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ARRL Propagation Bulletin ARLP052 (2013)

ARLP052 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 52  ARLP052
From Tad Cook, K7RA
Seattle, WA  December 20, 2013
To all radio amateurs 

ARLP052 Propagation de K7RA

Geomagnetic conditions were more stable than expected last weekend,
good news for participants in the ARRL 10 Meter Contest.  The
planetary A index on Friday through Sunday was 3, 16 and 7 and
mid-latitude A index was just 3, 10 and 5.

Still, there were some scary moments, such as Saturday night in
North America (0035 UTC December 15) when the Australian Space
Forecast Centre issued this alert: "INCREASED GEOMAGNETIC ACTIVITY

For the reporting week, Thursday through Wednesday, average daily
sunspot numbers rose from 122.1 to 134.4, and average solar flux
went from 162.4 to 159.7, compared to the previous period, December

The latest prediction from USAF and NOAA has solar flux at 155, 150
and 145 on December 20-22, 140 on December 23-24, then 130 and 135
on December 25-26, 160 on December 27-28, 165 on December 29-31, 170
on January 1-2, 175 on January 3-6, 170 on January 7, then 165 on
January 8-10, 160 on January 11 and 150 on January 12-13. Solar flux
is expected to decline to a low of 135 on January 18-19, then rise
to 175 at the end of January.

This solar flux prediction for the next seven days was revised
downward significantly from yesterday's forecast in the ARRL Letter.
Wednesday's forecast for December 20-26 was 160, 155, 150, 150, 155,
150 and 155. The latest forecast (Thursday's) shows predicted flux
values of 155, 150, 145, 140, 140, 130 and 135 for those same seven
days. The downward revision was 5 points on December 20-22, 10
points on December 23, 15 points on December 24, and 20 points on
December 25-26.

The predicted planetary A index is 5 on December 20-24, 8 on
December 25-26, then  10 and 8 on December 27-28, 5 on December 29
through January 2, then 10 and 20 on January 3-4, 5 on January 5-9,
then 15 and 7 on January 10-11, then 5 after that until a more
active period around the end of January.

At you can get
a daily update of these forecasts, and lately the new one has been
issued between 2119-2123 UTC. But the December 11 forecast came out
at 0755 UTC on December 12, and the December 17 issue at 0051 UTC
December 18. In the past (for years now) I don't recall it ever
coming out as late as into the next UTC day.

F.K. Janda, OK1HH of the Czech Propagation Interest Group has a
shorter than usual geomagnetic forecast this week, perhaps for 12
days of Christmas. He sees quiet conditions December 20-24, mostly
quiet December 25, quiet to unsettled December 26, quiet to active
December 27, quiet on December 28, mostly quiet December 29, and
quiet again on December 30-31. Not the same twelve days as
Christmastide or Twelvetide, which actually extend into January, but
I thought it had a nice familiar ring to it.

Operators in the ARRL 10 Meter contest last weekend probably saw the
best conditions for this event in over a decade, and all the reports
sound very happy.

Larry Godek, W0OGH of Gilbert, Arizona did not participate this
year, but did tune around and listen. Larry reports, "It was
wonderfully busy. Signals all over the place and I'd think there
will be a lot of good scores reported. You could sure tell that the
band was good because the activity on other bands and modes was
waaayyyy down!  I'm really glad that the band was so good for this

Jeff Hartley, N8II of Shepherdstown, West Virginia reported:
"Conditions in this year's 10 meter contest were overall markedly
improved from 2012 when the SFI hovered just under 100. Last year I
made less than 10 total European QSOs, this year I worked 150 DLs,
61 Gs (not including the other British countries such as 14 GMs), 58
Is, and 52 Fs.

"The contest started without me, but at 0140Z there were still some
far western USA stations like AZ in and out and some fairly loud
deep South Americans in PY, LU, and CX on TE. The SAs were fairly
hard to work and one other local agreed. The Geminids provided some
good meteor scatter with active periods exceeding one minute and
some stations like K0TT in MN and W0AIH in WI audible almost all of
the time. Meteor scatter was also worked into most of New England
and a few 4s in KY, AL, and GA as well was 0s in MO and IA.

