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ARRL Propagation Bulletin ARLP002 (2023)

ARLP002 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 2  ARLP002
From Tad Cook, K7RA
Seattle, WA  January 13, 2023
To all radio amateurs 

ARLP002 Propagation de K7RA

Wow! Sunspot numbers up, geomagnetic disturbances down. What could
be better? Okay, maybe Solar Cycle 19, but that was 66 years ago and
by far the all time largest.

But this is now, we are in Solar Cycle 25, and this sunspot cycle is
emerging better than the consensus forecast. It is predicted to peak
about 30 months from now in Summer 2025.

Solar cycles tend to ramp up faster than they decline, so we look
forward to great HF propagation for years to come.

There were six new emerging sunspot groups in our reporting week,
January 5-11. The first two appeared January 5, the next on January
8, another on January 9  two more January 10 and still another on
January 12, when the sunspot number was 151.

Average daily sunspot number rose from 97 to 135.9, and average
daily solar flux from 157.8 to 181.2, compared to the previous seven

On Thursday, January 12 the noon solar flux was huge, 211.6, far
above the 181.2 average for the previous week.

Average daily planetary A index declined from 15.4 to 6.7, and
middle latitude A index from 10.9 to 6.1.

Compare the solar numbers to last year. A year ago in Propagation
Forecast Bulletin ARLP002 the average daily sunspot number was only
42.4 (135.9 now) and average daily solar flux was 101.6 (181.2 now).
10 and 12 meters now have openings every day.

The solar flux prediction was revised dramatically upward between
the Wednesday numbers in Thursday's ARRL Letter and the Thursday
numbers in this bulletin, from 196 to 210 for January 13.

Predicted solar flux is 210 on January 13 and 14, then 208, 206 and
204 on January 15-17, 200 on January 18-19, then 180, 160, 130 and
135 on January 20-23, 140 on January 24-26, 145 on January 27, then
155, 155 and 160 on January 28-30, 170 on January 31 through
February 2, 175 and 180 on February 3-4, 185 on February 5-6, then
180, 178 and 175 on February 7-9, 155 on February 10-12, 145 on
February 13, 140 on February 14-16, 130 on February 17-18 and
increasing to 160 by the end of the month.

Predicted planetary A index is 5, 10, and 8 on January 13-15, 5 on
January 16-17, then 10, 8, 10 and 8 on January 18-21, 5 on January
22-24, then 8, 22, 12 and 8 on January 25-28, 5 on January 29-31,
then 12 and 8 on February 1-2, 5 on February 3-5, then 10, 12 and 8
on February 6-8, 5 on February 9-13, then 8, 15, 10 and 7 on
February 14-17, and 5 on February 18-20.

Jon Jones, N0JK wrote:

"There was a 6 meter F2 opening between Ecuador and North America
January 6, 2023 around 1530 UTC, mostly between the Southeast United
States and Ecuador. Solar Flux was 172.4.

"Later there was some weak sporadic-E on 6 Meters. I logged W4IMD
(EM84) at 1942 UTC and W7JW (EN82) on 6 meter FT8 via Es at 1954 UTC
January 6.

"High Solar Activity this week."

N0JK writes "The World Above 50 MHz" column in QST.

OK1HH wrote:

"Large sunspot groups on the Sun's far side, detected by
helioseismology after the beginning of this year, showed that the
region of active heliographic longitude, gradually approached the
eastern limb of the solar disk. Solar activity increased after their
arrival. Solar flux rose from 146 on January 2 to 195 on January 11.
Yet one solar revolution back (December 15) it was only 166 and two
turns back (November 18) only 116.

"The January 6 prediction of increasing activity was brilliantly
confirmed, especially by a large X-class flare in AR3182 with a
maximum at 0057 UTC.

Surprisingly, it did not produce a CME - the ejected particles never
left the Sun.

"In the following days AR3182 activity was joined by the newly
erupted AR3184, again in the southeast of the solar disk. An X-class
flare was observed there as well (X1.9 on January 9 at 1850 UTC).

"Since most of the large flares in the last few days occurred when
it was nighttime in Europe, blackouts up to 30 MHz were recorded,
especially by stations in and around the Pacific. It was not until
the eruption on January 9 at 1850 UTC that a shortwave blackout was
seen in the western Atlantic, including east coast of the U.S. On
January 10, the Sun produced another X-class eruption, from new
sunspot group AR3186.

"As active regions approach the central meridian, the probability of
Earth being hit by particles from possible CMEs increases, or more
importantly the Earth's magnetic field activity increases, MUF
levels decrease, and the evolution of shortwave propagation
conditions gradually somewhat worsens during disturbances that are
difficult to predict accurately."

Mike Schaffer, KA3JAW in Pennsylvania (FN20jq) reported, "On
Thursday, January 12, 29.6 MHz FM went active with 3-hop sporadic-E
transatlantic propagation to England, Spain from 1346 thru 1600 UTC,
then to single hop Es to Puerto Rico at 1813 UTC.

"Readability ranged from (1) unreadable to (4) practically no
difficulty, Strength ranged from (1) faint - signals barely
perceptible to (5) fairly good signals. All signals had deep QSB.

"Time UTC:    Callsign:   Grid:    Miles
1346         G3YPZ       JO02bs   3,494
1354,1528    G4RIE       IO83rn   3,372
1413,1521    2E0PLO      IO91wm   3,511
1600         EA2CCG      IN92ao   3,660
1813         KP4NVX      FK68vl   1,625"

Here is a photo of the Sun:

One of a Solar flare:

Solar news in the Washington Post:

An article on Radio blackouts:

The Parker Solar Probe:

The latest from Dr. Tamitha Skov, WX6SWW:

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 5 through 11, 2023 were 103, 101, 104, 117,
142, 201, and 183, with a mean of 135.9. 10.7 cm flux was 154.3,
172.4, 178.9, 183.8, 190.9, 193, and 195.1, with a mean of 181.2.
Estimated planetary A indices were 8, 4, 6, 8, 5, 7, and 9, with a
mean of 6.7. Middle latitude A index was 6, 4, 5, 7, 7, 6, and 8,
with a mean of 6.1.


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