Kansas to Florida October 6 around 1900Z.
But stations further east had some outstanding propagation.
Stations in Ecuador worked north to the Gulf Coast, then New England
on 6 Meters.
Propagation mode?
F2 can occur in early October between North America and South
America. But solar flux only 71 and no major geomagnetic activity.
Multi-hop Sporadic-E may have been the mode. Some sporadic-E was
spotted from New England to Florida, and Florida to Mexico. Es are
rare in October, too.  An unusual opening.
HC2FG    20/10/06 2104Z  50313.0 still in FN44 Maine  K1TOL     
HC3AP    20/10/06 2103Z  50314.4 FT8                  W4AS       
HC3AP    20/10/06 2100Z  50313.0 CQ                   XE1MEX-
HC1BI    20/10/06 2055Z  50313.0 73                   KW4BY     
HC1BI    20/10/06 2051Z  50314.2 FT8                  KD5M       
HC1BI    20/10/06 2046Z  50313.0 FT8 Maine            K1TOL     
HC2FG    20/10/06 2046Z  50313.0 73                   KW4BY     
HC1BI    20/10/06 2045Z  50314.2 FT8                  W4AS       
HC2FG    20/10/06 2037Z  50313.0 FT8 Maine            K1TOL     
HC2FG    20/10/06 2035Z  50313.0                      WB2TQE     
HC2FG    20/10/06 2033Z  50314.7 FT8                  KD5M"
Jeff Hartley, N8II writes from the state of West Virginia: 
"I just finished the CA QSO Party. Saturday 15M was very marginal; I
made about 20 QSOs. Today, 15M condx were excellent to all of CA
from 1640 to 1850Z enabling me to work about 110 total 15M Qs. 80
and 40M were excellent to CA with the 40M peak about 30 to 60
minutes before their sunset Saturday evening. Some signals on 80
were quite loud and the CA guys were hearing my 200W very well.
Also, signals were still good to CA almost 2 hours after my sunrise
today on 40M. 20M was very poor at 2200-2300Z Saturday, but
improved enough for me to run 20M SSB stations 2300-2340Z. I noticed
some possible sporadic E to central TN and KY in the afternoon on
20M (also some unexpected IL stations late morning)."
Tamitha Skov, WX6SWW explains the cause of recent geomagnetic
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 October 1 through 7, 2020 were 0, 0, 0, 0, 0, 0,
and 0, with a mean of 0. 10.7 cm flux was 72.8, 72.2, 71.8, 71.2,
72.3, 71.7, and 70.7, with a mean of 71.8. Estimated planetary A
indices were 11, 9, 6, 4, 8, 7, and 5, with a mean of 7.1. Middle
latitude A index was 11, 6, 5, 3, 7, 6, and 4, with a mean of 6.


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