QST de W1AW
Propagation Forecast Bulletin 17 ARLP017
From Tad Cook, KT7H
Seattle, WA April 26, 1996
To all radio amateurs
SB PROP ARL ARLP017
ARLP017 Propagation de KT7H
Solar activity was up a little last week, but geomagnetic activity remained high also. The average Boulder A index was 15.9, the previous week was 15.4, and it was 5.7 the week before that. The A index is a daily indication of geomagnetic field stability, and values below ten generally mean that the field is stable and absorption is low.
Average sunspot numbers were up by over 12 points this week.
We are at or near the solar activity minimum. 30 meters is probably the best daytime band for long distance communications, with 20 meters a fair bet when solar flux rises slightly. Solar flux is expected to remain at or below 70 until after the first week of May. It should peak around the mid-seventies around May 11, and then fall below 70 again after May 18. The geomagnetic field should stay stable between April 29 and May 8, and then expected disturbances center around May 11, 14 and 15.
Sunspot Numbers for April 18 through 24 were 29, 26, 28, 18, 15, 12 and 11, with a mean of 19.9. 10.7 cm flux was 70.1, 70.5, 71.5, 74, 72.4, 71.1 and 68.6, with a mean of 71.2.