"The EU opening Saturday beat me out of bed with strong signals from
all over EU already in at 1240Z. Russians were not as loud as in Oct
and early November, but I managed to log quite a few in all areas of
Russian EU including UA4 and even two very western UA9s in the log.
Conditions were definitely above seasonal norms and the band stayed
open to OK/OM/9A/S5 probably at least 90 minutes longer than normal
probably due to some EU sporadic-E. Western EU also stayed in much
later than normal, truly exceptional. Throughout the contest
conditions to the south were very good allowing me to easily work
those stations with a Force 12 yagi with 2 el on 10 meters.
Conditions to CA were poor about 95-98 percent of the time when the
band could have been open with best conditions as the band opened
and again well past sunset when it closed. Skip was as short as
ND/SD/KS/TX with CO and the Rocky mountain states being in the sweet
spot for best propagation. AZ was the most active state from here
with 73 QSOs, 2nd was TX with 61, most worked on Sunday. My CO
contacts outnumbered CA 57 to 53, and UT equaled WA with 25.There
must have been some destructive solar wind (OH2XX was loud around
20Z) with a lack of KL7s and a late JA opening Saturday, but once 10
opened the JAs had fairly good signals and there was an amazingly
late secondary opening from about 0110 until past 0130Z when some
big guns could still be worked. I heard NH2T calling someone, but
only worked JA, UA0, and KL7 to the northwest Saturday evening.
Several eastern VKs had good signals and were easy to work thru
small pile-ups.

"Sunday conditions were pretty typical of an average mid winter day
with EU opening about 1235Z, but still some Russians were worked
with good conditions in the 13Z hour. A VU2 also called on CW with a
solid S7 signal. By 1615Z much of EU was gone completely and just
after 1700Z only Iberian peninsula stations (EA/CT) were left.

"Both days the solar activity was high enough to allow many
backscatter QSOs out to the edges of the skip zone, but the weak
spot was in 5 land. I never worked MS, worked LA only once, and a
couple of big gun AR stations were just readable. The best direction
was somewhat dependent on where the target station was beaming, but
south was the better choice until late in the day when SW and W took
over following the Sun. The JAs came in at a normal time around
2230Z with good signals and were fading but workable at 2330Z.

"Other than almost no sporadic-E and the frustration of missing many
west coast stations, conditions could not have been much better. The
highest scoring multi-op stations in the USA made over 3000 QSOs and
D4C had over 4600 with about 3 hours to go. Next year will probably
be way down from this 2nd peak of the cycle, but this current
upsurge was poorly predicted, so we will have to wait and see."

Dan Bates, N5TM of Katy, Texas reported, "Yes, 10 meters was insane.
Friday night was strange with band open until late after dark and
short hops into Colorado and Nebraska. EU was open early both
mornings with strong stations. Good openings the rest of the day to
SA and PNW.

"I could hardly find a clear spot to CQ. Settled in on 28.158 and
had nice runs."

Dan Eskenazi, K7SS of Seattle, Washington reported: "It was really
good! Super fun."

Howard Lester, N7SO of Schuylerville, New York commented, "I had a
lot of fun in the 10 meter contest. With the solar flux as high as
it was, in just maybe three hours over the course of the two days I
worked 27 countries, trying for one of each. Most were in Europe and
South America. My antenna is a 140 foot long inverted-V, so who
knows what directions it favors. The highlight was working club
station WY7SS in the little town of Sundance, Wyoming where, in 1969
during a cross-country trip, I stayed overnight and, at the local
gift shop, bought a leather belt with a longhorn buckle, and an
agate ring. I wish I still had them."

With an identical call sign suffix, Fred Glenn, K9SO of Palatine,
Illinois reported, "I only worked CW, but it was one of the best
'target rich' environments I've ever experienced on 10m. Reminded me
of a busy Field Day on 40 meters with signals all across the band at
maximum density. Both days saw great conditions into Europe and
Northern Africa in the mid morning fading to primarily domestic NA
and Caribbean by mid day and early afternoon. Later, we had big
signals from some of the big guns in ZL and VK land, and also from
Hawaii. Not much participation from those areas, at least on CW, so
the QSO point counts contributed from there were low. Virtually
nothing heard from Japan or South Africa on either day.

"I had put up a temporary dipole just for this event and was
rewarded with 35 new band-countries and a 37 state count with about
7 hours of 'point and shoot' operating.

"Long live the twin peaks!"

If you would like to make a comment or have a tip for our readers,
email the author at,

For more information concerning radio propagation, see the ARRL
Technical Information Service web page at For an explanation of the
numbers used in this bulletin, see An archive of past
propagation bulletins is at More good
information and tutorials on propagation are at

Monthly propagation charts between four USA regions and twelve
overseas locations are at

Instructions for starting or ending email distribution of ARRL
bulletins are at

Sunspot numbers for December 12 through 18 were 156, 141, 163, 158,
114, 91, and 118, with a mean of 134.4. 10.7 cm flux was 164.8,
163.1, 164.2, 156.2, 154.3, 159, and 156, with a mean of 159.7.
Estimated planetary A indices were 3, 3, 16, 7, 7, 3, and 4, with a
mean of 6.1. Estimated mid-latitude A indices were 2, 3, 10, 5, 5,
3, and 3, with a mean of 4.4.


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