ZCZC AP41
QST de W1AW
Propagation Forecast Bulletin 41 ARLP041
From Tad Cook, K7VVV
Seattle, WA October 10, 1997
To all radio amateurs
SB PROP ARL ARLP041
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 5.9.