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ARRL Propagation Bulletin ARLP053 (2005)

ARLP053 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 53  ARLP053
From Tad Cook, K7RA
Seattle, WA  December 16, 2005
To all radio amateurs 

ARLP053 Propagation de K7RA

This is Propagation Forecast Bulletin number 53 for the year, which
isn't bad, since 2005 is only 50 weeks old. We sometimes put an
extra one out on Sunday night when a holiday forces an early
bulletin, or if the early one is too soon for the weekly solar
numbers, which are reported for Thursday through Wednesday.

Last weekend's ARRL 10-meter contest was a nice surprise,
considering that we're close to the bottom of this solar cycle.
Here in the Pacific Northwest from morning to mid-day seemed quite
good, with lots of transequatorial propagation to South America,
with the Caribbean quite strong as well. In North America we were
mostly hearing southern states, from New Mexico, Texas, across the
Gulf Coast, and on up into North Carolina, Tennessee and Virginia.

Average daily sunspot numbers were down over 18 points for the week
(when compared to the previous seven days), and average solar flux
values were down nearly six points. Geomagnetic indices indicate
quiet for the most part, although the days of the contest were

Don't expect any big changes over the next week. Solar activity
should stay about the same. RWC Prague expects December 18 and 19 to
be quiet (geomagnetically), quiet to unsettled conditions on
December 17, 20 and 21, and unsettled December 16 and 22.

Jon Shea, N3DRK of Liberty, North Carolina asked about the ACE-HF
PRO System Simulation and Visualization Software (see We mentioned this program back in the June
28, 2002 Propagation Forecast Bulletin ARLP026 (you can read it on
the web at, but
haven't tried it since. Do any readers use this software for
predicting HF propagation?

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 and an explanation
of the numbers used in this bulletin see the ARRL Technical
Information Service propagation page at, An archive of past
bulletins is found at,

Sunspot numbers for December 8 through 14 were 51, 61, 55, 51, 41,
67 and 55 with a mean of 54.4. 10.7 cm flux was 89.6, 89.1, 91.4,
93.1, 88.3, 87.9, and 89.6, with a mean of 89.9. Estimated planetary
A indices were 1, 4, 12, 22, 9, 5 and 2 with a mean of 7.9.
Estimated mid-latitude A indices were 1, 3, 17, 10, 7, 4 and 2, with
a mean of 6.3.


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