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ARRL Propagation Bulletin ARLP010 (2004)

ARLP010 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 10  ARLP010
From Tad Cook, K7RA
Seattle, WA  March 5, 2004
To all radio amateurs 

ARLP010 Propagation de K7RA

The ARRL International DX Phone Contest is this weekend, March 6-7,
and propagation should be good. Geomagnetic conditions are expected
to be quiet, with the predicted planetary A index at 10 for Friday,
March 5, and just 8 for the following three days. Solar flux is
expected to rise to 105 for Friday and 110 for the following three
days. Solar flux is currently expected to stay above 100 until March

Average daily sunspot numbers for the past week were up nearly 15
points to 76.9, compared to the earlier week, and average daily
solar flux increased over 5 points. Geomagnetic indices were about
double this week over last. A solar wind stream caused this, but no
geomagnetic storm erupted. Around March 10 and 11, earth should
enter another solar wind, and this could cause a geomagnetic storm,
possibly lasting until March 12.

The vernal equinox is only two weeks away. It will occur on
Saturday, March 20, and will be the beginning of spring. For the
next few weeks HF radio conditions should seasonally improve.

For more information concerning propagation and an explanation of
the numbers used in this bulletin see the Propagation page on the
ARRL Web site at

Sunspot numbers for February 26 through March 3 were 105, 90, 104,
81, 66, 50 and 42 with a mean of 76.9. 10.7 cm flux was 120.8,
122.2, 115.8, 110, 101.8, 98.8 and 90.4, with a mean of 108.5.
Estimated planetary A indices were 5, 11, 20, 21, 18, 17 and 15,
with a mean of 15.3.


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