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ARRL Propagation Bulletin ARLP030 (2009)

ARLP030 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 30  ARLP030
From Tad Cook, K7RA
Seattle, WA  July 24, 2009
To all radio amateurs 

ARLP030 Propagation de K7RA

No new sunspots yet, but a big surprise this week with aurora and a
geomagnetic storm.  The activity peaked around 0300-0900z on
Wednesday July 22, with K index as high as 6.  Planetary A index for
the day was 24.  You can see the K index variation at  One nice result
was aurora propagation on six meters.

A week ago there wasn't any indicator of increased activity.  If you
go to and click
on July 21, you can see that the forecast was modified more than
once, but the highest forecast was an A index of only 15.

KN5O and N5OMG in Louisiana both worked JA7QVI on six meters on June
17.  KN5O worked him at 2359z, and 30 minutes later reported that
the JA7QVI signal was still holding steady at S2.  This was on a
Friday, five days before the aurora.

Patrick Hamel, W5THT in Mississippi on July 17 noted that July
propagation on six meters is some of the best he has ever
experienced.  He wonders if the volcano erupting on Sarychev Peak on
Matua Island is spewing conductive ash, possibly reflecting radio
waves.  I don't know if that is true or not, but at you can see
dramatic photos of the eruption.

There is a new sunspot trying to emerge today, but it looks to be
from old cycle 23.

Geophysical Institute Prague predicts quiet geomagnetic conditions
July 24-25, quiet to unsettled July 26, and back to quiet for July

The U.S. Air Force and NOAA Space Weather Prediction Center calls
for planetary A index of 5 for July 24-25, 8 on July 26, 7 on July
27, and back to 5 though the end of the month.  They predict solar
flux on July 24-26 at 68, 69 and 70, remaining at 70 through August

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 at  For a detailed
explanation of the numbers used in this bulletin, see  An archive of past
propagation bulletins is at

Monthly propagation charts between four USA regions and twelve
overseas locations are at

Instructions for starting or ending email distribution of this
bulletin are at

Sunspot numbers for July 16 through 22 were 0, 0, 0, 0, 0, 0, and 0
with a mean of 0.  10.7 cm flux was 66.7, 66.2, 67, 67.6, 68.2,
67.7, and 67.8 with a mean of 67.3.  Estimated planetary A indices
were 4, 2, 3, 2, 6, 4 and 24 with a mean of 6.4.  Estimated
mid-latitude A indices were 2, 0, 1, 1, 3, 3 and 18 with a mean of


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