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ARRL Propagation Bulletin ARLP004 (2024)

ARLP004 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 4  ARLP004
From Tad Cook, K7RA
Seattle, WA  January 26, 2024
To all radio amateurs 

ARLP004 Propagation de K7RA

Just four new sunspot groups emerged this reporting week, January
18-24, one on each day, January 18-21.

But it looks like we may see flares, CMEs and geomagnetic storms
over the next few days. identified sunspot group 
AR3561 as "hyperactive."

Sunspot numbers and solar flux declined, and geomagnetic indicators
rose, but only slightly.

Average daily sunspot number dropped from 167.3 to 130.6, and
average solar flux from 184.1 to 173.3.

Average planetary A index rose from 5 to 7.4, and middle latitude
numbers from 3.9 to 5.1.

Looking ahead, we may see a short term peak in solar flux centered
around February 11, and another about six weeks from now.

Predicted solar flux is 160 on January 26-27, 150 on January 28 to
February 1, 170 on February 2, 175 on February 3-4, 180 on February
5-8, then 190, 190 and 195 on February 9-11, then 190 and 185 on
February 12-13, 180 on February 14-15, then 175. 170, 175, 175, 170,
175, and 170 on February 16-22, then 165, 160, 165, 160 and 165 on
February 23-27, 170 on February 28-29, and 175 on March 1-2, then
180 on March 3-6.

Predicted planetary A index is 25, 30, 18, 10 and 8 on January
26-30, then 5 on January 31 through February 16, and 8 on February
17-18, then 5 on February 19-24, then 10, 12 and 10 on February
25-27, and 5 on February 28 through early March.

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
Ionosphere - January 25, 2024, from OK1HH:

"At the present stage of the 11-year solar cycle, there are five to
thirteen groups of spots (or active regions) on the Sun. In three of
them, we can observe such magnetic configuration that allows the
development of a larger flare, possibly with a CME.

"On the other hand, there are relatively few coronal holes on the
Sun, reducing the likelihood of Earth being hit by an enhanced solar
wind and then geomagnetic disturbances. Therefore, the evolution is
quieter, and the level of shortwave propagation is a little calmer
than we might otherwise expect."

Glenn Packard, K4ZOT reported from Atlanta, Georgia on January 22
that he worked New Zealand on 6 meter FT8 at 0257 UTC:

"I just happened to tune to 6M tonight after being disappointed on
6M for the Winter season.  Then Bloom, ZL4TT, comes through at R-19
and me at -08.  Just WOW.  Called once and he came right back to me.
Band then went dead after the contact.  Amateur Radio still has
surprised this Olde Man."

Solar Cycle 25 nearing its peak?

Articles about recent Solar activity:

A NOAA article about Solar Cycle Progression:

The latest report from Dr. Tamitha Skov, WX6SWW, for January 22:

Did you know she has about 84,500 subscribers?

New, long program from Dr. Skov for January 25:

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

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 .

Also, check this QST article about Solar Indices:

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

Sunspot numbers for January 18 through 24 2024 were 113, 137, 144,
150, 139, 123, and 108, with a mean of 130.6. 10.7 cm flux was
162.3, 157.4, 166.3, 178.5, 196.1, 180.3, and 172, with a mean of
173.3. Estimated planetary A indices were 6, 8, 6, 6, 9, 7, and 10,
with a mean of 7.4. Middle latitude A index was 4, 5, 4, 5, 6, 5,
and 7, with a mean of 5.1.


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