Register Account

Login Help

ARRL Propagation Bulletin ARLP050 (2004)

ARLP050 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 50  ARLP050
From Tad Cook, K7RA
Seattle, WA  December 3, 2004
To all radio amateurs 

ARLP050 Propagation de K7RA

Sunspot numbers and geomagnetic activity were both up slightly over
the past week. Average daily sunspot numbers were low, rising from
50 to 55.1 since the week before. Average daily solar flux rose from
103.8 to 110.9 over the same period.

During November the average daily sunspot numbers were 70.5. This is
slightly lower than the 77.9 average for October.

Geomagnetic indices were unsettled over the past week, with daily A
indices for both mid-latitude and high latitude in the mid to high

Over the next few days the solar flux should decline. The predicted
daily solar flux for Friday December 3 through Monday December 6 is
predicted to be 105, 100, 100 and 95. Solar flux should reach a near
term low around December 8-9 at 90. Geomagnetic conditions should
remain quiet until December 6, when the predicted planetary A index
is 20. This may be far enough off to have good quiet conditions for
the ARRL 160-Meter CW Contest this weekend.

Gary Johnson, K5SWW wrote to mention an interesting propagation
condition he monitored this weekend toward the end of the CQ World
Wide CW DX Contest. From 2100-2200z, 10 meter CW signals from
Scandinavia were heard quite strong at his home in Paradise, Texas,
which is northwest of Dallas/Fort Worth, Texas. Some were quite
strong and a little raspy. He notes that it was dark in Scandinavia,
and he was surprised to hear their signals on a daylight band. Did
anyone else experience this?

If you would like to comment or have a tip, email the author at,

For more information concerning propagation and an explanation of
the numbers used in this bulletin see the ARRL Technical Information
Service propagation page at, .

Sunspot numbers for November 25 through December 1 were 61, 61, 64,
66, 40, 42 and 52 with a mean of 55.1. 10.7 cm flux was 109.4,
111.1, 110.3, 112.8, 111.4, 110.6 and 111, with a mean of 110.9.
Estimated planetary A indices were 20, 13, 10, 14, 15, 15 and 13
with a mean of 14.3. Estimated mid-latitude A indices were 19, 16,
10, 16, 20, 16 and 11, with a mean of 15.4.


Instragram     Facebook     Twitter     YouTube     LinkedIn