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ARRL Propagation Bulletin ARLP015 (2004)

ARLP015 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 15  ARLP015
From Tad Cook, K7RA
Seattle, WA  April 8, 2004
To all radio amateurs 

ARLP015 Propagation de K7RA

This bulletin is going out a day early because ARRL Headquarters
will be closed for the Good Friday holiday.

Both solar flux values and sunspot numbers dropped this week.
Average daily sunspot numbers declined over 46 points and solar flux
was down nearly 20.

Solar flux is expected to rise over the next couple of days.
Predicted solar flux for Thursday through Monday, April 8-12, is 105
for Thursday and Friday, and 100 for Saturday through Monday. Flux
values and sunspots should rise again for a few days next week.

A coronal mass ejection near sunspot 588 spewed toward earth on
April 6. Currently that sunspot is squarely in the center of the
solar disk, aimed straight at us. The ejection should hit earth
today (April 8). The predicted planetary A index for Thursday
through Monday, April 8-12, is 30, 20, 15, 12 and 8.

There was a solar wind a couple of days back that caused geomagnetic
instability late on April 5th and through most of April 6th.
Another solar wind on April 3rd caused similar conditions.

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 April 1 through 7 were 100, 99, 68, 69, 85, 66
and 57 with a mean of 77.7. 10.7 cm flux was 112.8, 108.1, 107.4,
108.9, 108.7, 101.4 and 98.1, with a mean of 106.5. Estimated
planetary A indices were 3, 3, 23, 12, 14, 21 and 10, with a mean of


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