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ARRL Propagation Bulletin ARLP004 (2023)

ARLP004 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 4  ARLP004
From Tad Cook, K7RA
Seattle, WA  January 27, 2023
To all radio amateurs 

ARLP004 Propagation de K7RA

From the first week of this year, we saw a dramatic and welcome
increase in solar activity, but it softened in this reporting week,
January 19-25.

Average daily sunspot numbers starting with the final reporting week
for 2022 were 96.1, 97, 135.9. 173.4 and 162.

Over the same period, average daily solar flux was 143.8, 157.8,
181.2, 221.8 and 198.9.

The northern hemisphere Winter Solstice was over a month ago, and
through the next two months we will see a gradual transition toward
Spring conditions.

Predicted solar flux over the next month shows values peaking near
205 on February 14-15, but flux values in the next few days are
lower than those posted in Thursday's ARRL Letter.

Predicted numbers are 150 on January 27-28, 145 on January 29-30,
140 on January 31 through February 1, then 145, 150 and a big jump
to 185 on February 2-4, 190 on February 5-6, 195 on February 7-12,
200 on February 13, 205 on February 14-15, 200 on February 16-18,
then 195, 200, and 190 on February 19-21, 185 on February 22-23, 180
on February 24-25, then 175 on February 26 through March 1, then
180, 185 and 190 on March 2-4. Flux values are expected to keep
rising, peaking above 200 again after March 10.

Predicted planetary A index, an indicator of geomagnetic instability
is 8 on January 27-28, 5 on January 29 through February 1, 12 and 8
on February 2-3, 5 on February 4-6, 12 on February 7-8, then 15, 12
and 5 on February 9-11, 8 on February 12-13, 5 on February 14-17,
then 8, 10, 10, 12 and 10 on February 18-22, 8 on February 23-25,
then 5 on February 26-27, then 15, 10 and 8 on February 28 through
March 2, and 5 on March 3-5, then 15 on March 6-8.

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
Ionosphere - January 26, 2023 from F.K. Janda, OK1HH.

"We had a week of increased solar activity with areas of sunspots
visible to the naked eye. These were AR3190 and AR3192. The ejected
CMEs produced auroras at higher latitudes. Since the geomagnetic
disturbances were mostly short-lived, they did not cause a
noticeable deterioration in shortwave propagation.

"A CME hit the Earth on 17 January at around 2200 UTC. At the same
time, it also hit the tail of comet ZTF (C/2022 E3) and broke it! A
piece of the tail of comet ZTF was chipped off and then carried away
by the solar wind.

"In recent days, AR3190 was the largest and most active, but even it
produced no more than moderately powerful flares. Both large
regions, AR3190 in the southwest and AR3192 in the northwest, are
beyond the edge of the solar disk by January 26. This is associated
with a significant drop in solar activity. While we know of other
active regions beyond the eastern limb of the solar disk, these are
not large enough to expect a repeat of the January pattern in
February. But we expect a similarly erratic pattern contributing to
limited forecasting capabilities."

Long time reader and contributor David Moore sends us this:

An article about Starspots:

KA3JAW is still having fun with 10 meter FM on 29.6 MHz.

On January 26 from 1430-1450 UTC he worked SV6EXH. With QSB, signals
were 3x3 to 5x5. Earlier on January 21 at 1646 UTC he worked DM5TS,
signals 4x5 with QSB.

Jon Jones, N0JK reported:

"Sunday morning (January 22, 2023) of the ARRL January VHF Contest
had some great propagation on the 6 meter band. I operated portable
signing W1AW/0 for VOTA. I was surprised when I turned on the radio
after setting up and the FT8 band map screen was full of strong
traces at 1505 UTC.

"There was a surprise sporadic-E opening Sunday morning to W1, W2,
W3, VE3, and W8. The Ontario stations were booming in and I had a
pileup calling. Even some F2 with PJ4MM in FK52 peaking at -8 dB at
1554 UTC.

"Even more amazing MM0AMW decoded several W9 stations on 6 meters.
Several stations I worked, such as KW9A were spotted into Scotland.
Unsure if the propagation mode was multi-hop Es or F2?

"Later that evening an Es -- TEP opening from the northeast states
to South America."

More dramatic solar warnings.

Here is a prediction that was WAY off:

Space Weather Woman Dr. Tamitha Skov, WX6SWW, has a new video:

This weekend is the CQ World-Wide 160-Meter CW contest.

Check for details.

Send your tips, reports, observations, questions and comments to

For more information concerning shortwave 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 January 19 through 25, 2023 were 166, 197, 194, 166,
144, 127, and 140, with a mean of 162. 10.7 cm flux was 226.1,
217.5, 208.7, 198.6, 189.1, 180.2, and 171.8, with a mean of 198.9.
Estimated planetary A indices were 7, 6, 17, 9, 7, 4, and 7, with a
mean of 8.1. Middle latitude A index was 6, 4, 11, 7, 5, 3, and 5,
with a mean of 5.9.


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