SB PROP @ ARL $ARLP004
ARLP004 Propagation de K7RA
QST de W1AW
Propagation Forecast Bulletin 4 ARLP004
>From Tad Cook, K7RA
Seattle, WA January 25, 2013
To all radio amateurs
SB PROP ARL ARLP004
ARLP004 Propagation de K7RA
Average daily sunspot numbers over the past week were less than half
the value for the previous week, dropping nearly 73 points to 56.4.
Average daily solar flux declined as well, nearly 47 points to
110.7. Average geomagnetic indices were up about 50%, but still very
quiet. The higher average was due to events on January 17, when the
planetary A index was 13, higher than recent measures, but still
moderate. The cause of the mild disturbance was the arrival of a
CME, or Coronal Mass Ejection.
Predicted solar flux from the January 24 forecast from NOAA and USAF
has 10.7 cm flux values at 100 on January 25-26, 95 on January
27-30, 100 on January 31 through February 1, 110 on February 2, 120
on February 3-4, 125 on February 5-8, 120 on February 9-14, 115 and
110 on February 15-16, and 105 on February 17-18.
It doesn't look like a return to solar flux values around 170 (where
it was on January 9-12) is expected any time soon. But those high
levels earlier in the month weren't predicted either.
Looking back, a flux reading of 135 was predicted for January 9 in
the November 25 through December 9 daily forecasts, then downgraded
to 110 on December 10-16, then increased to 115 on December 17-30,
downgraded to 105 on December 31 through January 2, increased to 115
on January 3, 135 on January 4, 130 on January 5-6, 145 on January
7, and 150 on January 8. The final result? 169.3 on January 9, far
above any predictions over the previous 45 days, which were revised
The forecasts are issued daily, usually after 2100 UTC and posted at
The predicted planetary A index from the same January 24 forecast is
8, 15, 20 and 12 on January 25-28, 5 on January 29 through February
8, 8 on February 9-10, 5 on February 11-18 and 8 on February 19. The
January 25-28 levels are higher then predicted a day earlier, on
January 23. In that earlier forecast, planetary A index for those
same four days was 8, 8, 5 and 5.
F.K. Janda, OK1HH of the Czech Republic expects the geomagnetic
field will be quiet to unsettled on January 25-26, quiet January
27-28, mostly quiet January 29, quiet on January 30-31, mostly quiet
February 1-2, quiet on February 3, mostly quiet February 4, quiet on
February 5-6, quiet to unsettled February 7-8, quiet to active
February 9-10, mostly quiet February 11-12, quiet to active February
13-14, active to disturbed on February 15, and quiet to unsettled
Jeff Hartley, N8II of Shepherdstown, West Virginia wrote, "It has
been a pretty boring winter for DX. I did work four VK3s in a row
from 2225-2255Z including one mobile who was S6 and a QRP 5 W to 1/2
wave vertical who was S5 with QSB on 20M SSB long path Thursday
(January 24), so that path was very good. 12 and 10 seemed dead at
that time and only South America was heard on 15. No European
signals were heard on 160 around then and again at 0050Z (nothing on
80 also at 0050Z). But, if the K stays low, the lower flux should
help the CQWW 160 contest this weekend."
Unfortunately, the forecast for this weekend has some geomagnetic
activity, with the planetary A index on February 25-27 at 8, 15 and
The 160 meter contest Jeff referred to is the CW weekend of the CQ
World Wide 160-Meter Contest. The contest page at
http://www.cq160.com/) says it runs from 2200 GMT today (Friday,
January 25) to 2200 GMT Sunday. By the way, 2200 GMT (Greenwich
Mean Time) for our purposes is the same as 2200Z or 2200 UTC. On the
West Coast, this is long before sunset, at 2:00 PM PST.
