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ARRL Propagation Bulletin ARLP041 (1997)

ARLP041 Propagation de K7VVV

Propagation Forecast Bulletin 41  ARLP041
From Tad Cook, K7VVV
Seattle, WA  October 10, 1997
To all radio amateurs

ARLP041 Propagation de K7VVV

Solar flux was down this week, an average of four points below the
previous week.  Sunspot numbers were also down, an average of almost
8 points.  Average solar flux for the previous ninety days rose
another point on October 6 to 84, on the same day the solar flux
finally dipped below the 90 day average when it hit 83.7.  The solar
flux was above the average for the previous ninety days for 62
consecutive days, which is a good trend.  Cycle 23 is definitely on
the rise.

Solar flux is expected to rise again immediately, above 85 by
October 12, above 90 a week later, and up around the low to
mid-nineties around October 23.  It may be back to the mid-eighties
around the end of the month.  Look for disturbed geomagnetic
conditions with possible high absorption of high latitude signals
around October 12, 18, 25, and 28.

When the solar flux is high and A and K indices are low, look for
good 10, 12, 15 and 17 meter conditions, especially on north-south
paths.  20 meters is still the best band during daylight and early
evening hours.  30, 40 and 80 meters will get better as we move
toward winter and nighttime static levels subside.

Sunspot Numbers for October 2 through 8 were 26, 27, 26, 26, 24, 35
and 17 with a mean of 25.9.  10.7 cm flux was 85.9, 85.7, 83.4,
84.4, 83.7, 83.5 and 82.9, with a mean of 84.2, and estimated
planetary A indices were 4, 7, 4, 2, 3, 7, and 14, with a mean of