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ARRL Propagation Bulletin ARLP014 (2021)

ARLP014 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 14  ARLP014
From Tad Cook, K7RA
Seattle, WA  April 2, 2021
To all radio amateurs 

ARLP014 Propagation de K7RA

Average daily sunspot numbers declined this week from 17.9 to 11.9.
Why? Because on the final two days of the March 25-31 reporting week
sunspots disappeared. That's right. We're back to the blank Sun
again, unfortunately. reported on Wednesday that we may soon see a
potential sunspot currently on the far side of our Sun. They
presented this image:

Average daily solar flux dropped from 78.6 to 77.4. Geomagnetic
indicators softened as well, with average daily planetary A index
declining from 13.3 to 8.9, and middle latitude A index from 10.4 to

Predicted solar flux over the next month does not look promising,
with values way down in the seventies, although this forecast
improved some over the past couple of days. Expect 10.7 cm flux at
73 on April 2-3, 71 on April 4-9, 73 on April 10-13, 74 on April
14-16, 76 on April 17-24, 75 on April 25-27, then 74 and 73 April
28-29, and 72 on April 30 through May 5.

Predicted planetary A index is 5 on April 2-5, 8 on April 6-7, then
5, 10 and 20 on April 8-10, then 5 on April 11-15, then 20 and 18 on
April 16-17, 8 on April 18-19, 5 on April 20-21, 8 on April 22-24,
12 on April 25, 8 on April 26-27, 5 on April 28-30, then 8 on May
1-2, 5 on May 3-4 and 12 on May 5-7.

Geomagnetic activity forecast for the period April 2 to 27, 2021
from OK1HH.
"Geomagnetic field will be: 
quiet on: April 12-13, 24-26 
quiet to unsettled on: April 5, 14, 23 
quiet to active on: April (2-7, 15, 20-22, 27) 
unsettled to active: April (8, 11, 18-19) 
active to disturbed: April (9-10,) 16-17 
"Solar wind will intensify on: April 3, (4-5, 8-9,) 10-11, (12,
16-17,) 18, (19-22, 27).
- Parenthesis means lower probability of activity enhancement. 
- Predictability of changes remains very low, as there are ambiguous
  and quickly changing indications."

Here is an article from "The Irish Times" about space weather and
the sinking of the Titanic:

NN4X reported a 15 meter long path opening to Asia: "Nice opening to
Asia here in Central Florida on the morning of 4/1/2021.

"On FT8, I worked BA7LP, YD7ACD, BG7PHA, and VR2VLY, and heard 9V1PL
and BD7LMA.

"It was very concentrated - note no JA/HL/DU. Typically, I've been
seeing more YBs than anything on 15M LP, but certainly not today.

"Anyway, it's all great fun, and I thought I'd pass it along!"

Many years ago we reported in this bulletin results JQ2UOZ was
getting running 1/2 watt using simple wire antennas on his apartment
balcony.  Check out his blog:

Another blast from the past on flares and CMEs:

An article in "The Conversation" about predicting space weather:

An article about why we are still hearing about that Carrington
Event - even after all these years - can be found here:

AL7LO has a collection of his favorite ARRL Propagation Forecast
Bulletins, and he shared this one recently from 8 years ago:

If you would like to make a comment or have a tip for our readers,
please email the author at, .

For more information concerning shortwave radio propagation, see and the ARRL Technical Information
Service web page 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 March 25 through 31, 2021 were 24, 24, 11, 11,
13, 0, and 0, with a mean of 11.9. 10.7 cm flux was 78.8, 79.6,
80.4, 75.1, 74.4, 79.5, and 73.8, with a mean of 77.4. Estimated
planetary A indices were 18, 12, 9, 6, 4, 3, and 10, with a mean of
8.9. Middle latitude A index was 18, 11, 7, 4, 3, 4, and 7, with a
mean of 7.7.


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