QST de W1AW  
Propagation Forecast Bulletin 17  ARLP017
>From Tad Cook, K7RA
Seattle, WA  April 26, 2024
To all radio amateurs 

SB PROP ARL ARLP017
ARLP017 Propagation de K7RA

'ASWFC GEOMAGNETIC DISTURBANCE WARNING ISSUED AT 0733 UTC/26 APRIL
2024 BY THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE.

'A coronal hole wind stream has moderately enhanced the solar wind
speed and been associated with several hours’ worth of southward IMF
parameter Bz. For this reason, it is possible that periods of G1-G2
geomagnetic storm conditions may be observed.

'INCREASED GEOMAGNETIC ACTIVITY EXPECTED DUE TO CORONAL HOLE HIGH
SPEED WIND STREAM FROM 26-27 APRIL 2024:

'GEOMAGNETIC ACTIVITY FORECAST
26 Apr:  G0, slight chance G1-G2
27 Apr:  G0, slight chance G1
 
'Australian Space Weather Forecasting Centre.'

After a big jump in solar activity, conditions continued to improve
in the past week.

Twelve new sunspot groups emerged, two on April 18, three more on
April 19, five more on April 21, another on April 22 and one more on
April 24.

Average daily sunspot number jumped from 142.7 to 265.9, and average
daily solar flux from 177.4 to 216.

The Sun set another sunspot number record this week when the numbers
were 283, 283, 282 and 283 on April 21-24. The last time we saw a
higher daily sunspot number was 296 on April 17, 2014, 3,661 days
ago.

April 2014 was the peak of Solar Cycle 24.

Predicted solar flux over the next month shows values peaking at 215
from May 15-16 and again on May 19-20.

We see solar flux at 155, 145 and 135 on April 26-28, 130 on April
29 through May 2, 160 on May 3-6, then 165, 170, 180, 185, 190, 195,
200, and 210 on May 7-14, then 215 on May 15-16, 212 on May 17-18,
215 on May 19-20, then 200 and 190 on May 21-22, 170 on May 23-24,
165, 160 and 155 on May 25-27, then 160 on May 28 through June 2.

Predicted planetary A index is 15 on April 26-27, then 12, 10, 8 and
5 on April 28 through May 1, 10 on May 2-3, 5 on May 4, 8 on May
5-7, 5 on May 8-18, then 10, 15, 10 and 12 on May 19-22, 15 on May
23-24, 12, 8 and 7 on May 25-27, and 10 on May 28-30, 5 on May 31,
and 8 on June 1-3.

There is no report from OK1HH this week due to problems with the
Czech electric power grid.

Steve, NN4X wrote on April 26:

'The SFI and SSN have been very high lately, as you are more than
well aware.  Sadly, no F2 has been noted on 6m, but on the evening
of Wednesday, 4/24/2024 at around 10:00 pm ET.
 
'10m: Noted BY still being received here in EL98 FT8. Also, received
multiple decodes from CS7AUT in IM67!

'Not bad for 10:00pm!'

In another message, on the evening of April 25 he sent a long list
of 10 and 12 meter FT8 decodes at 11:42 PM EDT.

Signals from all over North America, plus Brazil, New Zealand,
Australia, Russia and China.

New report from Dr. Tamitha Skov, WX6SWW:

https://youtu.be/MIB_OnxhpLk

>From Weather.com, a cluster of sunspots:

https://bit.ly/3UAF9Wo

An article from The Sun about four flares:

https://bit.ly/3WftxJG

A Super Explosion about four flares:

https://bit.ly/3waYEeY

Send your tips, reports, observations, questions, and comments to
[email protected]. When reporting observations, don't forget to tell us
which mode you were operating.

For more information concerning shortwave radio propagation, see
www.arrl.org/propagation and the ARRL Technical Information
Service web page at, arrl.org/propagation-of-rf-signals . For
an explanation of numbers used in this bulletin, see
arrl.org/the-sun-the-earth-the-ionosphere .

An archive of past propagation bulletins is at
arrl.org/w1aw-bulletins-archive-propagation . More good
information and tutorials on propagation are at k9la.us/ .

Also, check this QST article about Solar Indices:

https://bit.ly/3Rc8Njt

Instructions for starting or ending email distribution of ARRL
bulletins are at arrl.org/bulletins .

Sunspot numbers for April 18 through 24 2024 were 247, 243, 240,
283, 283, 282, and 283 with a mean of 265.9. 10.7 cm flux was 226.9,
213.4, 209.5, 217.1, 226.8, 219.1, and 199.1, with a mean of 216.
Estimated planetary A indices were 4, 41, 12, 19, 9, 8, and 4, with
a mean of 13.9. Middle latitude A index was 5, 21, 10, 14, 10, 9,
and 4, with a mean of 10.4.