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ARLP007 Propagation de K7RA

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Feb 16, 2024, 10:29:48 AMFeb 16
ARLP007 Propagation de K7RA

Propagation Forecast Bulletin 7 ARLP007
>From Tad Cook, K7RA
Seattle, WA February 16, 2024
To all radio amateurs

ARLP007 Propagation de K7RA

Seven new sunspot groups appeared over the past week, February 8-14,
two on February 8, three on February 10, and two more on February 13
and 14.

Then on February 15 three more sunspots emerged.

Now this is a personal opinion, but from recent numbers I suspect
that we may at the peak of Solar Cycle 25 or just prior to the peak.
We won't know when the actual peak occurred until six months after.

Average daily sunspot number declined from 142.3 to 134.6, but
average daily solar flux increased from 165.5 to 190.

I don't know why the solar numbers were so seemingly out of whack,
but average daily sunspot number declined as average daily solar
flux rose, by a lot.

Average daily planetary A index rose from 5.1 to 7.4, while middle
latitude numbers from 4.4 to 6.1.

The most active day was February 11 with planetary A index rising to
15, but that is hardly stormy. This was caused by an unexpected CME
impact at 0211 UTC according to

So, what is the outlook for the next few weeks?

Concerning solar flux, it seems we are currently in the midst of a
peak over the next few days at 185 and 182 on February 15-16, then
another short term peak at 170 on March 3-10.

On February 17-23 the forecast sees the flux at 175, 172, 170, 165,
175, 165 and 160, then 150 on February 24-28, then 155, 160 and 165
on February 29 through March 2, then 170 on March 3-10, 165 on March
11-3, 170 on March 14, 160 on March 15-19, then 162, 165 and 160 on
March 20-22.

Predicted planetary A index is 5 on February 16-18, 8 on February
19, 5 on February 20-25, then 8 and 7 on February 26-27, then 5 on
February 28 through March 23.

This is the same data that appeared in the ARRL Letter on Thursday,
which was the report from February 14.

Unfortunately, NOAA did not post the updated forecast on Thursday.
Thursday evening, I phoned the NOAA forecast desk, and they didn't
have the data from US Air Force. I then phoned the 557 Weather Wing
at Offutt Air Force Base and was told they had a major network
outage Thursday afternoon, and the data may be lost.

Fortunately, the phone numbers at both locations are answered 24-7.

If you need an updated forecast, check:

It is normally updated every day after 2200 UTC.

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
Ionosphere - February 15, 2024 from OK1HH:

"Over the past week, we saw the transition of two large active
regions with complex magnetic configurations on the solar disk:
AR3575 followed by AR3576, which will be at the western limb of the
disk on February 16.

"More massive flares, including proton flares accompanied by CME
were observed in both regions. Protons from the flares bombarded the
Earth's atmosphere for most of the days. CMEs, however, hit the
Earth with little or no impact. This included a strong X3.4 class
solar flare followed by a S2 class radiation storm on 9th February.
Energetic solar protons impacted the upper layers of the Earth's
atmosphere and caused mainly polar cap absorption (PCA). This
significantly increased the attenuation of radio signals at high

"We could also guess whether the CMEs were just delayed since the
eruptions of 9 and 10 February and would not arrive until 13
February, or whether they would miss the Earth. NASA guessed that
they would arrive. But the correct answer was they missed, which was
confirmed by the more or less calm development on 14 February.

"After the sunset of the two large active regions AR3575 and AR3576,
solar activity will decrease. However, helioseismological
observations indicate the presence of active regions on the far side
of the Sun. After their ascent to the solar disk, solar activity
will increase again since early March. Solar activity should be
highest between March 3 and 10. Meanwhile, geomagnetic activity
should continue to be low. Therefore, we expect an improvement in
shortwave propagation conditions.

"F.K. Janda, A.R.S. OK1HH, "

This weekend is the CW portion of the ARRL International DX contest.
Details can be found at:

Two articles about a CME and flares:

Three days of sunspots:

Multiple pictures of Sunspot region 13585:

Bob, KB1DK, from Connecticut wrote:

"During the last two weeks, activity on 10 meter SSB was bustling,
and included many POTA, SOTA, and mobile stations in Europe. In
fact, I heard Europeans on 12 meters saying they moved to that band
because 10 became so busy. Propagation on 10 has been very good from
southern New England, resulting in multiple QSOs with India and New
Zealand. QSOs with the middle east are almost routine now.

"My occasional fixed mobile operating has been extremely productive
and satisfying. I strongly recommend taking advantage of these great
conditions on 10 meters while we have them."

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 February 8 through 14 2024 were 149, 105, 146,
144, 153, 122, and 123, with a mean of 134.6. 10.7 cm flux was 185,
183.4, 193.8, 180.4, 208.3, 194.8, and 184.1, with a mean of 190.
Estimated planetary A indices were 5, 6, 5, 15, 4, 10, and 7, with a
mean of 7.4. Middle latitude A index was 5, 4, 4, 12, 4, 8, and 6,
with a mean of 6.1.

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