Register Account

Login Help

ARRL Propagation Bulletin ARLP050 (2012)

ARLP050 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 50  ARLP050
From Tad Cook, K7RA
Seattle, WA  December 14, 2012
To all radio amateurs 

ARLP050 Propagation de K7RA

Average daily sunspot numbers fell 13.5 points this week from 61.1
to 47.6. Average daily solar flux was about the same this week as
last, rising 1.1 points to 102.7. Geomagnetic indices were even
quieter this week than last.

Predicted solar flux is 115 on December 14, 120 on December 15-16,
115 on December 17-19, 110 on December 20-21, 115 on December 22-23,
110 on December 24-27, 100 on December 28-29, 95 on December 30
through January 3, 100 on January 4-5, and 105 on January 6-8. Solar
flux then jumps abruptly to 125 and 130 on January 13-14.

The predicted planetary A index is 5 on December 14-15, 8 on
December 16, 10 on December 17, 5 on December 18-28, 8 on December
29, 5 on December 30 through January 5, 7 on January 6-7, 5 on
January 8-9, 8 on January 10-11 and 5 on January 12-27.

OK1HH predicts the geomagnetic field will be quiet to unsettled on
January 14, mostly quiet December 15, quiet to unsettled December
16, active to disturbed December 17, mostly quiet December 18, quiet
December 19. A positive storm phase is expected December 20, with
active to disturbed conditions December 20-21, quiet to unsettled
December 22, mostly quiet December 23, quiet December 24, quiet to
unsettled December 25, mostly quiet December 26, quiet December 27,
quiet to active December 28, quiet December 29, quiet to unsettled
December 30-31, quiet January 1-4, active to disturbed January 5-6.

Both NASA and NOAA have tweaked their predictions for the peak of
the current solar cycle next year. To see the NOAA changes, go to and select PRF 1940 and go to page
12. Then open another browser window and select PRF 1944 and go to
page 16.

Notice that in the November prediction, the cycle peaks at 90 in May
through July 2013, and the smoothed sunspot number for January
through April is 81, 83, 85 and 88. In the December prediction, we
see two instead of three peak months, June and July 2013. The
numbers for January through May are 79, 81, 83, 86 and 88. This is a
marginally weaker predicted peak for cycle 24.

The latest NASA prediction is at

The change here is from 73 to 72 for a smoothed sunspot number
maximum in the December 10 prediction compared to the November 2
prediction. The other change is last month when they wrote "The
smoothed sunspot number (for 2012/02) is already nearly 67 due to
the strong peak in late 2011 so the official maximum will be at
least this high." This month the end of the line was changed to "at
least this high and this late."

Seen on Bob Kile's (W7RH) Facebook page on Tuesday: "For those low
band operators out there. The solar activity remains low and the
solar wind is under 300km/sec. That means West Coast to EU, boys! I
have six in the log last Saturday night and there have been West
Coast openings since last Friday."

I believe Bob is referring to 160 meters.

Lloyd Berg, N9LB of Oregon, Wisconsin (Oregon is a town just south
of Madison, Wisconsin) wrote about the 10 Meter contest:

"This year required a continuous effort on Friday evening, all day
Saturday and all day Sunday, including numerous 'dead band' times of
waiting and wondering if the band was going to come back or not. I
can see a large chunk of the band on my FLEX - Software Defined
Radio panoramic display - and when I say the band went dead, I see
it happening just like somebody turned down the RF gain - only took
a minute or two to extinguish all signals. I'd actually transmit
just to make sure the antenna was connected. I also looked out the
window many times to see if the antenna was still there (it was).
Really odd.

"At the beginning of the contest, the solar numbers looked awfully
low for decent 10m propagation: SFI=97, SSN=23, A=1, K=0. Conditions
were very weird from my Wisconsin QTH. The band kept going dead,
then we'd have a bit of garden variety E-skip 'here-and-there,' then
dead again. Then it would open up real wide, going way beyond simple
E-skip... North, South, East and West all at the same time.

"Worked everything East of the Mississippi in North America
(E-skip). Worked Hawaii, more Alaskans than in any other single
contest ever, many BC, and a NWT, but never heard most of the Rocky
Mountain states. Easy to work every active station in South and
Central America, and the Caribbean - day or night. Nice and strong
but short-lived openings to Azores, Cape Verde and Canary Islands.

"Worked several ZSs, VKs, ZLs and an E51 during a few short precious
minutes of openings on Saturday evening and again on Sunday
afternoon. No Japan or Asia heard at all. Only European contacts
were a couple of Spain and Portugal, again during a very brief
opening (well after their sunset)."

Thanks, Lloyd!

Jeff Hartley, N8II of West Virginia wrote, also about the 10 Meter
contest: "Sunday was noticeably better than Saturday in the 10M
contest this past weekend. I only worked about 15 EU stations all
weekend, but conditions to the west coast were extremely good and we
had plenty of Es Friday night and Saturday night into MN, WI, SD,
IA, MO, KS, and OK as well ME and VE1, VE9, VY2. The last hour
featured Es into KP4 and NC, SC, AL, KY, TN, FL, MS, AR, LA and TX.

"Highlights were working A45 around 1630Z Saturday and a great long
path Asian opening on Sunday which lasted for hours, starting around
1250Z on CW with about four JAs, BD7 at 1302Z, BV1 at 1308, XV1 at
1405, HS0 at 1414,and 9V1 at 1538, and also called on phone by HS0
at 1506. Sunday was extremely good to the west coast from 1710Z thru
2235Z, one WA station running a half watt was a solid S4 and mobiles
had solid signals. All states were worked on CW and only missed AK
on phone. There was propagation of some sort to all states at one
time or another with only the very close states on backscatter

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 Find more good
information and tutorials on propagation 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 6 through 12 were 49, 23, 35, 40, 49,
55, and 82, with a mean of 47.6. 10.7 cm flux was 97.4, 97.1, 101.1,
103.7, 104, 103.7, and 111.9, with a mean of 102.7. Estimated
planetary A indices were 1, 1, 1, 4, 3, 2, and 2, with a mean of 2.
Estimated mid-latitude A indices were 2, 1, 1, 3, 3, 2 and 3, with a
mean of 2.1.


Instragram     Facebook     Twitter     YouTube     LinkedIn