ZCZC AP16
QST de W1AW
Propagation Forecast Bulletin 16 ARLP016
From Tad Cook, KT7H
Seattle, WA April 18, 1997
To all radio amateurs
SB PROP ARL ARLP016
ARLP016 Propagation de KT7H
Average solar flux was down a little with sunspot numbers up a bit over the past week. The most significant event was the delayed reaction to the big solar mass ejection, which drove the Planetary A index to 38 and K index up to 7 on April 11.
Over the next few days watch for a retreat in the solar flux from the high seventies down to the low seventies until the end of the first week in May, when it will start creeping up to the eighties again. Solar flux is expected to be above 80 by May 10. Look for geomagnetic disturbances to appear again around April 24 and 25. All of this forecast is based upon activity seen during the last solar rotation, and of course new activity could appear at any time.
Sunspot Numbers for April 10 through 16 were 47, 31, 30, 34, 45, 39 and 33 with a mean of 37. 10.7 cm flux was 77.6, 77.1, 76.4, 78.8, 77.4, 78.7 and 75, with a mean of 77.3, and estimated planetary A indices were 10, 38, 9, 8, 4, 4, and 12, with a mean of 12.1.