ARRL

ARRL Propagation Bulletin ARLP018 (1998)

SB PROP @ ARL $ARLP018
ARLP018 Propagation de K7VVV

ZCZC AP18
QST de W1AW
Propagation Forecast Bulletin 18  ARLP018
From Tad Cook, K7VVV
Seattle, WA  May 1, 1998
To all radio amateurs

SB PROP ARL ARLP018
ARLP018 Propagation de K7VVV

Thanks to KH6BZF for writing last week's bulletin while I was in
Maui.  Those who keep careful track of the numbers at the end of
these bulletins or who use them in the WA4TTK Solar Data Display
program may have noticed that there was a one day gap in last week's
numbers.  Note that the complete stats for the past two weeks are at
the end of this bulletin.

A trip to another region is always interesting when one can observe
propagation.  For this author, it was Bahia, Brazil in late 1995 and
Maui, Hawaii at KH6X last week.

The station and location were ideal, with no local noise sources and
big antennas high above the Pacific.  Being from the Pacific
Northwest, the first thing I noticed was that ten meters was often
open to the southern part of the United States, but never to
northern latitudes, at least with the sunspot activity as it was.

Solar flux has been declining over the past few weeks, and now it is
back on the rise.  The predicted flux values for this Friday,
Saturday and Sunday are 104, 106 and 108.  Beyond that, flux values
are expected to peak near 130 around May 8 and 9, then decline below
110 around May 15 and below 100 by May 17.  Geomagnetic conditions
have been active due to solar flares and coronal holes.  The worst
days recently were April 24 to 26, and we should see poor conditions
again this Saturday, due to a flare on April 29 at 1637z.  Active
conditions should return around May 21 to 23 with an active coronal
hole.

For the next few weeks, look for best worldwide propagation on 20
meters, with openings following local sunrise and continuing through
the day.  After dark, 20 should be excellent into the tropical
regions well into the night.  Because of shorter dark hours, 40
should offer fewer openings.  When solar flux is up, look for
openings on 10 and 15 meters, particularly when WWV reports K
indices of 2 or lower.

Sunspot Numbers for April 16 through 22 were 59, 70, 28, 35, 35, 47
and 41 with a mean of 45.  10.7 cm flux was 106.4, 101.3, 98.5,
96.2, 97.7, 92 and 87.6, with a mean of 97.1, and estimated
planetary A indices were 7, 15, 6, 4, 10, 7, and 6, with a mean of
7.9.

Sunspot Numbers for April 23 through 29 were 38, 22, 50, 30, 19, 54
and 65 with a mean of 39.7.  10.7 cm flux was 90.2, 90.6, 91.9,
90.7, 91.4, 98.4 and 100.5, with a mean of 93.4, and estimated
planetary A indices were 14, 35, 22, 31, 14, 10, and 6, with a mean
of 18.9.
NNNN
/EX