On January 19, Jeff wrote: "Friday morning January 18 I had a chance
to operate and had some very strong signals on 10 phone from the UK
with small stations mostly S7-9. Even 5 and 10 watt stations were
good copy. This was starting about 1330Z and the EU opening ended
after 1600Z. Countries worked in EU started with SP, DL, EI, G, GM
then later PA, ON, F and the DLs were about the only ones left at
1610Z. Friday evening was noticeably better than all this past week,
but did not get to the radio until 0040Z. At that time 15 was in
good shape to JA with the loudest, JH1GEX S9. BW2AK was heard and
9V1YC who was about S3-4 was worked easily thru a pile up. 15 was
still open to JA at 0115Z, normally by 24Z, 15 seems closed to
everywhere. 17 was also quite good into JA around 0100-0130Z with
JA9YYY S9 on SSB.
The HA DX contest started at 12Z Saturday with lots of EU and
Russian activity. Russians are usually only easy to work very early
in the day on 20 and about nil on 15 and higher. At 1315Z when I
started thru 1430Z, Russians had good signals on 20 CW but there was
deep rapid QSB making copying dits and sometimes whole
letters/numbers very difficult. I worked about three Ural mountain
area UA9s and found UN2E about S3 plus quite a few from UA3, about
four from UA4 and some loud ones near St Petersburg from UA1. The
deep QSB was even a problem on signals as close as Germany as well
as the Hungarians. YE1ZAT called in around 1545Z with a good signal.
15 was open pretty well to EU, but 10 was barely open at all to very
southern EU, I heard T77BL working AA3B.
"In the afternoon, I briefly operated in the NAQP phone contest
before heading off to work. At 1835-1900Z, 10M had a good number of
loud signals with one VE6 hitting 30 dB over S9. Many UT stations
were worked along with stations from CO, AZ, WA, ID, MT and NM; only
W6TA and K6LA who was weak were worked in CA. 15 was wide open to TX
and was a bit of a struggle to work west coast stations with Midwest
stations beating me out consistently."
In a January 18 email titled "Outstanding 160M propagation Jan 11-12
in Ohio," Robert Elek, W3HKK of Johnstown, Ohio wrote: "Worked more
Europeans than ever around their sunrise on Jan 11 and 12, plus KL7
and VP2 earlier in the night. Huge signals! Received my first 599
reports from Europe (two of them!) as well as two SWL cards from
Russia for that activity. The rig: 100w to quarter wave 40 ft
vertical inverted L with 22x65 ft radials.)
"I was excited for the weekend conditions but Jan 13-14-15 turned
out to be stinko for DX. Amazing how things change on Top Band.
Gotta get 'em while you can."
Don't miss "The Penticton Solar Flux Receiver," an article on pages
39-46 in the February 2013 issue of QST. This gives a great
explanation about where the solar flux numbers in our bulletin
originate. It answered questions I had about the process, such as
how they handle readings that go off the scale during a space
If you would like to make a comment or have a tip for our readers,
email the author at, k...@arrl.net.
For more information concerning radio propagation, see the ARRL
Technical Information Service web page at
http://arrl.org/propagation-of-rf-signals. For an explanation of the
numbers used in this bulletin, see
http://arrl.org/the-sun-the-earth-the-ionosphere. An archive of past
propagation bulletins is at
http://arrl.org/w1aw-bulletins-archive-propagation. Find more good
information and tutorials on propagation at
Monthly propagation charts between four USA regions and twelve
overseas locations are at http://arrl.org/propagation.
Instructions for starting or ending email distribution of ARRL
bulletins are at http://arrl.org/bulletins.
Sunspot numbers for January 17 through 23 were 74, 56, 46, 48, 50,
53, and 68, with a mean of 56.4. 10.7 cm flux was 122.7, 115.2,
106.7, 106.6, 108.3, 110.3, and 104.9, with a mean of 110.7.
Estimated planetary A indices were 13, 9, 7, 9, 4, 1, and 1, with a
mean of 6.3. Estimated mid-latitude A indices were 12, 7, 9, 8, 4,
1, and 1, with a mean of 6.
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