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ARRL Propagation Bulletin ARLP035 (2022)

ARLP035 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 35  ARLP035
From Tad Cook, K7RA
Seattle, WA  September 2, 2022
To all radio amateurs 

ARLP035 Propagation de K7RA

The past week saw many interesting events. The DRAO observatory at
Penticton, British Columbia (the source of 10.7 cm solar flux
measurements) was overwhelmed by solar flares, and at 2000 UTC on
August 28 reported a solar flux value of 251.9, and the next day at
1700 UTC, a value of 357.1.

The 2000 UTC local noon numbers are the official solar flux number
for each day, so for the August 28 value I chose to report the 2300
UTC number of 133.5 instead.

I checked with astronomer Andrew Gray at Penticton, and he reported,
"The high values are indeed because of solar activity, both
yesterday and today flares occurred right during our flux

Solar activity increased this reporting week (August 25-31) with
average daily sunspot numbers rising from 58.7 to 74.9 and solar
flux from 104.5 to 123.8.

Without that correction for August 28, average daily solar flux
would have been 140.8 instead of 123.8.

I have seen these errors in the past, but they are rare. When they
occur, there is only 1/3 chance they will happen during the daily
2000 UTC reading, which sends them into the official daily solar
flux data.

Note that NOAA did not correct the high false value:

Average daily A index was a little lower, the planetary values
shifting from 12.6 to 10.1 and middle latitude from 11 to 9.4.

Three new sunspot groups appeared on August 25 at the beginning of
the reporting week, but none until September 1, with two new sunspot
groups. The daily sunspot number rose from 42 on Wednesday to 67 on

Total sunspot area peaked on August 27.

Predicted solar flux is more optimistic in the Thursday night
version, as opposed to the Wednesday forecast reported in the ARRL

Instead of 110 on September 2, the latest forecast is 116, 118 and
118 on September 2-4, 115 on September 5, 110 on September 6-8, then
118, 124, 130 and 128 on September 9-12, then 120, 117, 105 and 102
on September 13-16, then 98 on September 17-18, then 104, 102 and
108 on September 19-21, 118 on September 22-23, 124 and 125 on
September 24-25, 120 on September 26-28, 115 on September 29 to
October 1, then 112 on October 2, 108 on October 3-4, then 115, 120,
124 and 130 on October 5-8.

Flux values may briefly dip below 100 in mid-October.

Predicted planetary A index is 10, 15, 30, 25 and 15 on September
2-6, 10 on September 7-8, 12 and 8 on September 9-10, 5 on September
11-12, then 12, 15 and 10 on September 13-15, 8 on September 16-17,
5 on September 18-23, then 14, 10 and 8 on September 24-26, 5 on
September 27-29, then 30, 38, 20, 15, 18, 10, 12 and 8 on September
30 through October 7, and 5 on October 8-9.

At 0209 UTC on September 2 the Australian Space Weather Forecasting
Centre issued a geomagnetic disturbance warning:  "Disturbed
conditions caused by a high speed wind stream in a geoeffective
direction are expected September 3-5."

Frantislav K. Janda, OK1HH shares his weekly commentary:

"The recent rise in solar activity, especially during August 27-30,
was triggered by two sunspot groups, AR3088, which on 29 August fell
behind the western limb of the solar disk, and AR3089, which on 30
August passed through the central meridian, so entered the region of
the so-called present active longitudes.

"Both sunspot groups are in the southern hemisphere of the Sun,
while in both were daily registered flares of moderate magnitude.
CMEs have been registered in four cases. Given the proximity of the
coronal hole, we would expect a significant increase in geomagnetic
activity, but only at first approach.

"However, there was only a slight increase in geomagnetic activity,
confirming the current solar wind path models. We expect it to
intensify and then increase in geomagnetic activity since about
September 4 onwards. A further gradual increase in total solar
activity can be expected a few days later."

I (K7RA) noticed some curious 12 meter propagation, testing the band
using FT8 on This way I can
see instantly where my signal is heard, and get accurate, objective
signal reports.

On August 31 at 2038-2116 UTC my calls were heard nowhere in North
America outside my local area, which were stations 4-54 miles away.
But all stations hearing me were in a straight line running through
Mexico and Central America, then down to Brazil.

XE1GLL, XE1EE, and XE1AQY, down to V31MA, LU6FL and PU3MSR. No 12
meter resonant antenna, just a 32 foot end-fed indoor wire fed with
a 4:1 UnUn transformer and automatic antenna tuner.

Other curious 12 meter behavior was on Saturday, August 27 at 2252
UTC when the only stations hearing me (FT8 again) were ZL2OK at
7,120 miles with a strong signal report of +4 dB and WH6FXV at 2,649

Ten minutes later at 2302 UTC JA1QGI was the only station reporting,
from 4,746 miles away. Four minutes later JN4MIV reported. At 2312
UTC ZL2OK was back, this time reporting -4 dB, 8 dB lower than the
earlier report.

At 2315 UTC I worked JH6RKI and copied several more Japanese

Newsweek Magazine has been reporting interesting solar news

And Forbes.

Is "The Independent" one of the UK Fleet Street tabloids? Perhaps a
RSGB member could inform us.

Another wonderful report from Dr. Tamitha Skov, WX6SWW, ham radio's
own Space Weather Woman:

In the following links, many are presented for your amusement only.
I do not believe that a huge solar flare will ever engulf the Earth.

A canyon of fire:

EarthSky reports (page down):

A report four weeks old, but still relevant:

Growing sunspot a threat:

Our angry Sun:

This one is a bit over the top:

From a few days ago:

Radio blackouts:

Flares and blackouts:

More Flares:

Existential threat:

Flare facing Earth:

Sunspot somehow destroys Earth:

The 61st annual All Asian DX Phone contest is this weekend.
Information can be found here:

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 for August 25 through 31, 2022 were 94, 88, 84, 79,
87, 50, and 42, with a mean of 74.9. 10.7 cm flux was 117.8, 118.6,
127.5, 133.5, 130.6, 125.6, and 113.3, with a mean of 123.8.
Estimated planetary A indices were 5, 5, 14, 7, 14, 13, and 13, with
a mean of 10.1. Middle latitude A index was 5, 5, 11, 7, 13, 13, and
12, with a mean of 9.4.


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