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ARRL Propagation Bulletin ARLP015 (2020)

ARLP015 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 15  ARLP015
From Tad Cook, K7RA
Seattle, WA  April 10, 2020
To all radio amateurs 

ARLP015 Propagation de K7RA

After five days of new cycle 25 sunspot activity, sunspots vanished.
Average daily sunspot number rose from 3.6 last week to 5.1 this
time.  The average daily sunspot number over the days they were
visible, March 31 through April 4, was 12.2, but these observations
straddled two reporting weeks.
Average daily solar flux rose from 69.4 to 70.2.  Geomagnetic
indicators remain quiet, with average planetary A index declining
from 7.7 to 6.6, and average mid-latitude A index slipping from 5.9
to 5.3.
Predicted solar flux for the next 45 days is 70 on April 10 to 13,
68 on April 14 to 23, 70 on April 24 through May 7, 68 on May 8 to
20, and 70 on May 21 to 24.
Predicted planetary A index is 8 on April 10 and 11, 5 on April 12
to 14, 10 on April 15, 8 on April 16 to 19, 5 on April 20 to 25, 10
on April 26 and 27, 5 on April 28 through May 6, 8 on May 7 and 8, 5
on May 9 to 11, 10 on May 12, 8 on May 13 and 16, 5 on May 17 to 22
and 10 on May 23.
F. K. Janda, OK1HH wrote:
"Geomagnetic activity forecast for the period April 9 to May 5, 2020
Geomagnetic field will be  
Quiet on: April 10, 20 and 21, May 2 and 3  
Quiet to unsettled on: April 11 to 13, 17 and 18, 22 to 24, 28 and 29  
Quiet to active on: (April 9, 14, 16, 25, May 1)  
Unsettled to active on: (April 15, 19, 26 and 27, 30, May 4 and 5)  
Active to disturbed: nothing predicted 
Solar wind will intensify on:  April 9, 12 and 13, (15 and 16,) 17 to
19, (20,) 26 to 28, May 4 to 6
- Parenthesis means lower probability of activity enhancement.  
- The predictability of changes remains lower as there are no
Tamitha Skov, WX6SWW is excited about signs of cycle 25:
Frank Donovan, W3LPL sent this out to the Potomac Valley Radio Club
yesterday, and shared it with us for this bulletin:
"Some of us have noticed a slight uptick in solar activity since
Christmas Day when when two Cycle 25 spots -- AR 2753 and AR 2754 --
appeared.  Only one of the five subsequent sunspots -- AR 2757 --
has been from old Cycle 24.  All of the sunspots over the the last
12 months have been relatively weak and have had little affect on
Although the beginning of Cycle 25 won't be officially declared
until late this year, its highly likely that it began on Christmas
Day 2019.
The next important event to look for is a strong Cycle 25 sunspot,
hopefully that will occur this year."
Jon Jones, N0JK wrote yesterday:
"With the early start to the summer sporadic-E season, some Es are
linking from North America to South America.
On April 9, LU9FF and LU9FVS spotted K4CVL on 50.313 MHz FT8 at
2230z.  K4TR and NN4X in South Florida spotted stations in Chile.
Signals were strong enough for SSB with AC4TO EM70 working CA3SOC
and LU8YD on 50.110 MHz SSB at 2224z.
KN4NN, AA5AU and N0FW (EM79) Ohio were also making FT8 contacts with
South America on 6 meters."
KA3JAW monitors 11 meters, (That's right, Citizens Band!) for
interesting propagation events from Easton, PA (FN20jq):
"Sporadic-E was up on eleven meters on Tuesday, April 7 from 6:45
until 11:00 pm local (ET).
During this event, the Es funnel path coned me stations only from
the coastal Gulf of Mexico states of Louisiana, Mississippi,
I find it somewhat strange that Es remains active up till late
nightly hours during the opening of Spring season.
I thought Tuesday, March 31 was a good DX day monitoring the 11
meter band with reception of Tyler, Texas at 1,254 miles.
But today, Saturday, April 4 was way more exciting with reception of
multiple Puerto Rico stations rolling-in from 6:42 pm local (ET)
until 8:00 pm that were 374+ miles further in range.
One operator there was making greater than 1,600 miles contacts from
West Virginia up into Rhode Island.
Around local sunset at 7:29 pm the baseline background noise level
environment jumped 30 dB when one particular operator running high
power would key the microphone.
Puerto Rico operators would occasionally peak 20 dB over local
The distance from my QTH to San Juan, Puerto Rico runs 1,628 miles.
This would be considered to be at the far end range of a single-hop
sporadic-e path.  Perhaps the plasma cloud was tilted a few degrees
from horizon."

I've been using the FT8 mode with WSJT-X software to observe
marginal propagation modes, in which communication occurs due to
refraction via whispery ionized clouds.  Using low power and a
deliberately marginal antenna (short piece of wire, thrown out the
basement window, never more than 4 feet above ground) I can
immediately see signal reports from many stations via .  Some of the results on
160 through 10 meters seem quite remarkable, considering the antenna
and power level.
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 2 through 8, 2020 were 12, 13, 11, 0, 0,
0, and 0, with a mean of 5.1.  10.7 cm flux was 69.8, 69.9, 70.1,
71.2, 69.9, 69.9, and 70.4, with a mean of 70.2.  Estimated
planetary A indices were 7, 9, 5, 5, 3, 4, and 13, with a mean of
6.6.  Middle latitude A index was 7, 7, 4, 4, 2, 3, and 10, with a
mean of 5.3.


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